1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Relative Link Resolution [Universal Feed Parser]</title>
<link rel="stylesheet" href="feedparser.css" type="text/css">
<link rev="made" href="mailto:mark@diveintomark.org">
<meta name="generator" content="DocBook XSL Stylesheets V1.65.1">
<meta name="keywords" content="RSS, Atom, CDF, XML, feed, parser, Python">
<link rel="start" href="index.html" title="Documentation">
<link rel="up" href="advanced.html" title="Advanced Features">
<link rel="prev" href="namespace-handling.html" title="Namespace Handling">
<link rel="next" href="version-detection.html" title="Feed Type and Version Detection">
</head>
<body id="feedparser-org" class="docs">
<div class="z" id="intro"><div class="sectionInner"><div class="sectionInner2">
<div class="s" id="pageHeader">
<h1><a href="/"><span>Universal Feed Parser</span></a></h1>
<p><span>Parse RSS and Atom feeds in Python. 3000 unit tests. Open source.</span></p>
</div>
<div class="s" id="quickSummary"><ul>
<li class="li1">
<a href="http://sourceforge.net/projects/feedparser/"><span>Download</span></a> ·</li>
<li class="li2">
<a href="http://feedparser.org/docs/"><span>Documentation</span></a> ·</li>
<li class="li3">
<a href="http://feedparser.org/tests/"><span>Unit tests</span></a> ·</li>
<li class="li4"><a href="http://sourceforge.net/tracker/?func=browse&group_id=112328&atid=661937"><span>Report a bug</span></a></li>
</ul></div>
</div></div></div>
<div id="main"><div id="mainInner">
<p id="breadcrumb">You are here: <a href="index.html">Documentation</a> → <a href="advanced.html">Advanced Features</a> → <span class="thispage">Relative Link Resolution</span></p>
<div class="section" lang="en">
<div class="titlepage">
<div>
<div><h2 class="title">
<a name="advanced.base" class="skip" href="#advanced.base" title="link to this section"><img src="images/permalink.gif" alt="[link]" title="link to this section" width="8" height="9"></a> Relative Link Resolution</h2></div>
<div><div class="abstract">
<h3 class="title"></h3>
<p>Many feed elements and attributes are <acronym title="Uniform Resource Identifier">URI</acronym>s. <span class="application">Universal Feed Parser</span> resolves relative <acronym title="Uniform Resource Identifier">URI</acronym>s according to the <a href="http://www.w3.org/TR/xmlbase/"><acronym title="Extensible Markup Language">XML</acronym>:Base</a> specification. We'll see how that works in a minute, but first let's talk about which values are treated as <acronym title="Uniform Resource Identifier">URI</acronym>s.</p>
</div></div>
</div>
<div></div>
</div>
<div class="section" lang="en">
<div class="titlepage">
<div><div><h3 class="title">
<a name="advanced.base.which" class="skip" href="#advanced.base.which" title="link to this section"><img src="images/permalink.gif" alt="[link]" title="link to this section" width="8" height="9"></a> Which Values Are <acronym title="Uniform Resource Identifier">URI</acronym>s</h3></div></div>
<div></div>
</div>
<p>These feed elements are treated as <acronym title="Uniform Resource Identifier">URI</acronym>s, and resolved if they are relative:</p>
<div class="itemizedlist"><ul>
<li><a href="reference-feed-link.html" title="feed.link">feed.link</a></li>
<li><a href="reference-feed-links.html#reference.feed.links.href" title="feed.links[i].href">feed.links[i].href</a></li>
<li><a href="reference-feed-generator_detail.html#reference.feed.generator_detail.href" title="feed.generator_detail.href">feed.generator_detail.href</a></li>
<li><a href="reference-feed-id.html" title="feed.id">feed.id</a></li>
<li><a href="reference-feed-image.html#reference.feed.image.href" title="feed.image.href">feed.image.href</a></li>
<li><a href="reference-feed-image.html#reference.feed.image.link" title="feed.image.link">feed.image.link</a></li>
<li><a href="reference-feed-textinput.html#reference.feed.textinput.link" title="feed.textinput.link">feed.textinput.link</a></li>
<li><a href="reference-feed-author_detail.html#reference.feed.author_detail.href" title="feed.author_detail.href">feed.author_detail.href</a></li>
