svn commit: r946234 [3/3] - in /websites/production/tapestry/content: ./ cache/ development-dashboard.data/ forms-and-validation.data/

[bu...@apache.org]

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 Fri Apr  3 20:19:44 2015
@@ -98,14 +98,14 @@
                             </div>
         </li></ul>
 </div><p>The life's blood of any application is form input; this is the most effective way to gather significant information from the user. Whether it's a search form, a login screen or a multi-page registration wizard, forms are how the user really expresses themselves to the application.</p><p>Tapestry excels at creating forms and validating input. 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 (once implemented) on the client as well.</p><p>Finally, Tapestry is able to not only present the errors back to the user, but to decorate the fields and the labels for the fields, marking them as containing errors (primarily, using CSS effects).</p><p><strong>Contents</strong></p><p><style type="text/css">/*<![CDATA[*/
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 <ul class="toc-indentation"><li>Related Articles</li></ul>
 <ul><li><a shape="rect" href="#FormsandValidation-TheFormComponent">The Form Component</a>
-<ul class="toc-indentation"><li><a shape="rect" href="#FormsandValidation-FormEvents">Form Events</a></li><li><a shape="rect" href="#FormsandValidation-TrackingValidationErrors">Tracking Validation Errors</a></li><li><a shape="rect" href="#FormsandValidation-StoringDataBetweenRequests">Storing Data Between Requests</a></li><li><a shape="rect" href="#FormsandValidation-ConfiguringFieldsandLabels">Configuring Fields and Labels</a></li><li><a shape="rect" href="#FormsandValidation-CentralizingValidationwith@Validate">Centralizing Validation with @Validate</a></li><li><a shape="rect" href="#FormsandValidation-CustomizingValidationMessages">Customizing Validation Messages</a>
+<ul class="toc-indentation"><li><a shape="rect" href="#FormsandValidation-FormEvents">Form Events</a></li><li><a shape="rect" href="#FormsandValidation-TrackingValidationErrors">Tracking Validation Errors</a></li><li><a shape="rect" href="#FormsandValidation-StoringDataBetweenRequests">Storing Data Between Requests</a></li><li><a shape="rect" href="#FormsandValidation-ConfiguringFieldsandLabels">Configuring Fields and Labels</a></li><li><a shape="rect" href="#FormsandValidation-CentralizingValidationwith@Validate">Centralizing Validation with @Validate</a></li><li><a shape="rect" href="#FormsandValidation-ServerSideValidation">Server Side Validation</a></li><li><a shape="rect" href="#FormsandValidation-CustomizingValidationMessages">Customizing Validation Messages</a>
 <ul class="toc-indentation"><li><a shape="rect" href="#FormsandValidation-CustomizingValidationMessagesforBeanEditForm">Customizing Validation Messages for BeanEditForm</a></li></ul>
 </li><li><a shape="rect" href="#FormsandValidation-ConfiguringValidatorContraintsintheMessageCatalog">Configuring Validator Contraints in the Message Catalog</a></li><li><a shape="rect" href="#FormsandValidation-ValidationMacros">Validation Macros</a></li><li><a shape="rect" href="#FormsandValidation-OverridingtheTranslatorwithEvents">Overriding the Translator with Events</a></li></ul>
 </li></ul></div><h1 id="FormsandValidation-TheFormComponent">The Form Component</h1><p>The core of Tapestry's form support is the <a shape="rect" 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 shape="rect" class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/TextField.html">TextField</a>, <a shape="rect" class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/TextArea.html">TextArea</a>, <a shape="rect" 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 shape="rect" href="component-events.html">
 component events</a>. You'll need to provide event handler methods for some of these.</p><p>When rendering, the Form component emits two notifications: first, "prepareForRender", then "prepare". These allow the Form's container to setup 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" notification, then a "prepare" notification. 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 activated 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">
@@ -197,7 +197,7 @@ public class Login {
 
