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     <a class="edit-on-gh" href="https://github.com/apache/struts-site/edit/master/source/core-developers/prepare-interceptor.md" title="Edit this page on GitHub">Edit on GitHub</a>

     <a href="interceptors.html" title="back to Interceptors"><< back to Interceptors</a>

     <h1 id="prepare-interceptor">Prepare Interceptor</h1>

 <p>This interceptor calls <code class="highlighter-rouge">prepare()</code> on actions which implement <code class="highlighter-rouge">Preparable</code>. This interceptor is very useful for any
 situation where you need to ensure some logic runs before the actual execute method runs.</p>

 <p>A typical use of this is to run some logic to load an object from the database so that when parameters are set they can
 be set on this object. For example, suppose you have a User object with two properties: <code class="highlighter-rouge">id</code> and <code class="highlighter-rouge">name</code>. Provided that
 the params interceptor is called twice (once before and once after this interceptor), you can load the User object using
 the <code class="highlighter-rouge">id</code> property and then when the second params interceptor is called the parameter <code class="highlighter-rouge">user.name</code> will be set, as desired,
 on the actual object loaded from the database. See the example for more info.</p>

 <blockquote>
   <p>Note: Since XWork 2.0.2, this interceptor extends <code class="highlighter-rouge">MethodFilterInterceptor</code>, therefore being able to deal with
 <code class="highlighter-rouge">excludeMethods</code> / <code class="highlighter-rouge">includeMethods</code> parameters. See <a href="default-workflow-interceptor.html">Workflow Interceptor</a>
 for documentation and examples on how to use this feature.</p>
 </blockquote>

 <blockquote>
   <p>Update: Added logic to execute a <code class="highlighter-rouge">prepare&lt;MethodName&gt;</code> and conditionally the a general <code class="highlighter-rouge">prepare()</code> Method, depending
 on the <code class="highlighter-rouge">alwaysInvokePrepare</code> parameter/property which is by default <code class="highlighter-rouge">true</code>. This allows us to run some logic based
 on the method name we specify in the <code class="highlighter-rouge">com.opensymphony.xwork2.ActionProxy</code>. For example, you can specify a <code class="highlighter-rouge">prepareInput()</code>
 method that will be run before the invocation of the input method.</p>
 </blockquote>

 <p>In <code class="highlighter-rouge">PrepareInterceptor</code> applies only when action implements <code class="highlighter-rouge">Preparable</code></p>
 <ol>
   <li>if the action class have <code class="highlighter-rouge">prepare&lt;MethodName&gt;()</code>, it will be invoked</li>
   <li>else if the action class have <code class="highlighter-rouge">prepareDo&lt;MethodName&gt;()</code>, it will be invoked</li>
   <li>no matter if 1] or 2] is performed, if <code class="highlighter-rouge">alwaysInvokePrepare</code> property of the interceptor is <code class="highlighter-rouge">true</code> (which is by
    default <code class="highlighter-rouge">true</code>), <code class="highlighter-rouge">prepare()</code> will be invoked.</li>
 </ol>

 <h2 id="parameters">Parameters</h2>

 <ul>
   <li><code class="highlighter-rouge">alwaysInvokePrepare</code> - Default to true. If true, prepare will always be invoked, otherwise it will not.</li>
 </ul>

 <h2 id="extending-the-interceptor">Extending the Interceptor</h2>

 <p>There are no known extension points to this interceptor.</p>

 <h2 id="examples">Examples</h2>

 <div class="language-xml highlighter-rouge"><div class="highlight"><pre class="highlight"><code> <span class="c">&lt;!-- Calls the params interceptor twice, allowing you to
        pre-load data for the second time parameters are set --&gt;</span>
   <span class="nt">&lt;action</span> <span class="na">name=</span><span class="s">"someAction"</span> <span class="na">class=</span><span class="s">"com.examples.SomeAction"</span><span class="nt">&gt;</span>
       <span class="nt">&lt;interceptor-ref</span> <span class="na">name=</span><span class="s">"params"</span><span class="nt">/&gt;</span>
       <span class="nt">&lt;interceptor-ref</span> <span class="na">name=</span><span class="s">"prepare"</span><span class="nt">/&gt;</span>
       <span class="nt">&lt;interceptor-ref</span> <span class="na">name=</span><span class="s">"basicStack"</span><span class="nt">/&gt;</span>
       <span class="nt">&lt;result</span> <span class="na">name=</span><span class="s">"success"</span><span class="nt">&gt;</span>good_result.ftl<span class="nt">&lt;/result&gt;</span>
   <span class="nt">&lt;/action&gt;</span>
 </code></pre></div></div>