<li><a href="reference-feed-publisher_detail.html#reference.feed.publisher_detail.href" title="feed.publisher_detail.href">feed.publisher_detail.href</a></li>
<li><a href="reference-feed-contributors.html#reference.feed.contributors.href" title="feed.contributors[i].href">feed.contributors[i].href</a></li>
<li><a href="reference-feed-docs.html" title="feed.docs">feed.docs</a></li>
<li><a href="reference-feed-license.html" title="feed.license">feed.license</a></li>
<li><a href="reference-entry-link.html" title="entries[i].link">entries[i].link</a></li>
<li><a href="reference-entry-links.html#reference.entry.links.href" title="entries[i].links[j].href">entries[i].links[j].href</a></li>
<li><a href="reference-entry-id.html" title="entries[i].id">entries[i].id</a></li>
<li><a href="reference-entry-author_detail.html#reference.entry.author_detail.href" title="entries[i].author_detail.href">entries[i].author_detail.href</a></li>
<li><a href="reference-entry-publisher_detail.html#reference.entry.publisher_detail.href" title="entries[i].publisher_detail.href">entries[i].publisher_detail.href</a></li>
<li><a href="reference-entry-contributors.html#reference.entry.contributors.href" title="entries[i].contributors[j].href">entries[i].contributors[j].href</a></li>
<li><a href="reference-entry-enclosures.html#reference.entry.enclosures.href" title="entries[i].enclosures[j].href">entries[i].enclosures[j].href</a></li>
<li><a href="reference-entry-source.html#reference.entry.source.author_detail.href" title="entries[i].source.author_detail.href">entries[i].source.author_detail.href</a></li>
<li><a href="reference-entry-source.html#reference.entry.source.contributors.href" title="entries[i].source.contributors[j].href">entries[i].source.contributors[j].href</a></li>
<li><a href="reference-entry-source.html#reference.entry.source.links.href" title="entries[i].source.links[j].href">entries[i].source.links[j].href</a></li>
<li><a href="reference-entry-comments.html" title="entries[i].comments">entries[i].comments</a></li>
<li><a href="reference-entry-license.html" title="entries[i].license">entries[i].license</a></li>
</ul></div>
<p>In addition, several feed elements may contain <acronym title="HyperText Markup Language">HTML</acronym> or <acronym title="Extensible HyperText Markup Language">XHTML</acronym> markup. Certain elements and attributes in <acronym title="HyperText Markup Language">HTML</acronym> can be relative <acronym title="Uniform Resource Identifier">URI</acronym>s, and <span class="application">Universal Feed Parser</span> will resolve these <acronym title="Uniform Resource Identifier">URI</acronym>s according to the same rules as the feed elements listed above.</p>
<p>These feed elements may contain <acronym title="HyperText Markup Language">HTML</acronym> or <acronym title="Extensible HyperText Markup Language">XHTML</acronym> markup. In Atom feeds, whether these elements are treated as <acronym title="HyperText Markup Language">HTML</acronym> depends on the value of the <tt class="sgmltag-attribute">type</tt> attribute. In <acronym title="Rich Site Summary">RSS</acronym> feeds, these values are always treated as <acronym title="HyperText Markup Language">HTML</acronym>.</p>
<div class="itemizedlist"><ul>
<li>
<a href="reference-feed-title.html" title="feed.title">feed.title</a> (<a href="reference-feed-title_detail.html#reference.feed.title_detail.value" title="feed.title_detail.value">feed.title_detail.value</a>)</li>
<li>
<a href="reference-feed-subtitle.html" title="feed.subtitle">feed.subtitle</a> (<a href="reference-feed-subtitle_detail.html#reference.feed.subtitle_detail.value" title="feed.subtitle_detail.value">feed.subtitle_detail.value</a>))</li>
<li>
<a href="reference-feed-info.html" title="feed.info">feed.info</a> (<a href="reference-feed-info-detail.html#reference.feed.info_detail.value" title="feed.info_detail.value">feed.info_detail.value</a>)</li>
<li>
