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Posted to users@tapestry.apache.org by Amit <am...@fxall.com> on 2005/03/09 21:23:22 UTC
LenientForm - StaleLink Exception
Hi Hanson,
Could you please throw some light on the 'LenientForm' you have implented.
if possible could you cut/paste your part of code implemented thsi way.
Thanks,
Amit
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Re: LenientForm - StaleLink Exception
Posted by Hanson Char <ha...@gmail.com>.
Here you go with the three source files included below, assuming Tapestry 3.0.2:
LenientForm.jwc
LenientForm.java
FormRewindStaleLinkException.java
Now as a drop-in replacement, use @LenientForm instead of @Form. In
one extreme, one can now happily ignore the stale link exception.
Otherwise, one can optionally retrieve the stale link exception in
your page class with something like:
...
import your.own.packagename.FormRewindStaleLinkException;
...
// listener method for the form submit
public void onSubmit(IRequestCycle cycle)
{
FormRewindStaleLinkException ex = getFormRewindStaleLinkException(cycle);
if (ex != null)
// handle it in whatever way you like
...
}
/**
* Returns the FormRewindStaleLinkException detected during a form rewind;
* or null if there was no such exception.
*
* @see {link your.own.packagename.LenientForm}
*/
private FormRewindStaleLinkException
getFormRewindStaleLinkException(IRequestCycle cycle)
{
return (FormRewindStaleLinkException)cycle.getAttribute(
FormRewindStaleLinkException.class.getName());
}
Enjoy,
H
LenientForm.jwc
------------------------
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE component-specification PUBLIC
"-//Apache Software Foundation//Tapestry Specification 3.0//EN"
"http://jakarta.apache.org/tapestry/dtd/Tapestry_3_0.dtd">
<component-specification class="your.own.packagename.LenientForm">
<description>
Used to implement an HTML form.
</description>
<parameter name="method" type="java.lang.String" direction="in">
<description>
The method used by the form when it is submitted, defaults to POST.
</description>
</parameter>
<parameter name="listener"
type="org.apache.tapestry.IActionListener"
required="no"
direction="in">
<description>
Object invoked when the form is submitted, after all form
components have responded
to the submission.
</description>
</parameter>
<parameter name="stateful"
type="boolean"
direction="custom">
<description>
If true (the default), then an active HttpSession is required.
</description>
</parameter>
<parameter name="direct" type="boolean" direction="in">
<description>
If true (the default), then the more efficient direct service is used.
If false, then the action service is used.
</description>
</parameter>
<parameter name="delegate"
type="org.apache.tapestry.valid.IValidationDelegate" direction="in">
<description>
Specifies the delegate to be used by fields to track input errors.
</description>
</parameter>
<reserved-parameter name="action"/>
</component-specification>
LenientForm.java
-------------------------
// Copyright 2004 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package your.own.packagename;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.apache.tapestry.AbstractComponent;
import org.apache.tapestry.ApplicationRuntimeException;
import org.apache.tapestry.IActionListener;
import org.apache.tapestry.IBinding;
import org.apache.tapestry.IDirect;
import org.apache.tapestry.IEngine;
import org.apache.tapestry.IForm;
import org.apache.tapestry.IMarkupWriter;
import org.apache.tapestry.IRequestCycle;
import org.apache.tapestry.RenderRewoundException;
import org.apache.tapestry.StaleLinkException;
import org.apache.tapestry.Tapestry;
import org.apache.tapestry.engine.IEngineService;
import org.apache.tapestry.engine.ILink;
import org.apache.tapestry.form.FormEventType;
import org.apache.tapestry.form.IFormComponent;
import org.apache.tapestry.html.Body;
import org.apache.tapestry.util.IdAllocator;
import org.apache.tapestry.util.StringSplitter;
import org.apache.tapestry.valid.IValidationDelegate;
/**
* Copied from {@link org.apache.tapestry.form.Form} and enhanced such that
* if there was a StaleLinkException detected during rewind,
* instead of throwing up, save the exception as a
* {@link your.own.packagename.FormRewindStaleLinkException}
* in the request attributes, and solier on.
* This allows the application page to have the chance to decide on how
* the exception should be sensibly handled.
*
* Component which contains form element components. Forms use the
* action or direct services to handle the form submission. A Form will wrap
* other components and static HTML, including
* form components such as {@link TextArea}, {@link TextField},
{@link Checkbox}, etc.
