| <!doctype html> |
| <!-- Generated by FreeMarker/Docgen from DocBook --> |
| <html lang="en" class="page-type-section"> |
| <head prefix="og: http://ogp.me/ns#"> |
| <meta charset="utf-8"> |
| <title>attempt, recover - FreeMarker Manual</title> |
| <meta http-equiv="X-UA-Compatible" content="IE=edge"> |
| <meta name="viewport" content="width=device-width,initial-scale=1"> |
| <meta name="format-detection" content="telephone=no"> |
| <meta property="og:site_name" content="FreeMarker Manual"> |
| <meta property="og:title" content="attempt, recover"> |
| <meta property="og:locale" content="en_US"> |
| <meta property="og:url" content="http://example.com/ref_directive_attempt.html"> |
| <link rel="canonical" href="http://example.com/ref_directive_attempt.html"> |
| <link rel="icon" href="favicon.png" type="image/png"> |
| <link rel="stylesheet" type="text/css" href="docgen-resources/docgen.min.css?1594338519184"> |
| </head> |
| <body itemscope itemtype="https://schema.org/Code"> |
| <meta itemprop="url" content="http://example.com/"> |
| <meta itemprop="name" content="FreeMarker Manual"> |
| |
| <!--[if lte IE 9]> |
| <div style="background-color: #C00; color: #fff; padding: 12px 24px;">Please use a modern browser to view this website.</div> |
| <![endif]--><div class="header-top-bg"><div class="site-width header-top"><a class="logo" href="http://example.com" role="banner"> <img itemprop="image" src="logo.png" alt="My Logo"> |
| </a></div></div><div class="header-bottom-bg"><div class="site-width search-row"><a href="index.html" class="navigation-header">FreeMarker Manual</a><div class="navigation-header"></div></div><div class="site-width breadcrumb-row"><ul class="breadcrumb" itemscope itemtype="http://schema.org/BreadcrumbList"><li class="step-0" itemprop="itemListElement" itemscope itemtype="http://schema.org/ListItem"><a class="label" itemprop="item" href="index.html"><span itemprop="name">FreeMarker Manual</span></a></li><li class="step-1" itemprop="itemListElement" itemscope itemtype="http://schema.org/ListItem"><a class="label" itemprop="item" href="ref.html"><span itemprop="name">Reference</span></a></li><li class="step-2" itemprop="itemListElement" itemscope itemtype="http://schema.org/ListItem"><a class="label" itemprop="item" href="ref_directives.html"><span itemprop="name">Directive Reference</span></a></li><li class="step-3" itemprop="itemListElement" itemscope itemtype="http://schema.org/ListItem"><a class="label" itemprop="item" href="ref_directive_attempt.html"><span itemprop="name">attempt, recover</span></a></li></ul><div class="bookmarks" title="Bookmarks"><span class="sr-only">Bookmarks:</span><ul class="bookmark-list"><li><a href="alphaidx.html">Index</a></li><li><a href="gloss.html">Glossary</a></li><li><a href="ref.html">Reference</a></li><li><a href="app_faq.html">FAQ</a></li><li><a href="preface.html#test_target">Bőregér</a></li><li><a href="api/index.html">API</a></li><li><a href="../index.html">Home</a></li></ul></div></div></div> <div class="main-content site-width"> |
| <div class="content-wrapper"> |
| <div id="table-of-contents-wrapper" class="col-left"> |
| <script>var breadcrumb = ["FreeMarker Manual","Reference","Directive Reference","attempt, recover"];</script> |
| <script src="toc.js?1594338519184"></script> |
| <script src="docgen-resources/main.min.js?1594338519184"></script> |
| </div> |
| <div class="col-right"><div class="page-content"><div class="page-title"><div class="pagers top"><a class="paging-arrow previous" href="ref_directive_nt.html"><span>Previous</span></a><a class="paging-arrow next" href="ref_directive_visit.html"><span>Next</span></a></div><div class="title-wrapper"> |
| <h1 class="content-header header-section1" id="ref_directive_attempt" itemprop="headline">attempt, recover</h1> |
| </div></div><div class="page-menu"> |
| <div class="page-menu-title">Page Contents</div> |
