webwork / docs / tags / IteratorComponent.html

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<title>&lt;ww:iterator /&gt;</title>
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<h1>Tag Name: &lt;ww:iterator /&gt;</h1>

<h2>Description</h2>
<p>

Iterate over a iterable value

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<p>
<!-- START SNIPPET: javadoc --> <p>Iterator will iterate over a value. An iterable value can be either of: java.util.Collection, java.util.Iterator, java.util.Enumeration, java.util.Map, array.</p> <p/> <!-- END SNIPPET: javadoc --> <!-- START SNIPPET: params --> <ul> <li>status (String) - if specified, an instanceof IteratorStatus will be pushed into stack upon each iteration</li> <li>value (Object) - the source to iterate over, must be iteratable, else an the object itself will be put into a newly created List (see MakeIterator#convert(Object)</li> <li>id (String) - if specified the current iteration object will be place with this id in webwork stack's context scope</li> </ul> <!-- END SNIPPET: params --> <!-- START SNIPPET: example1description --> <p>The following example retrieves the value of the getDays() method of the current object on the value stack and uses it to iterate over. The &lt;ww:property/&gt; tag prints out the current value of the iterator.</p> <!-- END SNIPPET: example1description --> <pre> <!-- START SNIPPET: example1code --> &lt;ww:iterator value="days"&gt; &lt;p&gt;day is: &lt;ww:property/&gt;&lt;/p&gt; &lt;/ww:iterator&gt; <!-- END SNIPPET: example1code --> </pre> <!-- START SNIPPET: example2description --> <p>The following example uses a {@link Bean} tag and places it into the ActionContext. The iterator tag will retrieve that object from the ActionContext and then calls its getDays() method as above. The status attribute is also used to create a {@link IteratorStatus} object, which in this example, its odd() method is used to alternate row colours:</p> <!-- END SNIPPET: example2description --> <pre> <!-- START SNIPPET: example2code --> &lt;ww:bean name="com.opensymphony.webwork.example.IteratorExample" id="it"&gt; &lt;ww:param name="day" value="'foo'"/&gt; &lt;ww:param name="day" value="'bar'"/&gt; &lt;/ww:bean&gt; <p/> &lt;table border="0" cellspacing="0" cellpadding="1"&gt; &lt;tr&gt; &lt;th&gt;Days of the week&lt;/th&gt; &lt;/tr&gt; <p/> &lt;ww:iterator value="#it.days" status="rowstatus"&gt; &lt;tr&gt; &lt;ww:if test="#rowstatus.odd == true"&gt; &lt;td style="background: grey"&gt;&lt;ww:property/&gt;&lt;/td&gt; &lt;/ww:if&gt; &lt;ww:else&gt; &lt;td&gt;&lt;ww:property/&gt;&lt;/td&gt; &lt;/ww:else&gt; &lt;/tr&gt; &lt;/ww:iterator&gt; &lt;/table&gt; <!-- END SNIPPET: example2code --> </pre> <!--START SNIPPET: example3description --> <p> The next example will further demonstrate the use of the status attribute, using a DAO obtained from the action class through OGNL, iterating over groups and their users (in a security context). The last() method indicates if the current object is the last available in the iteration, and if not, we need to seperate the users using a comma: </p> <!-- END SNIPPET: example3description --> <pre> <!-- START SNIPPET: example3code --> &lt;webwork:iterator value="groupDao.groups" status="groupStatus"&gt; &lt;tr class="&lt;webwork:if test="#groupStatus.odd == true "&gt;odd&lt;/webwork:if&gt;&lt;webwork:else&gt;even&lt;/webwork:else&gt;"&gt; &lt;td&gt;&lt;webwork:property value="name" /&gt;&lt;/td&gt; &lt;td&gt;&lt;webwork:property value="description" /&gt;&lt;/td&gt; &lt;td&gt; &lt;webwork:iterator value="users" status="userStatus"&gt; &lt;webwork:property value="fullName" /&gt;&lt;webwork:if test="!#userStatus.last"&gt;,&lt;/webwork:if&gt; &lt;/webwork:iterator&gt; &lt;/td&gt; &lt;/tr&gt; &lt;/webwork:iterator&gt; <!-- END SNIPPET: example3code --> </pre> <p> <!-- START SNIPPET: example4description --> </p> The next example iterates over a an action collection and passes every iterator value to another action. The trick here lies in the use of the '[0]' operator. It takes the current iterator value and passes it on to the edit action. Using the '[0]' operator has the same effect as using &gt;ww:property /&gt;. (The latter, however, does not work from inside the param tag). </p> <!-- END SNIPPET: example4description --> <pre> <!-- START SNIPPET: example4code --> &lt;ww:action name="entries" id="entries"/&gt; &lt;ww:iterator value="#entries.entries" &gt; &lt;ww:property value="name" /&gt; &lt;ww:property /&gt; &lt;ww:push value="..."&gt; &lt;ww:action name="edit" id="edit" &gt; &lt;ww:param name="entry" value="[0]" /&gt; &lt;/ww:action&gt; &lt;/push&gt; &lt;/ww:iterator&gt; <!-- END SNIPPET: example4code --> </pre>
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<h2>Attributes</h2>
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<!-- START SNIPPET: tagattributes -->
<table width="100%">
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<th align="left" valign="top"><h4>Name</h4></th>
<th align="left" valign="top"><h4>Required</h4></th>
<th align="left" valign="top"><h4>Default</h4></th>
<th align="left" valign="top"><h4>Type</h4></th>
<th align="left" valign="top"><h4>Description</h4></th>

</tr>

<tr>
<!-- Attribute name -->
<td align="left" valign="top">status</td>

<!-- Required -->
<td align="left" valign="top">false</td>

<!-- Default -->
<td align="left" valign="top">false</td>

<!-- Type -->
<td align="left" valign="top">Boolean</td>

<!-- Description -->
<td align="left" valign="top">if specified, an instanceof IteratorStatus will be pushed into stack upon each iteration</td>

</tr>

<tr>
<!-- Attribute name -->
<td align="left" valign="top">value</td>

<!-- Required -->
<td align="left" valign="top">false</td>

<!-- Default -->
<td align="left" valign="top">&nbsp;</td>

<!-- Type -->
<td align="left" valign="top">Object/String</td>

<!-- Description -->
<td align="left" valign="top">the iteratable source to iterate over, else an the object itself will be put into a newly created List</td>

</tr>

<tr>
<!-- Attribute name -->
<td align="left" valign="top">id</td>

<!-- Required -->
<td align="left" valign="top">false</td>

<!-- Default -->
<td align="left" valign="top">&nbsp;</td>

<!-- Type -->
<td align="left" valign="top">Object/String</td>

<!-- Description -->
<td align="left" valign="top">id for referencing element. For UI and form tags it will be used as HTML id attribute</td>

</tr>

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<!-- END SNIPPET: tagattributes -->

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