*
* [<a href="../../../../../ComponentReference/Form.html">Component
Reference</a>]
*
* <p>When a form is submitted, it continues through the rewind cycle until
* <em>after</em> all of its wrapped elements have renderred. As the form
* component render (in the rewind cycle), they will be updating
* properties of the containing page and notifying thier listeners. Again:
* each form component is responsible not only for rendering HTML (to
present the
* form), but for handling it's share of the form submission.
*
* <p>Only after all that is done will the Form notify its listener.
*
* <p>Starting in release 1.0.2, a Form can use either the direct service or
* the action service. The default is the direct service, even though
* in earlier releases, only the action service was available.
*
* @author Hanson Char
* @author Howard Lewis Ship, David Solis
**/
public abstract class LenientForm extends AbstractComponent implements
IForm, IDirect
{
private static class HiddenValue
{
String _name;
String _value;
String _id;
private HiddenValue(String name, String value)
{
this(name, null, value);
}
private HiddenValue(String name, String id, String value)
{
_name = name;
_id = id;
_value = value;
}
}
private boolean _rewinding;
private boolean _rendering;
private String _name;
/**
* Used when rewinding the form to figure to match allocated ids
(allocated during
* the rewind) against expected ids (allocated in the previous
request cycle, when
* the form was rendered).
*
* @since 3.0
*
**/
private int _allocatedIdIndex;
/**
* The list of allocated ids for form elements within this form. This list
* is constructed when a form renders, and is validated against when the
* form is rewound.
*
* @since 3.0
*
**/
private List _allocatedIds = new ArrayList();
/**
* {@link Map}, keyed on {@link FormEventType}. Values are either a
String (the name
* of a single event), or a {@link List} of Strings.
*
* @since 1.0.2
**/
private Map _events;
private static final int EVENT_MAP_SIZE = 3;
private IdAllocator _elementIdAllocator = new IdAllocator();
private String _encodingType;
private List _hiddenValues;
/**
* Returns the currently active {@link IForm}, or null if no form is
* active. This is a convienience method, the result will be
* null, or an instance of {@link IForm}, but not necessarily a
* <code>Form</code>.
*
**/
public static IForm get(IRequestCycle cycle)
{
return (IForm) cycle.getAttribute(ATTRIBUTE_NAME);
}
/**
* Indicates to any wrapped form components that they should respond
to the form
* submission.
*
* @throws ApplicationRuntimeException if not rendering.
**/
public boolean isRewinding()
{
if (!_rendering)
throw Tapestry.createRenderOnlyPropertyException(this, "rewinding");
return _rewinding;
}
/**
* Returns true if this Form is configured to use the direct
* service.
*
* <p>This is derived from the direct parameter, and defaults
* to true if not bound.
*
* @since 1.0.2
**/
public abstract boolean isDirect();
/**
* Returns true if the stateful parameter is bound to
* a true value. If stateful is not bound, also returns
* the default, true.
*
* @since 1.0.1
**/
public boolean getRequiresSession()
{
return isStateful();
}
/**
* Constructs a unique identifier (within the Form). The identifier
* consists of the component's id, with an index number added to
* ensure uniqueness.
*
* <p>Simply invokes {@link
#getElementId(org.apache.tapestry.form.IFormComponent,
java.lang.String)}
* with the component's id.
*
*
* @since 1.0.2
**/
public String getElementId(IFormComponent component)
{
return getElementId(component, component.getId());
}
/**
* Constructs a unique identifier from the base id. If possible, the
* id is used as-is. Otherwise, a unique identifier is appended
* to the id.
*
* <p>This method is provided simply so that some components
* ({@link ImageSubmit}) have more specific control over
* their names.
*
* @since 1.0.3
*
**/
public String getElementId(IFormComponent component, String baseId)
{
String result = _elementIdAllocator.allocateId(baseId);
if (_rewinding)
{
if (_allocatedIdIndex >= _allocatedIds.size())
{
throw new StaleLinkException(
Tapestry.format(
"Form.too-many-ids",
getExtendedId(),
Integer.toString(_allocatedIds.size()),
component.getExtendedId()),
this);
}
String expected = (String) _allocatedIds.get(_allocatedIdIndex);
if (!result.equals(expected))
throw new StaleLinkException(
Tapestry.format(
"Form.id-mismatch",
new Object[] {
getExtendedId(),
Integer.toString(_allocatedIdIndex + 1),
expected,
result,
component.getExtendedId()}),
this);
}
else
{
_allocatedIds.add(result);
}
_allocatedIdIndex++;
component.setName(result);
return result;
}
/**
* Returns the name generated for the form. This is used to faciliate
* components that write JavaScript and need to access the form or
* its contents.