| <ul><li><a class="page-menu-link" href="#autoid_120" data-menu-target="autoid_120">Synopsis</a></li><li><a class="page-menu-link" href="#autoid_121" data-menu-target="autoid_121">Description</a></li></ul> </div><a name="ref.directive.attempt"></a> <div class="callout note"> |
| <strong class="callout-label">Note:</strong> |
| |
| <p>The above format is supported starting from 2.3.3, earlier it |
| was |
| <code class="inline-code"><#attempt><em class="code-color">...</em><#recover><em class="code-color">...</em></#recover></code>, |
| which is still supported for backward compatibility. Furthermore, |
| these directives were introduced with FreeMarker 2.3.1, so they |
| aren't exist in 2.3.</p> |
| </div> |
| |
| |
| |
| |
| |
| <h2 class="content-header header-section2" id="autoid_120">Synopsis</h2> |
| |
| |
| |
| <pre class="metaTemplate"> |
| <code class="inline-code"><#attempt> |
| <em class="code-color">attempt block</em> |
| <#recover> |
| <em class="code-color">recover block</em> |
| </#attempt> |
| </code> |
| </pre> |
| |
| |
| <p>Where:</p> |
| |
| <ul> |
| <li> |
| <code class="inline-code"><em class="code-color">attempt |
| block</em></code>: Template block with any content. |
| This will be always executed, but if an error occurs during |
| that, all output from this block is rolled back, and the |
| <code class="inline-code"><em class="code-color">recover block</em></code> will |
| be executed. |
| </li> |
| |
| <li> |
| <code class="inline-code"><em class="code-color">recover |
| block</em></code>: Template block with any content. |
| This will be executed only if there was an error during the |
| execution of the <code class="inline-code"><em class="code-color">attempt |
| block</em></code>. You may print an error messages |
| here and such. |
| </li> |
| </ul> |
| |
| <p>The <code class="inline-code"><em class="code-color">recover</em></code> is |
| mandatory. <code class="inline-code">attempt</code>/<code class="inline-code">recover</code> can |
| be nested freely into other <code class="inline-code"><em class="code-color">attempt |
| block</em></code>s or <code class="inline-code"><em class="code-color">recover |
| block</em></code>s.</p> |
| |
| |
| |
| |
| |
| <h2 class="content-header header-section2" id="autoid_121">Description</h2> |
| |
| |
| <p>These directives are used if you want the page successfully |
| outputted even if the outputting of a certain part of the page |
| fails. If an error occurs during the execution of the |
| <code class="inline-code"><em class="code-color">attempt block</em></code>, then |
| the template execution is not aborted, but the |
| <code class="inline-code"><em class="code-color">recover block</em></code> is |
| executed instead of the <code class="inline-code"><em class="code-color">attempt |
| block</em></code>. If no error occurs during the |
| execution of the <code class="inline-code"><em class="code-color">attempt |
| block</em></code>, then the |
| <code class="inline-code"><em class="code-color">recover block</em></code> is |
| ignored. A simple example:</p> |
| |
| |
| |
| <div class="code-wrapper"><pre class="code-block code-template">Primary content |
| <#attempt> |
| Optional content: ${thisMayFails} |
| <#recover> |
| Ops! The optional content is not available. |
| </#attempt> |
| Primary content continued</pre></div> |
| |
| <p>If the <code class="inline-code">thisMayFails</code> variable doesn't exist, |
| then the output is:</p> |
| |
| |
| |
| <div class="code-wrapper"><pre class="code-block code-output">Primary content |
| Ops! The optional content is not available. |
| Primary content continued</pre></div> |
| |
| <p>If the <code class="inline-code">thisMayFails</code> variable exists and |
| it's value is <code class="inline-code">123</code>, then the output is:</p> |
| |
| |
| |
| <div class="code-wrapper"><pre class="code-block code-output">Primary content |
| Optional content: 123 |
| Primary content continued</pre></div> |
| |
| <p>The <code class="inline-code"><em class="code-color">attempt |
| block</em></code> has an all-or-none semantic: either |
