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| <h1 class="content-header header-section1" id="dgui_template_directives" itemprop="headline">Directives</h1> |
| </div></div><a name="term.designer.directive"></a><p>You use FTL tags to call <strong>directives</strong>. In the example you have called the |
| <code class="inline-code">list</code> directive. Syntactically you have done it with |
| two tags: <code class="inline-code"><#list animals as being></code> and |
| <code class="inline-code"></#list></code>.</p><p>There are two kind of FTL tags:</p><ul> |
| <li> |
| <p>Start-tag: |
| <code class="inline-code"><#<em class="code-color">directivename</em> |
| <em class="code-color">parameters</em>></code></p> |
| </li> |
| |
| <li> |
| <p>End-tag: |
| <code class="inline-code"></#<em class="code-color">directivename</em>></code></p> |
| </li> |
| </ul><p>This is similar to HTML or XML syntax, except that the tag name |
| starts with <code class="inline-code">#</code>. If the directive doesn't have nested |
| content (content between the start-tag and the end-tag), you must use |
| the start-tag with no end-tag. For example you write <code class="inline-code"><#if |
| <em class="code-color">something</em>><em class="code-color">...</em></#if></code>, |
| but just <code class="inline-code"><#include |
| <em class="code-color">something</em>></code> as FreeMarker knows |
| that the <code class="inline-code">include</code> directive can't have nested |
| content.</p><p>The format of the |
| <code class="inline-code"><em class="code-color">parameters</em></code> depends on |
| the |
| <code class="inline-code"><em class="code-color">directivename</em></code>.</p><p>In fact there are two types of directives: <a href="gloss.html#gloss.predefinedDirective">predefined directives</a> and |
| <a href="gloss.html#gloss.userDefinedDirective">user-defined |
| directives</a>. For user-defined directives you use |
| <code class="inline-code">@</code> instead of <code class="inline-code">#</code>, for example |
| <code class="inline-code"><@mydirective |
| <em class="code-color">parameters</em>><em class="code-color">...</em></@mydirective></code>. |
| Further difference is that if the directive has no nested content, you |
| must use a tag like <code class="inline-code"><@mydirective |
| <em class="code-color">parameters</em> /></code>, similarly as in |
| XML (e.g. <code class="inline-code"><img <em class="code-color">...</em> |
| /></code>). But user-defined directives is an advanced topic |
| that will be discussed <a href="dgui_misc_userdefdir.html">later</a>.</p><p>FTL tags, like HTML tags, must be properly nested. So the code |
| below is wrong, as the <code class="inline-code">if</code> directive is both inside |
| and outside of the nested content of the <code class="inline-code">list</code> |
| directive:</p> |
| |
| <div class="code-wrapper"><pre class="code-block code-template"><ul> |
| <strong><#list animals as being></strong> |
| <li>${being.name} for ${being.price} Euros |
| <strong><#if user == "Big Joe"></strong> |
| (except for you) |
| <strong></#list></strong> <#-- WRONG! The "if" has to be closed first. --> |
| <strong></#if></strong> |
| </ul></pre></div><p>Note that FreeMarker doesn't care about the nesting of HTML |
| tags, only about the nesting of FTL tags. It just sees HTML as flat |
| text, it doesn't interpret it in any way.</p><p>If you try to use a non-existing directive (e.g., you mistype |
| the directive name), FreeMarker will decline to use the template and |
| produce an error message.</p><p>FreeMarker ignores superfluous <a href="gloss.html#gloss.whiteSpace">white-space</a> inside FTL tags. So you |
| can write this:</p> |
| |
| <div class="code-wrapper"><pre class="code-block code-template"><span class="marked-text"><span class="marked-ftl-tag"><#list<em><span class="marked-invisible-text">[BR]</span></em> |
| animals as<em><span class="marked-invisible-text">[BR]</span></em> |
| being<em><span class="marked-invisible-text">[BR]</span></em> |
| ></span><em><span class="marked-invisible-text">[BR]</span></em> |
| <span class="marked-interpolation">${being.name}</span> for <span class="marked-interpolation">${being.price}</span> Euros<em><span class="marked-invisible-text">[BR]</span></em> |
| <span class="marked-ftl-tag"></#list ></span></span></pre></div><p>You may not, however, insert white-space between the |
| <code class="inline-code"><</code> or <code class="inline-code"></</code> and the directive |
| name.</p><p>The complete list and description of all directives can be found |
| in the <a href="ref_directives.html">Reference/Directive Reference</a> (but I recommend that you |
| look at the chapter about expressions first).</p> <div class="callout note"> |
| <strong class="callout-label">Note:</strong> |
| |
| <p>FreeMarker can be configured to use <code class="inline-code">[</code> and |
| <code class="inline-code">]</code> instead of <code class="inline-code"><</code> and |
| <code class="inline-code">></code> in the FTL tags and FTL comments, like |
| <code class="inline-code">[#if user == "Big |
| Joe"]<em class="code-color">...</em>[/#if]</code>. For more |
| information read: <a href="dgui_misc_alternativesyntax.html">Miscellaneous/Alternative (square bracket) syntax</a>.</p> |
| </div> |
| <div class="callout note"> |
| <strong class="callout-label">Note:</strong> |
| |
| <p>FreeMarker can be configured so that it understands predefined |
| directives without <code class="inline-code">#</code> (like <code class="inline-code"><if user |
| == "Big |
| Joe"><em class="code-color">...</em></if></code>). |
| However we don't recommend the usage of this mode. For more |
| information read: <a href="ref_depr_oldsyntax.html">Reference/Deprecated FTL constructs/Old FTL syntax</a></p> |
| </div> |
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