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Posted to commits@tapestry.apache.org by bo...@apache.org on 2017/09/16 01:54:20 UTC
svn commit: r1018226 [17/41] - in /websites/production/tapestry/content: ./
cache/ styles/
Modified: websites/production/tapestry/content/forms-and-validation.html
==============================================================================
--- websites/production/tapestry/content/forms-and-validation.html (original)
+++ websites/production/tapestry/content/forms-and-validation.html Sat Sep 16 01:54:19 2017
@@ -27,6 +27,16 @@
</title>
<link type="text/css" rel="stylesheet" href="/resources/space.css" />
+ <link href='/resources/highlighter/styles/shCoreCXF.css' rel='stylesheet' type='text/css' />
+ <link href='/resources/highlighter/styles/shThemeCXF.css' rel='stylesheet' type='text/css' />
+ <script src='/resources/highlighter/scripts/shCore.js' type='text/javascript'></script>
+ <script src='/resources/highlighter/scripts/shBrushJava.js' type='text/javascript'></script>
+ <script src='/resources/highlighter/scripts/shBrushXml.js' type='text/javascript'></script>
+ <script src='/resources/highlighter/scripts/shBrushPlain.js' type='text/javascript'></script>
+ <script>
+ SyntaxHighlighter.defaults['toolbar'] = false;
+ SyntaxHighlighter.all();
+ </script>
<link href="/styles/style.css" rel="stylesheet" type="text/css"/>
@@ -67,14 +77,68 @@
</div>
<div id="content">
- <div id="ConfluenceContent"><p><strong>Forms</strong> are the traditional way for most web applications to gather significant information from the user. Whether it's a search form, a login screen or a multi-page registration wizard, Tapestry uses standard HTML forms, with HTTP POST actions by default. In addition, AJAX-based form submission is supported using <a href="ajax-and-zones.html">Zones</a>.</p><parameter ac:name="style">float:right</parameter><parameter ac:name="title">Related Articles</parameter><parameter ac:name="class">aui-label</parameter><rich-text-body><parameter ac:name="showLabels">false</parameter><parameter ac:name="showSpace">false</parameter><parameter ac:name="title">Related Articles</parameter><parameter ac:name="cql">label in ("validation","forms") and space = currentSpace()</parameter></rich-text-body><p> </p><p>Tapestry provides support for creating and rendering forms, populating their fields, and validating user input. For simple ca
ses, input validation is declarative, meaning you simply tell Tapestry what validations to apply to a given field, and it takes care of it on the server and (optionally) on the client as well. In addition, you can provide event handler methods in your page or component classes to handle more complex validation scenarios.</p><p>Finally, Tapestry not only makes it easy to present errors messages to the user, but it can also automatically highlight form fields when validation fails.</p><p><strong>Contents</strong></p><p></p><h2 id="FormsandValidation-TheFormComponent">The Form Component</h2><p>The core of Tapestry's form support is the <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/Form.html">Form</a> component. The Form component encloses (wraps around) all the other <em>field components</em> such as <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components
/TextField.html">TextField</a>, <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/TextArea.html">TextArea</a>, <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/Checkbox.html">Checkbox</a>, etc.</p><h2 id="FormsandValidation-FormEvents">Form Events</h2><p>The Form component emits a number of <a href="component-events.html">component events</a>. You'll want to provide event handler methods for some of these.</p><p>When rendering, the Form component emits two events: first, "prepareForRender", then "prepare". These allow the Form's container to set up any fields or properties that will be referenced in the form. For example, this is a good place to create a temporary entity object to be rendered, or to load an entity from a database to be edited.</p><p>When user submits the form on the client, a series of steps occur on the server.</p><p>First, the Form em
its a "prepareForSubmit" event, then a "prepare" event. These allow the container to ensure that objects are set up and ready to receive information from the form submission.</p><p>Next, all the fields inside the form are <em>activated</em> to pull values out of the incoming request, validate them and (if valid) store the changes.<plain-text-body>{float:right|width=25%|background=#eee}
-_For Tapestry 4 Users:_ Tapestry 5 does not use the fragile "form rewind" approach from Tapestry 4. Instead, a hidden field generated during the render stores the information needed to process the form submission.
-{float}</plain-text-body> </p><p>After the fields have done their processing, the Form emits a "validate" event. This is your chance to perform any cross-form validation that can't be described declaratively.</p><p>Next, the Form determines if there have been any validation errors. If there have been, then the submission is considered a failure, and a "failure" event is emitted. If there have been no validation errors, then a "success" event is emitted.</p><p>Finally, the Form emits a "submit" event, for logic that doesn't care about success or failure.</p><div class="table-wrap"><table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1" class="confluenceTh"><p>Form Event (in order)</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>Phase</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>When emitted (and typical use)</p></th><th colspan="1" rowspan="1" class="confluenceTh">Method Name</th><th colspan="1" rowspan="1" class="confluenceTh">@OnEvent C
onstant</th></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>prepareForRender</strong></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Render</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Before rendering the form (e.g. load an entity from a database to be edited)</p></td><td colspan="1" rowspan="1" class="confluenceTd">onPrepareForRender()</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.PREPARE_FOR_RENDER</td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>prepare</strong></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Render</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Before rendering the form, but after <em>prepareForRender</em></p></td><td colspan="1" rowspan="1" class="confluenceTd">onPrepare()</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.PREPARE</td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>prepareForSubmit</stron
g></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Submit</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Before the submitted form is processed</p></td><td colspan="1" rowspan="1" class="confluenceTd">onPrepareForSubmit()</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.PREPARE_FOR_SUBMIT</td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>prepare</strong></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Submit</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Before the submitted form is processed, but after <em>prepareForSubmit</em></p></td><td colspan="1" rowspan="1" class="confluenceTd">onPrepare()</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.PREPARE</td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>validate</strong></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Submit</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>After f
ields have been populated from submitted values and validated (e.g. perform cross-field validation)</p></td><td colspan="1" rowspan="1" class="confluenceTd">onValidate</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.VALIDATE</td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>validateForm</strong></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Submit</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>same as <em>validate (deprecated – do not use)<br clear="none"></em></p></td><td colspan="1" rowspan="1" class="confluenceTd"><em>onValidateForm</em></td><td colspan="1" rowspan="1" class="confluenceTd"> </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>failure</strong></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Submit</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>After one or more validation errors have occurred</p></td><td colspan="1" rowspan="1" class="conf
luenceTd">onFailure()</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.FAILURE</td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>success</strong></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Submit</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>When validation has completed <em>without</em> any errors (e.g. save changes to the database)</p></td><td colspan="1" rowspan="1" class="confluenceTd">onSuccess()</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.SUCCESS</td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>submit</strong></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Submit</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>After all validation (success or failure) has finished</p></td><td colspan="1" rowspan="1" class="confluenceTd">onSubmit()</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.SUBMIT</td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><strong>canceled</strong></td><td colspan="1" rowspan="1" class="confluenceTd">Submit</td><td colspan="1" rowspan="1" class="confluenceTd">Whenever a <em>Submit</em> or <em>LinkSubmit</em> component containing <em>mode="cancel"</em> or <em>mode="unconditional"</em> is clicked</td><td colspan="1" rowspan="1" class="confluenceTd">onCanceled()</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.CANCELED</td></tr></tbody></table></div><p>Note that the "prepare" event is emitted during both form rendering and form submission.</p><h2 id="FormsandValidation-HandlingEvents">Handling Events</h2><p>Main Article: <a href="component-events.html">Component Events</a></p><p>You handle events by providing methods in your page or component class, either following the on<strong><em>Event</em></strong>From<strong><em>Component</em></strong>() naming convention or using the OnEvent annotation. For example:</p><parameter ac:name="language">java</paramet
er><parameter ac:name="title">Event Handler Using Naming Convention</parameter><plain-text-body> void onValidateFromPassword() { ...}</plain-text-body><p>or the equivalent using @OnEvent:</p><parameter ac:name="language">java</parameter><parameter ac:name="title">Event Handler Using @OnEvent Annotation</parameter><plain-text-body> @OnEvent(value=EventConstants.VALIDATE, component="password")
- void verifyThePassword() { ...}</plain-text-body><h2 id="FormsandValidation-TrackingValidationErrors">Tracking Validation Errors</h2><p>Associated with the Form is a <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/ValidationTracker.html">ValidationTracker</a> that tracks all the provided user input and validation errors for every field in the form. The tracker can be provided to the Form via the Form's tracker parameter, but this is rarely necessary.</p><p>The Form includes methods <code>isValid()</code> and <code>getHasErrors()</code>, which are used to see if the Form's validation tracker contains any errors.</p><p>In your own logic, it is possible to record your own errors. Form includes two different versions of method <code>recordError()</code>, one of which specifies a <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/Field.html">Field</a> (an interface implemented by all form ele
ment components), and one of which is for "global" errors, not associated with any particular field. If the error concerns only a single field, you should use the first version so that the field will be highlighted.</p><h2 id="FormsandValidation-StoringDataBetweenRequests">Storing Data Between Requests</h2><p><plain-text-body>{float:right|width=40%}
-{info:title=New in Tapestry 5.4}
-Starting in Tapestry 5.4, the default behavior for server-side validation failures is to re-render the page within the same request (rather than emitting a redirect). This removes the need to use a session-persistent field to store the validation tracker when validation failures occur.