 &lt;/html&gt;
 ]]></script>
-</div></div><p>Rendering the page gives a reasonable pleasing first pass:</p><p><img class="confluence-embedded-image confluence-content-image-border image-center" width="500" src="forms-and-validation.data/newapp_com_example.png" data-image-src="/confluence/download/attachments/22872109/newapp_com_example.png?version=2&amp;modificationDate=1428088329843&amp;api=v2"></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.&#160;</span></p><p>As a rule of thumb, you should always give your fields a specific id (this id will be used to generat
 e the <code>name</code> and <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 &lt;label&gt; 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">
+</div></div><p>Rendering the page gives a reasonable pleasing first pass:</p><p><img class="confluence-embedded-image confluence-content-image-border image-center" width="500" src="forms-and-validation.data/newapp_com_example.png" data-image-src="/confluence/download/attachments/22872109/newapp_com_example.png?version=3&amp;modificationDate=1428088849224&amp;api=v2"></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.&#160;</span></p><p>As a rule of thumb, you should always give your fields a specific id (this id will be used to generat
 e the <code>name</code> and <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 &lt;label&gt; 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">
 <script class="theme: Default; brush: xml; gutter: false" type="syntaxhighlighter"><![CDATA[&lt;div class=&quot;form-group&quot;&gt;
   &lt;label for=&quot;userName&quot; class=&quot;control-label&quot;&gt;User Name&lt;/label&gt;
   &lt;input id=&quot;userName&quot; class=&quot;form-control&quot; name=&quot;userName&quot; type=&quot;text&quot;&gt;
@@ -211,7 +211,25 @@ public class Login {
   @Property
   @Validate(&quot;required&quot;)
  private String password;]]></script>
-</div></div><p>Now, rebuild the app, refresh the browser, and just hit enter:</p><p>&#160;</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 shape="rect" 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"<br clear="none"> If there is n
 ot message for that key, a second check is made, for <em>fieldId</em>-<em>validatorName</em>-message.</li></ul><p>If that does not match a message, then the built-in default validation message is used.</p><h3 id="FormsandValidation-CustomizingValidationMessagesforBeanEditForm">Customizing Validation Messages for BeanEditForm</h3><p>The <a shape="rect" 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-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 validat
 ion 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">
+</div></div><p>Now, rebuild the app, refresh the browser, and just hit enter:</p><p><img class="confluence-embedded-image confluence-content-image-border image-center" width="500" src="forms-and-validation.data/newapp_com_example.png" data-image-src="/confluence/download/attachments/22872109/newapp_com_example.png?version=3&amp;modificationDate=1428088849224&amp;api=v2"></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&#160;@Validate annotation) is performed again on the server.</p><p>It is also possible to perform extr
 a validation there.</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+<script class="theme: Default; brush: java; gutter: false" type="syntaxhighlighter"><![CDATA[  /**
+     * Do the cross-field validation
+     */
+    void onValidateFromLoginForm() {
+        if (!authenticator.isValid(userName, password)) {
+            // record an error, and thereby prevent Tapestry from emitting a &quot;success&quot; event
+            loginForm.recordError(passwordField, &quot;Invalid user name or password.&quot;);
+        }
+    }
+
+]]></script>
+</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><img class="confluence-embedded-image confluence-content-image-border image-center" width="500" src="forms-and-validation.data/newapp_com_example.png" data-image-src="/confluence/download/attachments/22872109/newapp_com_example.png?v
 ersion=3&amp;modificationDate=1428088849224&amp;api=v2"></p><p>Notice that the cursor is placed directly into the password field.</p>    <div class="aui-message warning shadowed information-macro">
+                            <span class="aui-icon icon-warning">Icon</span>
+                <div class="message-content">
+                            <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>&#160;</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 shape="rect" 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"<br clear="none"> If there is not message for that key, a second check is made, for <em>fieldId</em>-<em>validat
 orName</em>-message.</li></ul><p>If that does not match a message, then the built-in default validation message is used.</p><h3 id="FormsandValidation-CustomizingValidationMessagesforBeanEditForm">Customizing Validation Messages for BeanEditForm</h3><p>The <a shape="rect" 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-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 w
 ith 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">
 <script class="theme: Default; brush: xml; gutter: false" type="syntaxhighlighter"><![CDATA[  &lt;t:textfield t:id=&quot;ssn&quot; validate=&quot;required,regexp&quot;/&gt;
 ]]></script>
 </div></div><p>And your message catalog can contain:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">