| the entire content of the <code class="inline-code"><em class="code-color">attempt |
| block</em></code> is output (when there was no error), |
| or no output at all results from the execution of the |
| <code class="inline-code"><em class="code-color">attempt block</em></code> (when |
| there was an error). For example, above, the failure happens after |
| ``Optional content: '' was printed, still it is not there in the |
| output before the ``Ops!''. (<span class="marked-for-programmers">This is |
| implemented with the aggressive buffering of the output inside the |
| <code class="inline-code"><em class="code-color">attempt block</em></code>. Not |
| even the <code class="inline-code">flush</code> directive will send the output to |
| the client.</span>)</p> |
| |
| <p>To prevent misunderstandings coming from the above example: |
| <code class="inline-code">attempt</code>/<code class="inline-code">recover</code> is not (only) |
| for handling undefined variables (for that use <a href="dgui_template_exp.html#dgui_template_exp_missing">missing value handler |
| operators</a>). It can handle all kind of errors that occurs when |
| the block is executed (i.e. not syntactical errors, which are |
| detected earlier). And it's meant to enclose bigger template |
| fragments, where error can occur at various points. For example, you |
| have a part in your template that deals with printing |
| advertisements, but that's not the primary content of the page, so |
| you don't want your whole page be down just because some error |
| occurs with the printing of the advertisements (say, because of a |
| temporal database server faliure). So you put the whole |
| advertisement printing into an <code class="inline-code"><em class="code-color">attempt |
| block</em></code>.</p> |
| |
| <p>In some environments programmers configure FreeMarker so that |
| it doesn't abort template execution for certain errors, but |
| continues execution, possibly after printing some error indicator to |
| the output (<span class="marked-for-programmers">see more <a href="pgui_config_errorhandling.html">here...</a></span>). The |
| <code class="inline-code">attempt</code> directive doesn't consider such |
| suppressed errors as errors.</p> |
| |
| <p>Inside a <code class="inline-code"><em class="code-color">recover |
| block</em></code> the error message of the error is |
| available with the <code class="inline-code">error</code> <a href="ref_specvar.html">special variable</a>. Don't forget that |
| references to special variable are started with dot (for example: |
| <code class="inline-code">${.error}</code>).</p> |
| |
| <p><span class="marked-for-programmers">Errors occurring during template |
| execution are always <a href="pgui_misc_logging.html">logged</a>, even if they occur inside |
| an <code class="inline-code"><em class="code-color">attempt |
| block</em></code>.</span></p> |
| <div class="bottom-pagers-wrapper"><div class="pagers bottom"><a class="paging-arrow previous" href="ref_directive_nt.html"><span>Previous</span></a><a class="paging-arrow next" href="ref_directive_visit.html"><span>Next</span></a></div></div></div></div> </div> |
| </div> |
| <div class="site-footer"><div class="site-width"><div class="footer-top"><div class="col-left sitemap"></div><div class="col-right"><a class="xxe" href="http://www.xmlmind.com/xmleditor/" rel="nofollow" title="Edited with XMLMind XML Editor"><span>Edited with XMLMind XML Editor</span></a></div></div><div class="footer-bottom"> <p class="last-generated"> |
| Last generated: |
| <time itemprop="dateModified" datetime="2020-07-09T23:48:39Z" title="Thursday, July 9, 2020 11:48:39 PM GMT">2020-07-09 23:48:39 GMT</time> </p> |
| <p class="copyright"> |
| © <span itemprop="copyrightYear">1999</span>–2020 |
| <a itemtype="http://schema.org/Organization" itemprop="copyrightHolder" href="https://apache.org/">The Apache Software Foundation</a> </p> |
| </div></div></div></body> |
| </html> |