-{info}
-{float}</plain-text-body>As with other action requests, the result of a form submission (except when using <a href="ajax-and-zones.html">Zones</a>) is to send a redirect to the client, which results in a second request (to re-render the page). The ValidationTracker must be <a href="persistent-page-data.html">persisted</a> (generally in the HttpSession) across these two requests in order to prevent the loss of validation information. Fortunately, the default ValidationTracker provided by the Form component is persistent, so you don't normally have to worry about it.</p><p>However, for the same reason, the individual fields updated by the components should also be persisted across requests, and this is something you <strong>do</strong> need to do yourself – generally with the @Persist annotation.</p><p>For example, a Login page class, which collects a user name and a password, might look like:</p><parameter ac:name="language">java</parameter><parameter ac:name="title">Login.ja
va Example</parameter><plain-text-body>package com.example.newapp.pages;
+ <div id="ConfluenceContent"><p><strong>Forms</strong> are the traditional way for most web applications to gather significant information from the user. Whether it's a search form, a login screen or a multi-page registration wizard, Tapestry uses standard HTML forms, with HTTP POST actions by default. In addition, AJAX-based form submission is supported using <a href="ajax-and-zones.html">Zones</a>.</p><div class="aui-label" style="float:right" title="Related Articles">
+
+
+
+
+
+
+
+
+<h3>Related Articles</h3>
+
+<ul class="content-by-label"><li>
+ <div>
+ <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span> </div>
+
+ <div class="details">
+ <a href="forms-and-validation.html">Forms and Validation</a>
+
+
+ </div>
+ </li><li>
+ <div>
+ <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span> </div>
+
+ <div class="details">
+ <a href="forms-and-form-components-faq.html">Forms and Form Components FAQ</a>
+
+
+ </div>
+ </li><li>
+ <div>
+ <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span> </div>
+
+ <div class="details">
+ <a href="bean-validation.html">Bean Validation</a>
+
+
+ </div>
+ </li></ul>
+</div>
+
+
+<p> </p><p>Tapestry provides support for creating and rendering forms, populating their fields, and validating user input. For simple cases, input validation is declarative, meaning you simply tell Tapestry what validations to apply to a given field, and it takes care of it on the server and (optionally) on the client as well. In addition, you can provide event handler methods in your page or component classes to handle more complex validation scenarios.</p><p>Finally, Tapestry not only makes it easy to present errors messages to the user, but it can also automatically highlight form fields when validation fails.</p><p><strong>Contents</strong></p><p><style type="text/css">/*<![CDATA[*/
+div.rbtoc1499639542745 {padding: 0px;}
+div.rbtoc1499639542745 ul {list-style: disc;margin-left: 0px;}
+div.rbtoc1499639542745 li {margin-left: 0px;padding-left: 0px;}
+
+/*]]>*/</style></p><div class="toc-macro rbtoc1499639542745">
+<ul class="toc-indentation"><li>Related Articles</li></ul>
+<ul><li><a href="#FormsandValidation-TheFormComponent">The Form Component</a></li><li><a href="#FormsandValidation-FormEvents">Form Events</a></li><li><a href="#FormsandValidation-HandlingEvents">Handling Events</a></li><li><a href="#FormsandValidation-TrackingValidationErrors">Tracking Validation Errors</a></li><li><a href="#FormsandValidation-StoringDataBetweenRequests">Storing Data Between Requests</a></li><li><a href="#FormsandValidation-ConfiguringFieldsandLabels">Configuring Fields and Labels</a></li><li><a href="#FormsandValidation-CentralizingValidationwith@Validate">Centralizing Validation with @Validate</a></li><li><a href="#FormsandValidation-ServerSideValidation">Server Side Validation</a></li><li><a href="#FormsandValidation-CustomizingValidationMessages">Customizing Validation Messages</a>
+<ul class="toc-indentation"><li><a href="#FormsandValidation-CustomizingValidationMessagesforBeanEditForm">Customizing Validation Messages for BeanEditForm</a></li></ul>
+</li><li><a href="#FormsandValidation-ConfiguringValidatorContraintsintheMessageCatalog">Configuring Validator Contraints in the Message Catalog</a></li><li><a href="#FormsandValidation-ValidationMacros">Validation Macros</a></li><li><a href="#FormsandValidation-OverridingtheTranslatorwithEvents">Overriding the Translator with Events</a></li></ul>
+</div><h2 id="FormsandValidation-TheFormComponent">The Form Component</h2><p>The core of Tapestry's form support is the <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/Form.html">Form</a> component. The Form component encloses (wraps around) all the other <em>field components</em> such as <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/TextField.html">TextField</a>, <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/TextArea.html">TextArea</a>, <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/Checkbox.html">Checkbox</a>, etc.</p><h2 id="FormsandValidation-FormEvents">Form Events</h2><p>The Form component emits a number of <a href="component-events.html">component events</a>. You'll want to provide event handler methods for
some of these.</p><p>When rendering, the Form component emits two events: first, "prepareForRender", then "prepare". These allow the Form's container to set up any fields or properties that will be referenced in the form. For example, this is a good place to create a temporary entity object to be rendered, or to load an entity from a database to be edited.</p><p>When user submits the form on the client, a series of steps occur on the server.</p><p>First, the Form emits a "prepareForSubmit" event, then a "prepare" event. These allow the container to ensure that objects are set up and ready to receive information from the form submission.</p><p>Next, all the fields inside the form are <em>activated</em> to pull values out of the incoming request, validate them and (if valid) store the changes.</p><div class="navmenu" style="float:right; width:25%; background:#eee; margin:3px; padding:3px">
+<p><em>For Tapestry 4 Users:</em> Tapestry 5 does not use the fragile "form rewind" approach from Tapestry 4. Instead, a hidden field generated during the render stores the information needed to process the form submission.</p></div> <p>After the fields have done their processing, the Form emits a "validate" event. This is your chance to perform any cross-form validation that can't be described declaratively.</p><p>Next, the Form determines if there have been any validation errors. If there have been, then the submission is considered a failure, and a "failure" event is emitted. If there have been no validation errors, then a "success" event is emitted.</p><p>Finally, the Form emits a "submit" event, for logic that doesn't care about success or failure.</p><div class="table-wrap"><table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1" class="confluenceTh"><p>Form Event (in order)</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>Phase</p></th><th colspan
="1" rowspan="1" class="confluenceTh"><p>When emitted (and typical use)</p></th><th colspan="1" rowspan="1" class="confluenceTh">Method Name</th><th colspan="1" rowspan="1" class="confluenceTh">@OnEvent Constant</th></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>prepareForRender</strong></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Render</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Before rendering the form (e.g. load an entity from a database to be edited)</p></td><td colspan="1" rowspan="1" class="confluenceTd">onPrepareForRender()</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.PREPARE_FOR_RENDER</td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>prepare</strong></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Render</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Before rendering the form, but after <em>prepareForRender</em></p></td><td colspan="1" rowspan="1" c
lass="confluenceTd">onPrepare()</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.PREPARE</td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>prepareForSubmit</strong></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Submit</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Before the submitted form is processed</p></td><td colspan="1" rowspan="1" class="confluenceTd">onPrepareForSubmit()</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.PREPARE_FOR_SUBMIT</td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>prepare</strong></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Submit</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Before the submitted form is processed, but after <em>prepareForSubmit</em></p></td><td colspan="1" rowspan="1" class="confluenceTd">onPrepare()</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.PREPARE</td></tr><tr><td cols
pan="1" rowspan="1" class="confluenceTd"><p><strong>validate</strong></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Submit</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>After fields have been populated from submitted values and validated (e.g. perform cross-field validation)</p></td><td colspan="1" rowspan="1" class="confluenceTd">onValidate</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.VALIDATE</td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>validateForm</strong></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Submit</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>same as <em>validate (deprecated – do not use)<br clear="none"></em></p></td><td colspan="1" rowspan="1" class="confluenceTd"><em>onValidateForm</em></td><td colspan="1" rowspan="1" class="confluenceTd"> </td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>failure</strong></p></td><td colspan=
"1" rowspan="1" class="confluenceTd"><p>Submit</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>After one or more validation errors have occurred</p></td><td colspan="1" rowspan="1" class="confluenceTd">onFailure()</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.FAILURE</td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>success</strong></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Submit</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>When validation has completed <em>without</em> any errors (e.g. save changes to the database)</p></td><td colspan="1" rowspan="1" class="confluenceTd">onSuccess()</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.SUCCESS</td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>submit</strong></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Submit</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>After all validation (s