*
* <p>This value is generated when the form renders, and is not cleared.
* If the Form is inside a {@link org.apache.tapestry.components.Foreach},
* this will be the most recently
* generated name for the Form.
*
* <p>This property is exposed so that sophisticated applications can write
* JavaScript handlers for the form and components within the form.
*
* @see AbstractFormComponent#getName()
*
**/
public String getName()
{
return _name;
}
/** @since 3.0 **/
protected void prepareForRender(IRequestCycle cycle)
{
super.prepareForRender(cycle);
if (cycle.getAttribute(ATTRIBUTE_NAME) != null)
throw new ApplicationRuntimeException(
Tapestry.getMessage("Form.forms-may-not-nest"),
this,
null,
null);
cycle.setAttribute(ATTRIBUTE_NAME, this);
}
protected void cleanupAfterRender(IRequestCycle cycle)
{
_rendering = false;
_allocatedIdIndex = 0;
_allocatedIds.clear();
_events = null;
_elementIdAllocator.clear();
if (_hiddenValues != null)
_hiddenValues.clear();
cycle.removeAttribute(ATTRIBUTE_NAME);
_encodingType = null;
IValidationDelegate delegate = getDelegate();
if (delegate != null)
delegate.setFormComponent(null);
super.cleanupAfterRender(cycle);
}
protected void writeAttributes(IMarkupWriter writer, ILink link)
{
String method = getMethod();
writer.begin(getTag());
writer.attribute("method", (method == null) ? "post" : method);
writer.attribute("name", _name);
writer.attribute("action", link.getURL(null, false));
if (_encodingType != null)
writer.attribute("enctype", _encodingType);
}
protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle)
{
String actionId = cycle.getNextActionId();
_name = getDisplayName() + actionId;
boolean renderForm = !cycle.isRewinding();
boolean rewound = cycle.isRewound(this);
_rewinding = rewound;
_allocatedIdIndex = 0;
_rendering = true;
if (rewound)
{
String storedIdList = cycle.getRequestContext().getParameter(_name);
reconstructAllocatedIds(storedIdList);
}
ILink link = getLink(cycle, actionId);
// When rendering, use a nested writer so that an embedded Upload
// component can force the encoding type.
IMarkupWriter nested = writer.getNestedWriter();
renderBody(nested, cycle);
if (renderForm)
{
writeAttributes(writer, link);
renderInformalParameters(writer, cycle);
writer.println();
}
// Write the hidden's, or at least, reserve the query parameters
// required by the Gesture.
writeLinkParameters(writer, link, !renderForm);
if (renderForm)
{
// What's this for? It's part of checking for stale links.
// We record the list of allocated ids.
// On rewind, we check that the stored list against which
// ids were allocated. If the persistent state of the page or
// application changed between render (previous request cycle)
// and rewind (current request cycle), then the list
// of ids will change as well.
writeHiddenField(writer, _name, buildAllocatedIdList());
writeHiddenValues(writer);
nested.close();
writer.end(getTag());
// Write out event handlers collected during the rendering.
emitEventHandlers(writer, cycle);
}
if (rewound)
{
int expected = _allocatedIds.size();
// The other case, _allocatedIdIndex > expected, is
// checked for inside getElementId(). Remember that
// _allocatedIdIndex is incremented after allocating.
if (_allocatedIdIndex < expected)
{
String nextExpectedId = (String) _allocatedIds.get(_allocatedIdIndex);
// a0093: change from throwing an exception
// to recording it as a request attribute.
FormRewindStaleLinkException ex = new FormRewindStaleLinkException(
Tapestry.format(
"Form.too-few-ids",
getExtendedId(),
Integer.toString(expected - _allocatedIdIndex),
nextExpectedId),
this);
cycle.setAttribute(FormRewindStaleLinkException.class.getName(), ex);
}
IActionListener listener = getListener();
if (listener != null)
listener.actionTriggered(this, cycle);
// Abort the rewind render.
throw new RenderRewoundException(this);
}
}
/**
* Adds an additional event handler.