<a href="reference-feed-rights.html" title="feed.rights">feed.rights</a> (<a href="reference-feed-rights_detail.html#reference.feed.rights_detail.value" title="feed.rights_detail.value">feed.rights_detail.value</a>)</li>
<li>
<a href="reference-entry-title.html" title="entries[i].title">entries[i].title</a> (<a href="reference-entry-title_detail.html#reference.entry.title_detail.value" title="entries[i].title_detail.value">entries[i].title_detail.value</a>)</li>
<li>
<a href="reference-entry-summary.html" title="entries[i].summary">entries[i].summary</a> (<a href="reference-entry-summary_detail.html#reference.entry.summary_detail.value" title="entries[i].summary_detail.value">entries[i].summary_detail.value</a>)</li>
<li><a href="reference-entry-content.html#reference.entry.content.value" title="entries[i].content[j].value">entries[i].content[j].value</a></li>
</ul></div>
<p>When any of these feed elements contains <acronym title="HyperText Markup Language">HTML</acronym> or <acronym title="Extensible HyperText Markup Language">XHTML</acronym> markup, the following <acronym title="HyperText Markup Language">HTML</acronym> elements are treated as <acronym title="Uniform Resource Identifier">URI</acronym>s and are resolved if they are relative:</p>
<div class="itemizedlist"><ul>
<li><tt class="sgmltag-element"><a href="..."></tt></li>
<li><tt class="sgmltag-element"><applet codebase="..."></tt></li>
<li><tt class="sgmltag-element"><area href="..."></tt></li>
<li><tt class="sgmltag-element"><blockquote cite="..."></tt></li>
<li><tt class="sgmltag-element"><body background="..."></tt></li>
<li><tt class="sgmltag-element"><del cite="..."></tt></li>
<li><tt class="sgmltag-element"><form action="..."></tt></li>
<li><tt class="sgmltag-element"><frame longdesc="..."></tt></li>
<li><tt class="sgmltag-element"><frame src="..."></tt></li>
<li><tt class="sgmltag-element"><iframe longdesc="..."></tt></li>
<li><tt class="sgmltag-element"><iframe src="..."></tt></li>
<li><tt class="sgmltag-element"><head profile="..."></tt></li>
<li><tt class="sgmltag-element"><img longdesc="..."></tt></li>
<li><tt class="sgmltag-element"><img src="..."></tt></li>
<li><tt class="sgmltag-element"><img usemap="..."></tt></li>
<li><tt class="sgmltag-element"><input src="..."></tt></li>
<li><tt class="sgmltag-element"><input usemap="..."></tt></li>
<li><tt class="sgmltag-element"><ins cite="..."></tt></li>
<li><tt class="sgmltag-element"><link href="..."></tt></li>
<li><tt class="sgmltag-element"><object classid="..."></tt></li>
<li><tt class="sgmltag-element"><object codebase="..."></tt></li>
<li><tt class="sgmltag-element"><object data="..."></tt></li>
<li><tt class="sgmltag-element"><object usemap="..."></tt></li>
<li><tt class="sgmltag-element"><q cite="..."></tt></li>
<li><tt class="sgmltag-element"><script src="..."></tt></li>
</ul></div>
</div>
<div class="section" lang="en">
<div class="titlepage">
<div><div><h3 class="title">
<a name="advanced.base.how" class="skip" href="#advanced.base.how" title="link to this section"><img src="images/permalink.gif" alt="[link]" title="link to this section" width="8" height="9"></a> How Relative <acronym title="Uniform Resource Identifier">URI</acronym>s Are Resolved</h3></div></div>
<div></div>
</div>
<p><span class="application">Universal Feed Parser</span> resolves relative <acronym title="Uniform Resource Identifier">URI</acronym>s according to the <a href="http://www.w3.org/TR/xmlbase/"><acronym title="Extensible Markup Language">XML</acronym>:Base</a> specification. This defines a hierarchical inheritance system, where one element can define the base <acronym title="Uniform Resource Identifier">URI</acronym> for itself and all of its child elements, using an <tt class="sgmltag-attribute">xml:base</tt> attribute. A child element can then override its parent's base <acronym title="Uniform Resource Identifier">URI</acronym> by redeclaring <tt class="sgmltag-attribute">xml:base</tt> to a different value.</p>
<p>If no <tt class="sgmltag-attribute">xml:base</tt> is specified, the feed has a default base <acronym title="Uniform Resource Identifier">URI</acronym> defined in the <tt class="literal">Content-Location</tt> <acronym title="Hypertext Transfer Protocol">HTTP</acronym> header.</p>