uccess or failure) has finished</p></td><td colspan="1" rowspan="1" class="confluenceTd">onSubmit()</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.SUBMIT</td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><strong>canceled</strong></td><td colspan="1" rowspan="1" class="confluenceTd">Submit</td><td colspan="1" rowspan="1" class="confluenceTd">Whenever a <em>Submit</em> or <em>LinkSubmit</em> component containing <em>mode="cancel"</em> or <em>mode="unconditional"</em> is clicked</td><td colspan="1" rowspan="1" class="confluenceTd">onCanceled()</td><td colspan="1" rowspan="1" class="confluenceTd">EventConstants.CANCELED</td></tr></tbody></table></div><p>Note that the "prepare" event is emitted during both form rendering and form submission.</p><h2 id="FormsandValidation-HandlingEvents">Handling Events</h2><p>Main Article: <a href="component-events.html">Component Events</a></p><p>You handle events by providing methods in your page or component class, ei
ther following the on<strong><em>Event</em></strong>From<strong><em>Component</em></strong>() naming convention or using the OnEvent annotation. For example:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeHeader panelHeader pdl" style="border-bottom-width: 1px;"><b>Event Handler Using Naming Convention</b></div><div class="codeContent panelContent pdl">
+<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> void onValidateFromPassword() { ...}</pre>
+</div></div><p>or the equivalent using @OnEvent:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeHeader panelHeader pdl" style="border-bottom-width: 1px;"><b>Event Handler Using @OnEvent Annotation</b></div><div class="codeContent panelContent pdl">
+<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> @OnEvent(value=EventConstants.VALIDATE, component="password")
+ void verifyThePassword() { ...}</pre>
+</div></div><h2 id="FormsandValidation-TrackingValidationErrors">Tracking Validation Errors</h2><p>Associated with the Form is a <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/ValidationTracker.html">ValidationTracker</a> that tracks all the provided user input and validation errors for every field in the form. The tracker can be provided to the Form via the Form's tracker parameter, but this is rarely necessary.</p><p>The Form includes methods <code>isValid()</code> and <code>getHasErrors()</code>, which are used to see if the Form's validation tracker contains any errors.</p><p>In your own logic, it is possible to record your own errors. Form includes two different versions of method <code>recordError()</code>, one of which specifies a <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/Field.html">Field</a> (an interface implemented by all form element components), and one of which is for
"global" errors, not associated with any particular field. If the error concerns only a single field, you should use the first version so that the field will be highlighted.</p><h2 id="FormsandValidation-StoringDataBetweenRequests">Storing Data Between Requests</h2><p></p><div class="navmenu" style="float:right; width:40%; background:white; margin:3px; padding:3px">
+<div class="confluence-information-macro confluence-information-macro-information"><p class="title">New in Tapestry 5.4</p><span class="aui-icon aui-icon-small aui-iconfont-info confluence-information-macro-icon"></span><div class="confluence-information-macro-body">
+<p>Starting in Tapestry 5.4, the default behavior for server-side validation failures is to re-render the page within the same request (rather than emitting a redirect). This removes the need to use a session-persistent field to store the validation tracker when validation failures occur.</p></div></div></div>As with other action requests, the result of a form submission (except when using <a href="ajax-and-zones.html">Zones</a>) is to send a redirect to the client, which results in a second request (to re-render the page). The ValidationTracker must be <a href="persistent-page-data.html">persisted</a> (generally in the HttpSession) across these two requests in order to prevent the loss of validation information. Fortunately, the default ValidationTracker provided by the Form component is persistent, so you don't normally have to worry about it.<p>However, for the same reason, the individual fields updated by the components should also be persisted across requests, and this is som
ething you <strong>do</strong> need to do yourself – generally with the @Persist annotation.</p><p>For example, a Login page class, which collects a user name and a password, might look like:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeHeader panelHeader pdl" style="border-bottom-width: 1px;"><b>Login.java Example</b></div><div class="codeContent panelContent pdl">
+<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">package com.example.newapp.pages;
import com.example.newapp.services.UserAuthenticator;
@@ -120,11 +184,11 @@ public class Login {
}
-</plain-text-body><p><plain-text-body>{float:right|width=40%}
-{info}
-Note that the onValidateFromLoginForm() and onSuccess() methods are not public; event handler methods can have any visibility, even private. Package private (that is, no modifier) is the typical use, as it allows the component to be tested, from a test case class in the same package.
-{info}
-{float}</plain-text-body>Because a form submission is really <em>two</em> requests: the submission itself (which results in a redirect response), then a second request for the page (which results in a re-rendering of the page), it is necessary to persist the userName field between the two requests, by using the @Persist annotation. This would be necessary for the password field as well, except that the <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/PasswordField.html">PasswordField</a> component never renders a value.</p><rich-text-body><p>To avoid data loss, fields whose values are stored in the HttpSession (such as userName, above) must be serializable, particularly if you want to be able to cluster your application or preserve sessions across server restarts.</p></rich-text-body><p>The Form only emits a "success" event if the there are no prior validation errors. This means it is not necessary to write <code>if (
form.getHasErrors()) return;</code> as the first line of the method.</p><p>Finally, notice how business logic fits into validation. The UserAuthenticator service is responsible for ensuring that the userName and (plaintext) password are valid. When it returns false, we ask the Form component to record an error. We provide the PasswordField instance as the first parameter; this ensures that the password field, and its label, are decorated when the Form is re-rendered, to present the errors to the user.</p><h2 id="FormsandValidation-ConfiguringFieldsandLabels">Configuring Fields and Labels</h2><p>The Login page template below contains a minimal amount of Tapestry instrumentation and references some of the <a class="external-link" href="http://getbootstrap.com" rel="nofollow">Bootstrap</a> CSS classes (Bootstrap is automatically integrated into each page by default, starting with Tapestry 5.4).</p><parameter ac:name="language">xml</parameter><parameter ac:name="title">Login.tml Exampl
e</parameter><plain-text-body><html t:type="layout" title="newapp com.example"
+</pre>
+</div></div><p></p><div class="navmenu" style="float:right; width:40%; background:white; margin:3px; padding:3px">
+<div class="confluence-information-macro confluence-information-macro-information"><span class="aui-icon aui-icon-small aui-iconfont-info confluence-information-macro-icon"></span><div class="confluence-information-macro-body">
+<p>Note that the onValidateFromLoginForm() and onSuccess() methods are not public; event handler methods can have any visibility, even private. Package private (that is, no modifier) is the typical use, as it allows the component to be tested, from a test case class in the same package.</p></div></div></div>Because a form submission is really <em>two</em> requests: the submission itself (which results in a redirect response), then a second request for the page (which results in a re-rendering of the page), it is necessary to persist the userName field between the two requests, by using the @Persist annotation. This would be necessary for the password field as well, except that the <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/PasswordField.html">PasswordField</a> component never renders a value.<div class="confluence-information-macro confluence-information-macro-tip"><span class="aui-icon aui-icon-small aui-iconfo
nt-approve confluence-information-macro-icon"></span><div class="confluence-information-macro-body"><p>To avoid data loss, fields whose values are stored in the HttpSession (such as userName, above) must be serializable, particularly if you want to be able to cluster your application or preserve sessions across server restarts.</p></div></div><p>The Form only emits a "success" event if the there are no prior validation errors. This means it is not necessary to write <code>if (form.getHasErrors()) return;</code> as the first line of the method.</p><p>Finally, notice how business logic fits into validation. The UserAuthenticator service is responsible for ensuring that the userName and (plaintext) password are valid. When it returns false, we ask the Form component to record an error. We provide the PasswordField instance as the first parameter; this ensures that the password field, and its label, are decorated when the Form is re-rendered, to present the errors to the user.</p><h2 id
="FormsandValidation-ConfiguringFieldsandLabels">Configuring Fields and Labels</h2><p>The Login page template below contains a minimal amount of Tapestry instrumentation and references some of the <a class="external-link" href="http://getbootstrap.com" rel="nofollow">Bootstrap</a> CSS classes (Bootstrap is automatically integrated into each page by default, starting with Tapestry 5.4).</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeHeader panelHeader pdl" style="border-bottom-width: 1px;"><b>Login.tml Example</b></div><div class="codeContent panelContent pdl">