*
* @since 1.0.2
*
**/
public void addEventHandler(FormEventType type, String functionName)
{
if (_events == null)
_events = new HashMap(EVENT_MAP_SIZE);
Object value = _events.get(type);
// The value can either be a String, or a List of String. Since
// it is rare for there to be more than one event handling function,
// we start with just a String.
if (value == null)
{
_events.put(type, functionName);
return;
}
// The second function added converts it to a List.
if (value instanceof String)
{
List list = new ArrayList();
list.add(value);
list.add(functionName);
_events.put(type, list);
return;
}
// The third and subsequent function just
// adds to the List.
List list = (List) value;
list.add(functionName);
}
protected void emitEventHandlers(IMarkupWriter writer, IRequestCycle cycle)
{
if (_events == null || _events.isEmpty())
return;
Body body = Body.get(cycle);
if (body == null)
throw new ApplicationRuntimeException(
Tapestry.getMessage("Form.needs-body-for-event-handlers"),
this,
null,
null);
StringBuffer buffer = new StringBuffer();
Iterator i = _events.entrySet().iterator();
while (i.hasNext())
{
Map.Entry entry = (Map.Entry) i.next();
FormEventType type = (FormEventType) entry.getKey();
Object value = entry.getValue();
buffer.append("document.");
buffer.append(_name);
buffer.append(".");
buffer.append(type.getPropertyName());
buffer.append(" = ");
// The typical case; one event one event handler. Easy enough.
if (value instanceof String)
{
buffer.append(value.toString());
buffer.append(";");
}
else
{
// Build a composite function in-place
buffer.append("function ()\n{\n");
boolean combineWithAnd = type.getCombineUsingAnd();
List l = (List) value;
int count = l.size();
for (int j = 0; j < count; j++)
{
String functionName = (String) l.get(j);
if (j > 0)
{
if (combineWithAnd)
buffer.append(" &&");
else
buffer.append(";");
}
buffer.append("\n ");
if (combineWithAnd)
{
if (j == 0)
buffer.append("return ");
else
buffer.append(" ");
}
buffer.append(functionName);
buffer.append("()");
}
buffer.append(";\n}");
}
buffer.append("\n\n");
}
body.addInitializationScript(buffer.toString());
}
/**
* Simply invokes {@link #render(IMarkupWriter, IRequestCycle)}.
*
* @since 1.0.2
*
**/
public void rewind(IMarkupWriter writer, IRequestCycle cycle)
{
render(writer, cycle);
}
/**
* Method invoked by the direct service.
*
* @since 1.0.2
*
**/
public void trigger(IRequestCycle cycle)
{
Object[] parameters = cycle.getServiceParameters();
cycle.rewindForm(this, (String) parameters[0]);
}
/**
* Builds the EngineServiceLink for the form, using either the direct or
* action service.
*
* @since 1.0.3
*
**/
private ILink getLink(IRequestCycle cycle, String actionId)
{
String serviceName = null;
if (isDirect())
serviceName = Tapestry.DIRECT_SERVICE;
else
serviceName = Tapestry.ACTION_SERVICE;
IEngine engine = cycle.getEngine();
IEngineService service = engine.getService(serviceName);
// A single service parameter is used to store the actionId.
return service.getLink(cycle, this, new String[] { actionId });
}
private void writeLinkParameters(IMarkupWriter writer, ILink link,
boolean reserveOnly)
{
String[] names = link.getParameterNames();
int count = Tapestry.size(names);
for (int i = 0; i < count; i++)
{
String name = names[i];
// Reserve the name.
_elementIdAllocator.allocateId(name);
if (!reserveOnly)
writeHiddenFieldsForParameter(writer, link, name);
}
}
/**
* @since 3.0
*
**/
protected void writeHiddenField(IMarkupWriter writer, String name,
String value)
{
writeHiddenField(writer, name, null, value);
}
protected void writeHiddenField(IMarkupWriter writer, String name,
String id, String value)
{
writer.beginEmpty("input");
writer.attribute("type", "hidden");
writer.attribute("name", name);
if(id != null && id.length() != 0)
writer.attribute("id", id);
writer.attribute("value", value);
writer.println();
}
/**
* @since 2.2
*
**/
private void writeHiddenFieldsForParameter(
IMarkupWriter writer,
ILink link,
String parameterName)
{
String[] values = link.getParameterValues(parameterName);
for (int i = 0; i < values.length; i++)
{
writeHiddenField(writer, parameterName, values[i]);
}
}
/**
* Converts the allocateIds property into a string, a
comma-separated list of ids.
* This is included as a hidden field in the form and is used to identify
* discrepencies when the form is submitted.
