<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Testing for Existence — feedparser 5.1.3 documentation</title>
<link rel="stylesheet" href="_static/default.css" type="text/css" />
<link rel="stylesheet" href="_static/pygments.css" type="text/css" />
<link rel="stylesheet" href="_static/feedparser.css" type="text/css" />
<script type="text/javascript">
var DOCUMENTATION_OPTIONS = {
URL_ROOT: '',
VERSION: '5.1.3',
COLLAPSE_INDEX: false,
FILE_SUFFIX: '.html',
HAS_SOURCE: true
};
</script>
<script type="text/javascript" src="_static/jquery.js"></script>
<script type="text/javascript" src="_static/underscore.js"></script>
<script type="text/javascript" src="_static/doctools.js"></script>
<link rel="top" title="feedparser 5.1.3 documentation" href="index.html" />
<link rel="up" title="Basic Features" href="basic.html" />
<link rel="next" title="Advanced Features" href="advanced.html" />
<link rel="prev" title="Uncommon Atom Elements" href="uncommon-atom.html" />
</head>
<body>
<div class="related">
<h3>Navigation</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="genindex.html" title="General Index"
accesskey="I">index</a></li>
<li class="right" >
<a href="advanced.html" title="Advanced Features"
accesskey="N">next</a> |</li>
<li class="right" >
<a href="uncommon-atom.html" title="Uncommon Atom Elements"
accesskey="P">previous</a> |</li>
<li><a href="index.html">feedparser 5.1.3 documentation</a> »</li>
<li><a href="basic.html" accesskey="U">Basic Features</a> »</li>
</ul>
</div>
<div class="document">
<div class="documentwrapper">
<div class="bodywrapper">
<div class="body">
<div class="section" id="testing-for-existence">
<h1>Testing for Existence<a class="headerlink" href="#testing-for-existence" title="Permalink to this headline">¶</a></h1>
<p>Feeds in the real world may be missing elements, even elements that are
required by the specification. You should always test for the existence of an
element before getting its value. Never assume an element is present.</p>
<p>To test whether elements exist, you can use standard <strong class="program">Python</strong>
dictionary idioms.</p>
<div class="section" id="testing-if-elements-are-present">
<h2>Testing if elements are present<a class="headerlink" href="#testing-if-elements-are-present" title="Permalink to this headline">¶</a></h2>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">feedparser</span>
<span class="gp">>>> </span><span class="n">d</span> <span class="o">=</span> <span class="n">feedparser</span><span class="o">.</span><span class="n">parse</span><span class="p">(</span><span class="s">'http://feedparser.org/docs/examples/atom10.xml'</span><span class="p">)</span>
<span class="gp">>>> </span><span class="s">'title'</span> <span class="ow">in</span> <span class="n">d</span><span class="o">.</span><span class="n">feed</span>
<span class="go">True</span>
<span class="gp">>>> </span><span class="s">'ttl'</span> <span class="ow">in</span> <span class="n">d</span><span class="o">.</span><span class="n">feed</span>
<span class="go">False</span>
<span class="gp">>>> </span><span class="n">d</span><span class="o">.</span><span class="n">feed</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="s">'title'</span><span class="p">,</span> <span class="s">'No title'</span><span class="p">)</span>
<span class="go">u'Sample feed'</span>
<span class="gp">>>> </span><span class="n">d</span><span class="o">.</span><span class="n">feed</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="s">'ttl'</span><span class="p">,</span> <span class="mi">60</span><span class="p">)</span>
<span class="go">60</span>
</pre></div>
</div>
</div>
</div>
</div>
</div>
</div>
<div class="sphinxsidebar">
<div class="sphinxsidebarwrapper">
<h3><a href="index.html">Table Of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">Testing for Existence</a><ul>
<li><a class="reference internal" href="#testing-if-elements-are-present">Testing if elements are present</a></li>
</ul>
</li>
</ul>
<h4>Previous topic</h4>
<p class="topless"><a href="uncommon-atom.html"
title="previous chapter">Uncommon Atom Elements</a></p>
<h4>Next topic</h4>
<p class="topless"><a href="advanced.html"
title="next chapter">Advanced Features</a></p>
<h3>This Page</h3>
<ul class="this-page-menu">
<li><a href="_sources/basic-existence.txt"
rel="nofollow">Show Source</a></li>
</ul>
<div id="searchbox" style="display: none">
<h3>Quick search</h3>
<form class="search" action="search.html" method="get">
<input type="text" name="q" />
<input type="submit" value="Go" />
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
<p class="searchtip" style="font-size: 90%">
Enter search terms or a module, class or function name.
</p>
</div>
<script type="text/javascript">$('#searchbox').show(0);</script>
</div>
</div>
<div class="clearer"></div>
</div>
<div class="related">
<h3>Navigation</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="genindex.html" title="General Index"
>index</a></li>
<li class="right" >
<a href="advanced.html" title="Advanced Features"
>next</a> |</li>
<li class="right" >
<a href="uncommon-atom.html" title="Uncommon Atom Elements"
>previous</a> |</li>
<li><a href="index.html">feedparser 5.1.3 documentation</a> »</li>
<li><a href="basic.html" >Basic Features</a> »</li>
</ul>
</div>
<div class="footer">
© Copyright 2004-2008 Mark Pilgrim, 2010-2012 Kurt McKee.
Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 1.1.3.
</div>
</body>
</html>