+<pre class="brush: xml; gutter: false; theme: Default" style="font-size:12px;"><html t:type="layout" title="newapp com.example"
xmlns:t="http://tapestry.apache.org/schema/tapestry_5_4.xsd">
<div class="row">
@@ -139,18 +203,26 @@ Note that the onValidateFromLoginForm()
</div>
</html>
-</plain-text-body><p>Rendering the page gives a reasonably pleasing first pass:</p><p><span class="confluence-embedded-file-wrapper image-center-wrapper confluence-embedded-manual-size"><img class="confluence-embedded-image confluence-content-image-border image-center" width="500" src="forms-and-validation.data/newapp_com_example.png"></span></p><p>The Tapestry Form component is responsible for creating the necessary URL for the form submission (this is Tapestry's responsibility, not yours).</p><p><span style="line-height: 1.4285715;">For the TextField, we provide a component id, userName. We could specify the </span><code style="line-height: 1.4285715;">value</code><span style="line-height: 1.4285715;"> parameter, but the default is to match the TextField's id against a property of the container, the Login page, if such a property exists. </span></p><p>As a rule of thumb, you should always give your fields a specific id (this id will be used to generate the <code>name</code> a
nd <code>id</code> attributes of the rendered tag). Being allowed to omit the value parameter helps to keep the template from getting too cluttered.</p><p>The FormGroup mixin decorates the field with some additional markup, including a <label> element; this leverages more of Bootstrap.</p><parameter ac:name="language">xml</parameter><parameter ac:name="title">userName component as rendered</parameter><plain-text-body><div class="form-group">
+</pre>
+</div></div><p>Rendering the page gives a reasonably pleasing first pass:</p><p><span class="confluence-embedded-file-wrapper image-center-wrapper confluence-embedded-manual-size"><img class="confluence-embedded-image confluence-content-image-border image-center" width="500" src="forms-and-validation.data/newapp_com_example.png"></span></p><p>The Tapestry Form component is responsible for creating the necessary URL for the form submission (this is Tapestry's responsibility, not yours).</p><p><span style="line-height: 1.4285715;">For the TextField, we provide a component id, userName. We could specify the </span><code style="line-height: 1.4285715;">value</code><span style="line-height: 1.4285715;"> parameter, but the default is to match the TextField's id against a property of the container, the Login page, if such a property exists. </span></p><p>As a rule of thumb, you should always give your fields a specific id (this id will be used to generate the <code>name</code> and <co
de>id</code> attributes of the rendered tag). Being allowed to omit the value parameter helps to keep the template from getting too cluttered.</p><p>The FormGroup mixin decorates the field with some additional markup, including a <label> element; this leverages more of Bootstrap.</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeHeader panelHeader pdl" style="border-bottom-width: 1px;"><b>userName component as rendered</b></div><div class="codeContent panelContent pdl">
+<pre class="brush: xml; gutter: false; theme: Default" style="font-size:12px;"><div class="form-group">
<label for="userName" class="control-label">User Name</label>
<input id="userName" class="form-control" name="userName" type="text">
-</div></plain-text-body><p> </p><p><span style="color: rgb(83,145,38);font-size: 24.0px;line-height: 1.25;">Form Validation</span></p><p>The above example is a very basic form which allows the fields to be empty. However, with a little more effort we can add client-side validation to prevent the user from submitting the form with either field empty.</p><p>Validation in Tapestry involves associating one or more <em>validators</em> with a form element component, such as TextField or PasswordField. This is done using the <strong>validate</strong> parameter:</p><parameter ac:name="language">xml</parameter><plain-text-body><t:textfield t:id="userName" validate="required" t:mixins="formgroup"/>
-<t:passwordfield t:id="password" value="password" validate="required" t:mixins="formgroup"/></plain-text-body><p> </p><p><span style="color: rgb(83,145,38);font-size: 20.0px;line-height: 1.5;">Available Validators</span></p><p>Tapestry provides the following built-in validators:</p><div class="table-wrap"><table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1" class="confluenceTh"><p>Validator</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>Constraint Type</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>Description</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>Example</p></th></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>email</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>–</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Ensures that the given input looks like a valid e-mail address</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code><t:textfield value="emai
l" validate="email" /></code></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>max</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>long</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Enforces a maximum integer value</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code><t:textfield value="age" validate="max=120,min=0" /></code></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>maxLength</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>int</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Makes sure that a string value has a maximum length</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code><t:textfield value="zip" validate="maxlength=7" /></code></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>min</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>long</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Enforces a minimum
integer value</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code><t:textfield value="age" validate="max=120,min=0" /></code></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>minLength</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>int</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Makes sure that a string value has a minimum length</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code><t:textfield value="somefield" validate="minlength=1" /></code></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>none</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>–</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Does nothing (used to override a @Validate annotation)</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code><t:textfield value="somefield" validate="none" /></code></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>rege
xp</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>pattern</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Makes sure that a string value conforms to a given pattern</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code><t:textfield value="letterfield" validate="regexp=^</code><code>[A-Za-z]+$" /></code></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>required</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>–</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Makes sure that a string value is not null and not the empty string</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code><t:textfield value="name" validate="required" /></code></p></td></tr></tbody></table></div><h2 id="FormsandValidation-CentralizingValidationwith@Validate">Centralizing Validation with @Validate</h2><p>The @<a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/b
eaneditor/Validate.html">Validate</a> annotation can take the place of the validate parameter of TextField, PasswordField, TextArea and other components. When the validate parameter is not bound in the template file, the component will check for the @Validate annotation and use its value as the validation definition.</p><p>The annotation may be placed on the getter or setter method, or on the field itself.</p><p>Let's update the two fields of the Login page:</p><parameter ac:name="language">java</parameter><plain-text-body> @Persist
+</div></pre>
+</div></div><p> </p><p><span style="color: rgb(83,145,38);font-size: 24.0px;line-height: 1.25;">Form Validation</span></p><p>The above example is a very basic form which allows the fields to be empty. However, with a little more effort we can add client-side validation to prevent the user from submitting the form with either field empty.</p><p>Validation in Tapestry involves associating one or more <em>validators</em> with a form element component, such as TextField or PasswordField. This is done using the <strong>validate</strong> parameter:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<pre class="brush: xml; gutter: false; theme: Default" style="font-size:12px;"><t:textfield t:id="userName" validate="required" t:mixins="formgroup"/>
+<t:passwordfield t:id="password" value="password" validate="required" t:mixins="formgroup"/></pre>
+</div></div><p> </p><p><span style="color: rgb(83,145,38);font-size: 20.0px;line-height: 1.5;">Available Validators</span></p><p>Tapestry provides the following built-in validators:</p><div class="table-wrap"><table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1" class="confluenceTh"><p>Validator</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>Constraint Type</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>Description</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>Example</p></th></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>email</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>–</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Ensures that the given input looks like a valid e-mail address</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code><t:textfield value="email" validate="email" /></code></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>ma