*
* @since 3.0
*
**/
protected String buildAllocatedIdList()
{
StringBuffer buffer = new StringBuffer();
int count = _allocatedIds.size();
for (int i = 0; i < count; i++)
{
if (i > 0)
buffer.append(',');
buffer.append(_allocatedIds.get(i));
}
return buffer.toString();
}
/**
* Converts a string passed as a parameter (and containing a comma
* separated list of ids) back into the allocateIds property.
*
* @see #buildAllocatedIdList()
*
* @since 3.0
*
**/
protected void reconstructAllocatedIds(String storedIdList)
{
if (Tapestry.isBlank(storedIdList))
return;
StringSplitter splitter = new StringSplitter(',');
String[] ids = splitter.splitToArray(storedIdList);
for (int i = 0; i < ids.length; i++)
_allocatedIds.add(ids[i]);
}
public abstract IValidationDelegate getDelegate();
public abstract void setDelegate(IValidationDelegate delegate);
public abstract void setDirect(boolean direct);
public abstract IActionListener getListener();
public abstract String getMethod();
/**
* Invoked when not rendering, so it uses the stateful binding.
* If not bound, returns true.
*
**/
public boolean isStateful()
{
IBinding statefulBinding = getStatefulBinding();
if (statefulBinding == null)
return true;
return statefulBinding.getBoolean();
}
public abstract IBinding getStatefulBinding();
protected void finishLoad()
{
setDirect(true);
}
public void setEncodingType(String encodingType)
{
if (_encodingType != null && !_encodingType.equals(encodingType))
throw new ApplicationRuntimeException(
Tapestry.format(
"Form.encoding-type-contention",
getExtendedId(),
_encodingType,
encodingType),
this,
null,
null);
_encodingType = encodingType;
}
/**
* Returns the tag of the form.
*
* @since 3.0
*
**/
protected String getTag()
{
return "form";
}
/**
* Returns the name of the element.
*
*
* @since 3.0
**/
protected String getDisplayName()
{
return "Form";
}
/** @since 3.0 */
public void addHiddenValue(String name, String value)
{
if (_hiddenValues == null)
_hiddenValues = new ArrayList();
_hiddenValues.add(new HiddenValue(name, value));
}
/** @since 3.0 */
public void addHiddenValue(String name, String id, String value)
{
if (_hiddenValues == null)
_hiddenValues = new ArrayList();
_hiddenValues.add(new HiddenValue(name, id, value));
}
/**
* Writes hidden values accumulated during the render
* (by components invoking {@link #addHiddenValue(String, String)}.
*
* @since 3.0
*/
protected void writeHiddenValues(IMarkupWriter writer)
{
int count = Tapestry.size(_hiddenValues);
for (int i = 0; i < count; i++)
{
HiddenValue hv = (HiddenValue) _hiddenValues.get(i);
writeHiddenField(writer, hv._name, hv._id, hv._value);
}
}
}
FormRewindStaleLinkException.java
-----------------------------------------------------
package your.own.packagename;
import org.apache.tapestry.IComponent;
import org.apache.tapestry.IPage;
import org.apache.tapestry.StaleLinkException;
/**
* A {@link org.apache.tapestry.StaleLinkException} thrown durinig a
form rewind.
*
* Used in conjunction with {@link your.own.packagename.LenientForm}
*
* @author Hanson Char
*/
public class FormRewindStaleLinkException extends StaleLinkException {
public FormRewindStaleLinkException()
{
super();
}
/**
* Constructor used when the action id is found, but the target id path
* did not match the actual id path.
*
**/
public FormRewindStaleLinkException(IComponent component, String
targetActionId, String targetIdPath)
{
super(component, targetActionId, targetIdPath);
}
/**
* Constructor used when the target action id is not found.
*
**/
public FormRewindStaleLinkException(IPage page, String
targetActionId, String targetIdPath)
{
super(page, targetActionId, targetIdPath);
}
public FormRewindStaleLinkException(String message, IComponent component)
{
super(message, component);
}
}
On Wed, 9 Mar 2005 20:23:22 +0000 (UTC), Amit <am...@fxall.com> wrote:
> Hi Hanson,
>
> Could you please throw some light on the 'LenientForm' you have implented.
>
> if possible could you cut/paste your part of code implemented thsi way.
>
> Thanks,
> Amit
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: tapestry-user-unsubscribe@jakarta.apache.org
> For additional commands, e-mail: tapestry-user-help@jakarta.apache.org
>
>
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