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	<a class="edit-on-gh" href="https://github.com/apache/struts-site/edit/master/source/core-developers/prepare-interceptor.md" title="Edit this page on GitHub">Edit on GitHub</a>

	<a href="interceptors.html" title="back to Interceptors"><< back to Interceptors</a>

	<h1 id="prepare-interceptor">Prepare Interceptor</h1>

	<p>This interceptor calls <code class="highlighter-rouge">prepare()</code> on actions which implement <code class="highlighter-rouge">Preparable</code>. This interceptor is very useful for any
	situation where you need to ensure some logic runs before the actual execute method runs.</p>

	<p>A typical use of this is to run some logic to load an object from the database so that when parameters are set they can
	be set on this object. For example, suppose you have a User object with two properties: <code class="highlighter-rouge">id</code> and <code class="highlighter-rouge">name</code>. Provided that
	the params interceptor is called twice (once before and once after this interceptor), you can load the User object using
	the <code class="highlighter-rouge">id</code> property and then when the second params interceptor is called the parameter <code class="highlighter-rouge">user.name</code> will be set, as desired,
	on the actual object loaded from the database. See the example for more info.</p>

	<blockquote>
	<p>Note: Since XWork 2.0.2, this interceptor extends <code class="highlighter-rouge">MethodFilterInterceptor</code>, therefore being able to deal with
	<code class="highlighter-rouge">excludeMethods</code> / <code class="highlighter-rouge">includeMethods</code> parameters. See <a href="default-workflow-interceptor.html">Workflow Interceptor</a>
	for documentation and examples on how to use this feature.</p>
	</blockquote>

	<blockquote>
	<p>Update: Added logic to execute a <code class="highlighter-rouge">prepare<MethodName></code> and conditionally the a general <code class="highlighter-rouge">prepare()</code> Method, depending
	on the <code class="highlighter-rouge">alwaysInvokePrepare</code> parameter/property which is by default <code class="highlighter-rouge">true</code>. This allows us to run some logic based
	on the method name we specify in the <code class="highlighter-rouge">com.opensymphony.xwork2.ActionProxy</code>. For example, you can specify a <code class="highlighter-rouge">prepareInput()</code>
	method that will be run before the invocation of the input method.</p>
	</blockquote>

	<p>In <code class="highlighter-rouge">PrepareInterceptor</code> applies only when action implements <code class="highlighter-rouge">Preparable</code></p>
	<ol>
	<li>if the action class have <code class="highlighter-rouge">prepare<MethodName>()</code>, it will be invoked</li>
	<li>else if the action class have <code class="highlighter-rouge">prepareDo<MethodName>()</code>, it will be invoked</li>
	<li>no matter if 1] or 2] is performed, if <code class="highlighter-rouge">alwaysInvokePrepare</code> property of the interceptor is <code class="highlighter-rouge">true</code> (which is by
	default <code class="highlighter-rouge">true</code>), <code class="highlighter-rouge">prepare()</code> will be invoked.</li>
	</ol>

	<h2 id="parameters">Parameters</h2>

	<ul>
	<li><code class="highlighter-rouge">alwaysInvokePrepare</code> - Default to true. If true, prepare will always be invoked, otherwise it will not.</li>
	</ul>

	<h2 id="extending-the-interceptor">Extending the Interceptor</h2>

	<p>There are no known extension points to this interceptor.</p>

	<h2 id="examples">Examples</h2>

	<div class="language-xml highlighter-rouge"><div class="highlight"><pre class="highlight"><code> <span class="c"><!-- Calls the params interceptor twice, allowing you to
	pre-load data for the second time parameters are set --></span>
	<span class="nt"><action</span> <span class="na">name=</span><span class="s">"someAction"</span> <span class="na">class=</span><span class="s">"com.examples.SomeAction"</span><span class="nt">></span>
	<span class="nt"><interceptor-ref</span> <span class="na">name=</span><span class="s">"params"</span><span class="nt">/></span>
	<span class="nt"><interceptor-ref</span> <span class="na">name=</span><span class="s">"prepare"</span><span class="nt">/></span>
	<span class="nt"><interceptor-ref</span> <span class="na">name=</span><span class="s">"basicStack"</span><span class="nt">/></span>
	<span class="nt"><result</span> <span class="na">name=</span><span class="s">"success"</span><span class="nt">></span>good_result.ftl<span class="nt"></result></span>
	<span class="nt"></action></span>
	</code></pre></div></div>

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