x</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>long</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Enforces a maximum integer value</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code><t:textfield value="age" validate="max=120,min=0" /></code></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>maxLength</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>int</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Makes sure that a string value has a maximum length</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code><t:textfield value="zip" validate="maxlength=7" /></code></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>min</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>long</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Enforces a minimum integer value</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code><t:textfield value="
age" validate="max=120,min=0" /></code></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>minLength</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>int</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Makes sure that a string value has a minimum length</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code><t:textfield value="somefield" validate="minlength=1" /></code></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>none</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>–</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Does nothing (used to override a @Validate annotation)</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code><t:textfield value="somefield" validate="none" /></code></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>regexp</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>pattern</p></td><td colspan="1" rowspan="
1" class="confluenceTd"><p>Makes sure that a string value conforms to a given pattern</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code><t:textfield value="letterfield" validate="regexp=^</code><code>[A-Za-z]+$" /></code></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>required</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>–</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Makes sure that a string value is not null and not the empty string</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code><t:textfield value="name" validate="required" /></code></p></td></tr></tbody></table></div><h2 id="FormsandValidation-CentralizingValidationwith@Validate">Centralizing Validation with @Validate</h2><p>The @<a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/beaneditor/Validate.html">Validate</a> annotation can take the place of the validate parameter of TextFie
ld, PasswordField, TextArea and other components. When the validate parameter is not bound in the template file, the component will check for the @Validate annotation and use its value as the validation definition.</p><p>The annotation may be placed on the getter or setter method, or on the field itself.</p><p>Let's update the two fields of the Login page:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> @Persist
@Property
@Validate("required")
private String userName;
@Property
@Validate("required")
- private String password;</plain-text-body><p>Now, we'll rebuild the app, refresh the browser, and just hit enter:</p><p><span class="confluence-embedded-file-wrapper image-center-wrapper confluence-embedded-manual-size"><img class="confluence-embedded-image confluence-content-image-border image-center" width="500" src="forms-and-validation.data/newapp_com_example.png"></span></p><p>The form has updated, in place, to present the errors. You will not be able to submit the form until some value is provided for each field.</p><h2 id="FormsandValidation-ServerSideValidation">Server Side Validation</h2><p>Some validation can't, or shouldn't, be done on the client side. How do we know if the password is correct? Short of downloading all users and passwords to the client, we really need to do the validation on the server.</p><p>In fact, all client-side validation (via the validate parameter, or @Validate annotation) is performed again on the server.</p><p>It is also possible to perfor
m extra validation there.</p><parameter ac:name="language">java</parameter><plain-text-body> /**
+ private String password;</pre>
+</div></div><p>Now, we'll rebuild the app, refresh the browser, and just hit enter:</p><p><span class="confluence-embedded-file-wrapper image-center-wrapper confluence-embedded-manual-size"><img class="confluence-embedded-image confluence-content-image-border image-center" width="500" src="forms-and-validation.data/newapp_com_example.png"></span></p><p>The form has updated, in place, to present the errors. You will not be able to submit the form until some value is provided for each field.</p><h2 id="FormsandValidation-ServerSideValidation">Server Side Validation</h2><p>Some validation can't, or shouldn't, be done on the client side. How do we know if the password is correct? Short of downloading all users and passwords to the client, we really need to do the validation on the server.</p><p>In fact, all client-side validation (via the validate parameter, or @Validate annotation) is performed again on the server.</p><p>It is also possible to perform extra validation there.</p><d
iv class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> /**
* Do the cross-field validation
*/
void onValidateFromLoginForm() {
@@ -160,22 +232,34 @@ Note that the onValidateFromLoginForm()
}
}
-</plain-text-body><p>This is the validate event handler from the loginForm component. It is invoked once all the components have had a chance to read values out of the request, do their own validations, and update the properties they are bound to.</p><p>In this case, the authenticator is used to decide if the userName and password is valid. In a real application, this would be where a database or other external service was consulted.</p><p>If the combination is not valid, then the password field is marked as in error. The form is used to record an error, about a component (the passwordField) with an error message.</p><p>Entering any two values into the form and submitting will cause a round trip; the form will re-render to present the error to the user:</p><p><span class="confluence-embedded-file-wrapper image-center-wrapper confluence-embedded-manual-size"><img class="confluence-embedded-image confluence-content-image-border image-center" width="500" src="forms-and-validation.data/
newapp_com_example.png"></span></p><p>Notice that the cursor is placed directly into the password field.</p><rich-text-body><p>In versions of Tapestry prior to 5.4, a form with validation errors would result in a redirect response to the client; often, temporary server-side data (such as the userName field) would be lost. Starting in 5.4, submitting a form with validation errors results in the new page being rendered in the same request as the form submission.</p></rich-text-body><p> </p><h2 id="FormsandValidation-CustomizingValidationMessages">Customizing Validation Messages</h2><p>Each validator (such as "required" or "minlength") has a default message used (on the client side and the server side) when the constraint is violated; that is, when the user input is not valid.</p><p>The message can be customized by adding an entry to the page's <a href="localization.html">message catalog</a> (or the containing component's message catalog). As with any localized property, this can
also go into the application's message catalog.</p><p>The first key checked is <em>formId</em>-<em>fieldId</em>-<em>validatorName</em>-message.</p><ul><li>formId: the local component id of the Form component</li><li>fieldId: the local component id of the field (TextField, etc.)</li><li>validatorName: the name of the validator, i.e., "required" or "minlength"</li></ul><p>If there is no message for that key, a second check is made, for <em>fieldId</em>-<em>validatorName</em>-message. <span style="font-size: 14.0px;">If</span><span style="font-size: 14.0px;"> that does not match a message, then the built-in default validation message is used.</span></p><p><span style="font-size: 14.0px;">For example, if the form ID is "loginForm", the field ID is "userName", and the validator is "required" then Tapestry will first look for a "loginForm-userName-required-message" key in the message catalog, and then for a "<span>userName-required-message" key.</span></span></p><p>The validati
on message in the message catalog may contain <a class="external-link" href="https://docs.oracle.com/javase/7/docs/api/java/util/Formatter.html" rel="nofollow">printf-style format strings</a> (such as %s) to indicate where the validate parameter's value will be inserted. For example, if the validate parameter in the template is minLength=3 and the validation message is "User name must be at least %s characters" then the corresponding error message would be <span>"User name must be at least 5 characters".</span></p><h3 id="FormsandValidation-CustomizingValidationMessagesforBeanEditForm">Customizing Validation Messages for BeanEditForm</h3><p>The <a href="beaneditform-guide.html">BeanEditForm</a> component also supports validation message customizing. The search for messages is similar; the <em>formId</em> is the component id of the BeanEditForm component (not the Form component it contains). The <em>fieldId</em> is the property name.</p><h2 id="FormsandValidation-Configur
ingValidatorContraintsintheMessageCatalog">Configuring Validator Contraints in the Message Catalog</h2><p>It is possible to omit the validation constraint from the validate parameter (or @Validator annotation), in which case it is expected to be stored in the message catalog.</p><p>This is useful when the validation constraint is awkward to enter inline, such as a regular expression for use with the regexp validator.</p><p>The key here is similar to customizing the validation message: <em>formId</em>-<em>fieldId</em>-<em>validatorName</em> or just <em>fieldId</em>-<em>validatorName</em>.</p><p>For example, your template may have the following:</p><parameter ac:name="language">xml</parameter><plain-text-body> <t:textfield t:id="ssn" validate="required,regexp"/>
-</plain-text-body><p>And your message catalog can contain:</p><parameter ac:name="language">java</parameter><plain-text-body>ssn-regexp=\d{3}-\d{2}-\d{4}
+</pre>
