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| <article class="container"> |
| <section class="col-md-12"> |
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| |
| <h1 id="alt-syntax">Alt Syntax</h1> |
| |
| <blockquote> |
| <p>Note: As from Struts 2.6 option to disable the AltSyntax has been removed and now using %{…} is the only way |
| to create an expression as stated below.</p> |
| </blockquote> |
| |
| <p>The <em>altSyntax</em> is an option that can be defined in <code class="highlighter-rouge">struts.xml</code>. By default it is set to true and it is <strong>strongly</strong> |
| recommend you do not change that unless you are upgrading from WebWork 2.1.7 or previous versions.</p> |
| |
| <blockquote> |
| <p>You can also turn on the altSyntax on a per-page basis by using the <em>set</em> tag. Simply set the name <em>useAltSyntax</em><br /> |
| to the value <em>true</em> . From this point on, all tags will use the altSyntax for the rest of the request.</p> |
| </blockquote> |
| |
| <p>The altSyntax changes the behavior of how tags are interpreted. Instead of evaluating each tag parameter against |
| the value stack and needing single quotes to mark string literals, only marked expressions are evaluated.</p> |
| |
| <p>Example:</p> |
| |
| <p>the following code uses the <a href="tag-syntax.html">Tag Syntax</a>:</p> |
| |
| <pre><code class="language-jsp"><s:iterator value="cart.items"> |
| ... |
| <s:textfield label="'Cart item No.' + #rowstatus.index + ' note'" |
| name="'cart.items[' + #rowstatus.index + '].note'" |
| value="note" /> |
| </s:iterator> |
| </code></pre> |
| |
| <p>this is somewhat counter intuitive to normal HTML tag behaviour, and you get loads of single quotes. Now the same example |
| in altSyntax:</p> |
| |
| <pre><code class="language-jsp"><s:iterator value="cart.items"> |
| ... |
| <s:textfield label="Cart item No. %{#rowstatus.index} note" |
| name="cart.items[%{#rowstatus.index}].note" |
| value="%{note}" /> |
| </s:iterator> |
| </code></pre> |
| |
| <p>Only expressions enclosed with <code class="highlighter-rouge">%{}</code> are evaluated. The code is shorter and clearer, very similar to JSTL EL usage. |
| Quoting problems, eg. with javascript function calls, are avoided.</p> |
| |
| <p>In order to fully understand why this option exists and what the differences are, it is best to get a bit of history |
| about WebWork.</p> |
| |
| <blockquote> |
| <p>If you are <em>not</em> upgrading from WebWork 2.1.7 or previous versions and you don’t care about the history of WebWork’s |
| evolution, you can skip this section. See the <a href="tag-syntax.html">Tag Syntax</a> section for more information |
| on the standard tag syntax support</p> |
| </blockquote> |
| |
| <h2 id="history">History</h2> |
| |
| <p>In WebWork 2.1.4, the altSyntax option was introduced. The book, WebWork in Action, while based around WebWork 2.1.7, |
| was entirely written with the assumption that the altSyntax was enabled. As of WebWork 2.2, the altSyntax is turned |
| on by default and eventually the old syntax will no longer be supported and will be removed from the code.</p> |
| |
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