+</div></div><p>This is the validate event handler from the loginForm component. It is invoked once all the components have had a chance to read values out of the request, do their own validations, and update the properties they are bound to.</p><p>In this case, the authenticator is used to decide if the userName and password is valid. In a real application, this would be where a database or other external service was consulted.</p><p>If the combination is not valid, then the password field is marked as in error. The form is used to record an error, about a component (the passwordField) with an error message.</p><p>Entering any two values into the form and submitting will cause a round trip; the form will re-render to present the error to the user:</p><p><span class="confluence-embedded-file-wrapper image-center-wrapper confluence-embedded-manual-size"><img class="confluence-embedded-image confluence-content-image-border image-center" width="500" src="forms-and-validation.data/newapp
_com_example.png"></span></p><p>Notice that the cursor is placed directly into the password field.</p><div class="confluence-information-macro confluence-information-macro-note"><span class="aui-icon aui-icon-small aui-iconfont-warning confluence-information-macro-icon"></span><div class="confluence-information-macro-body"><p>In versions of Tapestry prior to 5.4, a form with validation errors would result in a redirect response to the client; often, temporary server-side data (such as the userName field) would be lost. Starting in 5.4, submitting a form with validation errors results in the new page being rendered in the same request as the form submission.</p></div></div><p> </p><h2 id="FormsandValidation-CustomizingValidationMessages">Customizing Validation Messages</h2><p>Each validator (such as "required" or "minlength") has a default message used (on the client side and the server side) when the constraint is violated; that is, when the user input is not valid.</p><p>The m
essage can be customized by adding an entry to the page's <a href="localization.html">message catalog</a> (or the containing component's message catalog). As with any localized property, this can also go into the application's message catalog.</p><p>The first key checked is <em>formId</em>-<em>fieldId</em>-<em>validatorName</em>-message.</p><ul><li>formId: the local component id of the Form component</li><li>fieldId: the local component id of the field (TextField, etc.)</li><li>validatorName: the name of the validator, i.e., "required" or "minlength"</li></ul><p>If there is no message for that key, a second check is made, for <em>fieldId</em>-<em>validatorName</em>-message. <span style="font-size: 14.0px;">If</span><span style="font-size: 14.0px;"> that does not match a message, then the built-in default validation message is used.</span></p><p><span style="font-size: 14.0px;">For example, if the form ID is "loginForm", the field ID is "userName", and the validator is "re
quired" then Tapestry will first look for a "loginForm-userName-required-message" key in the message catalog, and then for a "<span>userName-required-message" key.</span></span></p><p>The validation message in the message catalog may contain <a class="external-link" href="https://docs.oracle.com/javase/7/docs/api/java/util/Formatter.html" rel="nofollow">printf-style format strings</a> (such as %s) to indicate where the validate parameter's value will be inserted. For example, if the validate parameter in the template is minLength=3 and the validation message is "User name must be at least %s characters" then the corresponding error message would be <span>"User name must be at least 5 characters".</span></p><h3 id="FormsandValidation-CustomizingValidationMessagesforBeanEditForm">Customizing Validation Messages for BeanEditForm</h3><p>The <a href="beaneditform-guide.html">BeanEditForm</a> component also supports validation message customizing. The search for messages is si
milar; the <em>formId</em> is the component id of the BeanEditForm component (not the Form component it contains). The <em>fieldId</em> is the property name.</p><h2 id="FormsandValidation-ConfiguringValidatorContraintsintheMessageCatalog">Configuring Validator Contraints in the Message Catalog</h2><p>It is possible to omit the validation constraint from the validate parameter (or @Validator annotation), in which case it is expected to be stored in the message catalog.</p><p>This is useful when the validation constraint is awkward to enter inline, such as a regular expression for use with the regexp validator.</p><p>The key here is similar to customizing the validation message: <em>formId</em>-<em>fieldId</em>-<em>validatorName</em> or just <em>fieldId</em>-<em>validatorName</em>.</p><p>For example, your template may have the following:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<pre class="brush: xml; gutter: false; theme: Default" style="font-size:12px;"> <t:textfield t:id="ssn" validate="required,regexp"/>
+</pre>
+</div></div><p>And your message catalog can contain:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">ssn-regexp=\d{3}-\d{2}-\d{4}
ssn-regexp-message=Social security numbers are in the format 12-34-5678.
-</plain-text-body><p>This technique also works with the BeanEditForm; as with validation messages, the formId is the BeanEditForm component's id, and the fieldId is the name of the property being editted.</p><h2 id="FormsandValidation-ValidationMacros">Validation Macros</h2>
+</pre>
+</div></div><p>This technique also works with the BeanEditForm; as with validation messages, the formId is the BeanEditForm component's id, and the fieldId is the name of the property being editted.</p><h2 id="FormsandValidation-ValidationMacros">Validation Macros</h2>
<div class="confluence-information-macro confluence-information-macro-information"><p class="title">Added in 5.2</p><span class="aui-icon aui-icon-small aui-iconfont-info confluence-information-macro-icon"></span><div class="confluence-information-macro-body">
</div></div>
<div class="error"><span class="error">Unknown macro: {div}</span>
-<p> </p></div><p>Lists of validators can be combined into <em>validation macros</em>. This mechanism is convenient for ensuring consistent validation rules across an application. To create a validation macro, just contribute to the ValidatorMacro Service in your module class (normally AppModule.java), by adding a new entry to the configuration object, as shown below. The first parameter is the name of your macro, the second is a comma-separated list of validators:</p><parameter ac:name="language">java</parameter><plain-text-body>@Contribute(ValidatorMacro.class)
+<p> </p></div><p>Lists of validators can be combined into <em>validation macros</em>. This mechanism is convenient for ensuring consistent validation rules across an application. To create a validation macro, just contribute to the ValidatorMacro Service in your module class (normally AppModule.java), by adding a new entry to the configuration object, as shown below. The first parameter is the name of your macro, the second is a comma-separated list of validators:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">@Contribute(ValidatorMacro.class)
public static void combinePasswordValidators(MappedConfiguration<String, String> configuration) {
configuration.add("password","required,minlength=5,maxlength=15,");
}
-</plain-text-body><p>Then, you can use this new macro in component templates and classes:</p><parameter ac:name="language">xml</parameter><plain-text-body><input t:type="textField" t:id="password" t:validate="password" />
-</plain-text-body><parameter ac:name="language">java</parameter><plain-text-body>@Validate("password")
+</pre>
+</div></div><p>Then, you can use this new macro in component templates and classes:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<pre class="brush: xml; gutter: false; theme: Default" style="font-size:12px;"><input t:type="textField" t:id="password" t:validate="password" />
+</pre>
+</div></div><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">@Validate("password")
private String password;
-</plain-text-body><h2 id="FormsandValidation-OverridingtheTranslatorwithEvents">Overriding the Translator with Events</h2><p>The TextField, PasswordField and TextArea components all have a translate parameter, a <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/FieldTranslator.html">FieldTranslator</a> object that is used to convert values on the server side to strings on the client side.</p><p>In most cases, the translate parameter is not set explicitly; Tapestry derives an appropriate value based on the type of property being editted by the field.</p><p>In certain cases, you may want to override the translator. This can be accomplished using two events triggered on the component, "toclient" and "parseclient".</p><p>The "toclient" event is passed the current object value and returns a string, which will be the default value for the field. When there is no event handler, or when the event handler returns null, the default Translator is u
sed to convert the server side value to a string.</p><p>For example, you may have a quantity field that you wish to display as blank, rather than zero, initially:</p><parameter ac:name="language">java</parameter><plain-text-body> <t:textfield t:id="quantity" size="10"/>
+</pre>
+</div></div><h2 id="FormsandValidation-OverridingtheTranslatorwithEvents">Overriding the Translator with Events</h2><p>The TextField, PasswordField and TextArea components all have a translate parameter, a <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/FieldTranslator.html">FieldTranslator</a> object that is used to convert values on the server side to strings on the client side.</p><p>In most cases, the translate parameter is not set explicitly; Tapestry derives an appropriate value based on the type of property being editted by the field.</p><p>In certain cases, you may want to override the translator. This can be accomplished using two events triggered on the component, "toclient" and "parseclient".</p><p>The "toclient" event is passed the current object value and returns a string, which will be the default value for the field. When there is no event handler, or when the event handler returns null, the default Translator is used to
convert the server side value to a string.</p><p>For example, you may have a quantity field that you wish to display as blank, rather than zero, initially:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> <t:textfield t:id="quantity" size="10"/>
. . .
@@ -187,17 +271,22 @@ private String password;
return null;
}
-</plain-text-body><p>This is good so far, but if the field is optional and the user submits the form, you'll get a validation error, because the empty string is not valid as an integer.</p><p>That's where the "parseclient" event comes in:</p><parameter ac:name="language">java</parameter><plain-text-body> Object onParseClientFromQuantity(String input)
+</pre>
+</div></div><p>This is good so far, but if the field is optional and the user submits the form, you'll get a validation error, because the empty string is not valid as an integer.</p><p>That's where the "parseclient" event comes in:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> Object onParseClientFromQuantity(String input)
{
if ("".equals(input)) return 0;
return null;
}
-</plain-text-body><p>The event handler method has precedence over the translator. Here it checks for the empty string (and note that the input may be null!) and evaluates that as zero.</p><p>Again, returning null lets the normal translator do its work.</p><p>The event handler may also throw a <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/ValidationException.html">ValidationException</a> to indicate a value that can't be parsed.</p><p>Now, what if you want to perform your own custom validation? That's another event: "validate":</p><parameter ac:name="language">java</parameter><plain-text-body> void onValidateFromCount(Integer value) throws ValidationException
+</pre>
+</div></div><p>The event handler method has precedence over the translator. Here it checks for the empty string (and note that the input may be null!) and evaluates that as zero.</p><p>Again, returning null lets the normal translator do its work.</p><p>The event handler may also throw a <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/ValidationException.html">ValidationException</a> to indicate a value that can't be parsed.</p><p>Now, what if you want to perform your own custom validation? That's another event: "validate":</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> void onValidateFromCount(Integer value) throws ValidationException
{
if (value.equals(13)) throw new ValidationException("Thirteen is an unlucky number.");
}
-</plain-text-body><p>This event gets fired <strong>after</strong> the normal validators. It is passed the <em>parsed</em> value (not the string from the client, but the object value from the translator, or from the "parseclient" event handler).</p><p>The method may not return a value, but may throw a ValidationException to indicate a problem with the value.</p><p><strong>Caution:</strong> These events are exclusively on the <em>server side</em>. This means that, in certain circumstances, an input value will be rejected on the client side even though it is valid on the server side. You may need to disable client-side validation in order to use this feature.</p></div>
+</pre>
+</div></div><p>This event gets fired <strong>after</strong> the normal validators. It is passed the <em>parsed</em> value (not the string from the client, but the object value from the translator, or from the "parseclient" event handler).</p><p>The method may not return a value, but may throw a ValidationException to indicate a problem with the value.</p><p><strong>Caution:</strong> These events are exclusively on the <em>server side</em>. This means that, in certain circumstances, an input value will be rejected on the client side even though it is valid on the server side. You may need to disable client-side validation in order to use this feature.</p></div>
</div>
<div class="clearer"></div>
Modified: websites/production/tapestry/content/general-questions.html
==============================================================================
--- websites/production/tapestry/content/general-questions.html (original)
+++ websites/production/tapestry/content/general-questions.html Sat Sep 16 01:54:19 2017
@@ -27,6 +27,16 @@
</title>
<link type="text/css" rel="stylesheet" href="/resources/space.css" />
+ <link href='/resources/highlighter/styles/shCoreCXF.css' rel='stylesheet' type='text/css' />
+ <link href='/resources/highlighter/styles/shThemeCXF.css' rel='stylesheet' type='text/css' />
+ <script src='/resources/highlighter/scripts/shCore.js' type='text/javascript'></script>
+ <script src='/resources/highlighter/scripts/shBrushJava.js' type='text/javascript'></script>
+ <script src='/resources/highlighter/scripts/shBrushXml.js' type='text/javascript'></script>
+ <script src='/resources/highlighter/scripts/shBrushPlain.js' type='text/javascript'></script>
+ <script>
+ SyntaxHighlighter.defaults['toolbar'] = false;
+ SyntaxHighlighter.all();
+ </script>
<link href="/styles/style.css" rel="stylesheet" type="text/css"/>
@@ -67,7 +77,16 @@
</div>
<div id="content">
- <div id="ConfluenceContent"><plain-text-body>{scrollbar}</plain-text-body><h2 id="GeneralQuestions-GeneralQuestions">General Questions</h2><p></p><h3 id="GeneralQuestions-HowdoIgetstartedwithTapestry?">How do I get started with Tapestry?</h3><p>The easiest way to get started is to use <a class="external-link" href="http://maven.apache.org">Apache Maven</a> to create your initial project; Maven can use an <em>archetype</em> (a kind of project template) to create a bare-bones Tapestry application for you. See the <a href="getting-started.html">Getting Started</a> page for more details.</p><p>Even without Maven, Tapestry is quite easy to set up. You just need to <a href="download.html">download</a> the binaries and setup your build to place them inside your WAR's WEB-INF/lib folder. The rest is just some one-time <a href="configuration.html">configuration of the web.xml deployment descriptor</a>.</p><h3 id="GeneralQuestions-WhydoesTapestryusePrototype?Whynotinsertfa
voriteJavaScriptlibraryhere?">Why does Tapestry use Prototype? Why not <em>insert favorite JavaScript library here</em>?</h3><p>An important goal for Tapestry is seamless DHTML and Ajax integration. To serve that goal, it was important that the built in components be capable of Ajax operations, such as dynamically re-rendering parts of the page. Because of that, it made sense to bundle a well-known JavaScript library as part of Tapestry.</p><p>At the time (this would be 2006-ish), Prototype and Scriptaculous were well known and well documented, and jQuery was just getting started.</p><p>The intent has always been to make this aspect of Tapestry pluggable. Tapestry 5.4 includes the option of either Prototype or jQuery Tapestry 5.5 will remove Prototype as an option..</p><h3 id="GeneralQuestions-WhydoesTapestryhaveitsownInversionofControlContainer?WhynotSpringorGuice?">Why does Tapestry have its own Inversion of Control Container? Why not Spring or Guice?</h3><p>An Inversion of Contro
l Container is <em>the</em> key piece of Tapestry's infrastructure. It is absolutely necessary to create software as robust, performant ,and extensible as Tapestry.</p><p>Tapestry IoC includes a number of features that distinguish itself from other containers:</p><ul><li>Configured in code, not XML</li><li>Built-in extension mechanism for services: configurations and contributions</li><li>Built-in aspect oriented programming model (service decorations and advice)</li><li>Easy modularization</li><li>Best-of-breed exception reporting</li></ul><p>Because Tapestry is implemented on top of its IoC container, and because the container makes it easy to extend or replace any service inside the container, it is possible to make the small changes to Tapestry needed to customize it to any project's needs.</p><h3 id="GeneralQuestions-HowdoIupgradefromTapestry4toTapestry5?">How do I upgrade from Tapestry 4 to Tapestry 5?</h3><p>There is no existing tool that supports upgrading from Tapestry 4 to
Tapestry 5; Tapestry 5 is a complete rewrite.</p><p>Many of the basic concepts in Tapestry 4 are still present in Tapestry 5, but refactored, improved, streamlined, and simplified. The basic concept of pages, templates and components are largely the same. Other aspects, such as server-side event handling, is markedly different.</p><h3 id="GeneralQuestions-HowdoIupgradefromoneversionofTapestry5toanother?">How do I upgrade from one version of Tapestry 5 to another?</h3><p>A lot of effort goes into making an upgrade from one Tapestry 5 release to another go smoothly. In the general case, it is just a matter of updating the version number in your Maven <code>build.xml</code> or Gradle <code>build.gradle</code> file and executing the appropriate commands (e.g., <code>gradle idea</code> or <code>mvn eclipse:eclipse</code>) to bring your local workspace up to date with the latest binaries.</p><p>After changing dependencies, you should always perform a clean recompile of your application.<
/p><p>We make every effort to ensure backwards-compatibility. Tapestry is mostly coded in terms of interfaces; those interfaces are stable to a point: interfaces your code is expected to implement are usually completely frozen; interfaces your code is expected to invoke, such as the interfaces to IoC services, are stable, but may have new methods added in a release; existing methods are not changed.</p><p>In <em>rare</em> cases a choice is necessary between fixing bugs (or adding essential functionality) and maintaining complete backwards compatibility; in those cases, an incompatible change may be introduced. These are always discussed in detail in the <a href="release-notes.html">Release Notes</a> for the specific release. You should always read the release notes before attempting an upgrade, and always (really, <em>always</em>) be prepared to retest your application afterwards.</p><p>Note that you should be careful any time you make use of <strong>internal</strong> APIs (you can
tell an API is internal by the package name, <code>org.apache.tapestry5.internal...</code>. Internal APIs may change <em>at any time</em>; there's no guarantee of backwards compatibility. Please always check on the documentation, or consult the user mailing list, to see if there's a stable, public alternative. If you do make use of internal APIs, be sure to get a discussion going so that your needs can be met in the future by a stable, public API.</p><p><span style="color: rgb(83,145,38);font-size: 16.0px;line-height: 1.5625;">Why are there both Request and HttpServletRequest?</span></p><p>Tapestry's Request interface is <em>very</em> close to the standard HttpServletRequest interface. It differs in a few ways, omitting some unneeded methods, and adding a couple of new methods (such as <code>isXHR()</code>), as well as changing how some existing methods operate. For example, <code>getParameterNames()</code> returns a sorted List of Strings; HttpServletRequest returns an Enumeration
, which is a very dated approach.</p><p>However, the stronger reason for Request (and the related interfaces Response and Session) is to enable the support for Portlets at some point in the future. By writing code in terms of Tapestry's Request, and not HttpServletRequest, you can be assured that the same code will operate in both Servlet Tapestry and Portlet Tapestry.</p><plain-text-body>{scrollbar}</plain-text-body></div>
+ <div id="ConfluenceContent"><h2 id="GeneralQuestions-GeneralQuestions">General Questions</h2><p><style type="text/css">/*<![CDATA[*/
+div.rbtoc1499639545088 {padding: 0px;}
+div.rbtoc1499639545088 ul {list-style: disc;margin-left: 0px;}
+div.rbtoc1499639545088 li {margin-left: 0px;padding-left: 0px;}
+
+/*]]>*/</style></p><div class="toc-macro rbtoc1499639545088">
+<ul class="toc-indentation"><li><a href="#GeneralQuestions-GeneralQuestions">General Questions</a>
+<ul class="toc-indentation"><li><a href="#GeneralQuestions-HowdoIgetstartedwithTapestry?">How do I get started with Tapestry?</a></li><li><a href="#GeneralQuestions-WhydoesTapestryusePrototype?WhynotinsertfavoriteJavaScriptlibraryhere?">Why does Tapestry use Prototype? Why not insert favorite JavaScript library here?</a></li><li><a href="#GeneralQuestions-WhydoesTapestryhaveitsownInversionofControlContainer?WhynotSpringorGuice?">Why does Tapestry have its own Inversion of Control Container? Why not Spring or Guice?</a></li><li><a href="#GeneralQuestions-HowdoIupgradefromTapestry4toTapestry5?">How do I upgrade from Tapestry 4 to Tapestry 5?</a></li><li><a href="#GeneralQuestions-HowdoIupgradefromoneversionofTapestry5toanother?">How do I upgrade from one version of Tapestry 5 to another?</a></li></ul>
+</li></ul>
+</div><h3 id="GeneralQuestions-HowdoIgetstartedwithTapestry?">How do I get started with Tapestry?</h3><p>The easiest way to get started is to use <a class="external-link" href="http://maven.apache.org">Apache Maven</a> to create your initial project; Maven can use an <em>archetype</em> (a kind of project template) to create a bare-bones Tapestry application for you. See the <a href="getting-started.html">Getting Started</a> page for more details.</p><p>Even without Maven, Tapestry is quite easy to set up. You just need to <a href="download.html">download</a> the binaries and setup your build to place them inside your WAR's WEB-INF/lib folder. The rest is just some one-time <a href="configuration.html">configuration of the web.xml deployment descriptor</a>.</p><h3 id="GeneralQuestions-WhydoesTapestryusePrototype?WhynotinsertfavoriteJavaScriptlibraryhere?">Why does Tapestry use Prototype? Why not <em>insert favorite JavaScript library here</em>?</h3><p>An important goal for Tapest
ry is seamless DHTML and Ajax integration. To serve that goal, it was important that the built in components be capable of Ajax operations, such as dynamically re-rendering parts of the page. Because of that, it made sense to bundle a well-known JavaScript library as part of Tapestry.</p><p>At the time (this would be 2006-ish), Prototype and Scriptaculous were well known and well documented, and jQuery was just getting started.</p><p>The intent has always been to make this aspect of Tapestry pluggable. Tapestry 5.4 includes the option of either Prototype or jQuery Tapestry 5.5 will remove Prototype as an option..</p><h3 id="GeneralQuestions-WhydoesTapestryhaveitsownInversionofControlContainer?WhynotSpringorGuice?">Why does Tapestry have its own Inversion of Control Container? Why not Spring or Guice?</h3><p>An Inversion of Control Container is <em>the</em> key piece of Tapestry's infrastructure. It is absolutely necessary to create software as robust, performant ,and extensible as T
apestry.</p><p>Tapestry IoC includes a number of features that distinguish itself from other containers:</p><ul><li>Configured in code, not XML</li><li>Built-in extension mechanism for services: configurations and contributions</li><li>Built-in aspect oriented programming model (service decorations and advice)</li><li>Easy modularization</li><li>Best-of-breed exception reporting</li></ul><p>Because Tapestry is implemented on top of its IoC container, and because the container makes it easy to extend or replace any service inside the container, it is possible to make the small changes to Tapestry needed to customize it to any project's needs.</p><h3 id="GeneralQuestions-HowdoIupgradefromTapestry4toTapestry5?">How do I upgrade from Tapestry 4 to Tapestry 5?</h3><p>There is no existing tool that supports upgrading from Tapestry 4 to Tapestry 5; Tapestry 5 is a complete rewrite.</p><p>Many of the basic concepts in Tapestry 4 are still present in Tapestry 5, but refactored, improved, str
eamlined, and simplified. The basic concept of pages, templates and components are largely the same. Other aspects, such as server-side event handling, is markedly different.</p><h3 id="GeneralQuestions-HowdoIupgradefromoneversionofTapestry5toanother?">How do I upgrade from one version of Tapestry 5 to another?</h3><p>A lot of effort goes into making an upgrade from one Tapestry 5 release to another go smoothly. In the general case, it is just a matter of updating the version number in your Maven <code>build.xml</code> or Gradle <code>build.gradle</code> file and executing the appropriate commands (e.g., <code>gradle idea</code> or <code>mvn eclipse:eclipse</code>) to bring your local workspace up to date with the latest binaries.</p><p>After changing dependencies, you should always perform a clean recompile of your application.</p><p>We make every effort to ensure backwards-compatibility. Tapestry is mostly coded in terms of interfaces; those interfaces are stable to a point: inter
faces your code is expected to implement are usually completely frozen; interfaces your code is expected to invoke, such as the interfaces to IoC services, are stable, but may have new methods added in a release; existing methods are not changed.</p><p>In <em>rare</em> cases a choice is necessary between fixing bugs (or adding essential functionality) and maintaining complete backwards compatibility; in those cases, an incompatible change may be introduced. These are always discussed in detail in the <a href="release-notes.html">Release Notes</a> for the specific release. You should always read the release notes before attempting an upgrade, and always (really, <em>always</em>) be prepared to retest your application afterwards.</p><p>Note that you should be careful any time you make use of <strong>internal</strong> APIs (you can tell an API is internal by the package name, <code>org.apache.tapestry5.internal...</code>. Internal APIs may change <em>at any time</em>; there's no guara
ntee of backwards compatibility. Please always check on the documentation, or consult the user mailing list, to see if there's a stable, public alternative. If you do make use of internal APIs, be sure to get a discussion going so that your needs can be met in the future by a stable, public API.</p><p><span style="color: rgb(83,145,38);font-size: 16.0px;line-height: 1.5625;">Why are there both Request and HttpServletRequest?</span></p><p>Tapestry's Request interface is <em>very</em> close to the standard HttpServletRequest interface. It differs in a few ways, omitting some unneeded methods, and adding a couple of new methods (such as <code>isXHR()</code>), as well as changing how some existing methods operate. For example, <code>getParameterNames()</code> returns a sorted List of Strings; HttpServletRequest returns an Enumeration, which is a very dated approach.</p><p>However, the stronger reason for Request (and the related interfaces Response and Session) is to enable the support
for Portlets at some point in the future. By writing code in terms of Tapestry's Request, and not HttpServletRequest, you can be assured that the same code will operate in both Servlet Tapestry and Portlet Tapestry.</p></div>
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