<p>If no <tt class="literal">Content-Location</tt> <acronym title="Hypertext Transfer Protocol">HTTP</acronym> header is present, the <acronym title="Uniform Resource Locator">URL</acronym> used to retrieve the feed itself is the default base <acronym title="Uniform Resource Identifier">URI</acronym> for all relative links within the feed. If the feed was retrieved via an <acronym title="Hypertext Transfer Protocol">HTTP</acronym> redirect (any <acronym title="Hypertext Transfer Protocol">HTTP</acronym> 3xx status code), then the final <acronym title="Uniform Resource Locator">URL</acronym> of the feed is the default base <acronym title="Uniform Resource Identifier">URI</acronym>.</p>
<p>For example, an <tt class="sgmltag-attribute">xml:base</tt> on the root-level element sets the base <acronym title="Uniform Resource Identifier">URI</acronym> for all <acronym title="Uniform Resource Identifier">URI</acronym>s in the feed.</p>
<div class="example">
<a name="id4959103" class="skip" href="#id4959103" title="link to this example"><img src="images/permalink.gif" alt="[link]" title="link to this example" width="8" height="9"></a> <h3 class="title">Example: <tt class="sgmltag-attribute">xml:base</tt> on the root-level element</h3>
<pre class="screen"><tt class="prompt">>>> </tt><span class="userinput"><font color='navy'><b>import</b></font> feedparser</span>
<tt class="prompt">>>> </tt><span class="userinput">d = feedparser.parse("<a href="http://feedparser.org/docs/examples/base.xml">http://feedparser.org/docs/examples/base.xml</a>")</span>
<tt class="prompt">>>> </tt><span class="userinput">d.feed.link</span>
<span class="computeroutput">u'http://example.org/index.html'</span>
<tt class="prompt">>>> </tt><span class="userinput">d.feed.generator_detail.href</span>
<span class="computeroutput">u'http://example.org/generator/'</span></pre>
</div>
<p>An <tt class="sgmltag-attribute">xml:base</tt> attribute on an <tt class="sgmltag-element"><entry></tt> overrides the <tt class="sgmltag-attribute">xml:base</tt> on the parent <tt class="sgmltag-element"><feed></tt>.</p>
<div class="example">
<a name="id4959198" class="skip" href="#id4959198" title="link to this example"><img src="images/permalink.gif" alt="[link]" title="link to this example" width="8" height="9"></a> <h3 class="title">Example: Overriding <tt class="sgmltag-attribute">xml:base</tt> on an <tt class="sgmltag-element"><entry></tt></h3>
<pre class="screen"><tt class="prompt">>>> </tt><span class="userinput"><font color='navy'><b>import</b></font> feedparser</span>
<tt class="prompt">>>> </tt><span class="userinput">d = feedparser.parse("<a href="http://feedparser.org/docs/examples/base.xml">http://feedparser.org/docs/examples/base.xml</a>")</span>
<tt class="prompt">>>> </tt><span class="userinput">d.entries[0].link</span>
<span class="computeroutput">u'http://example.org/archives/000001.html'</span>
<tt class="prompt">>>> </tt><span class="userinput">d.entries[0].author_detail.href</span>
<span class="computeroutput">u'http://example.org/about/'</span></pre>
</div>
<p>An <tt class="sgmltag-attribute">xml:base</tt> on <tt class="sgmltag-element"><content></tt> overrides the <tt class="sgmltag-attribute">xml:base</tt> on the parent <tt class="sgmltag-element"><entry></tt>. In addition, whatever the base <acronym title="Uniform Resource Identifier">URI</acronym> is for the <tt class="sgmltag-element"><content></tt> element (whether defined directly on the <tt class="sgmltag-element"><content></tt> element, or inherited from the parent element) is used as the base <acronym title="Uniform Resource Identifier">URI</acronym> for the embedded <acronym title="HyperText Markup Language">HTML</acronym> or <acronym title="Extensible HyperText Markup Language">XHTML</acronym> markup within the <tt class="sgmltag-element">content</tt>.</p>
<div class="example">
<a name="id4959342" class="skip" href="#id4959342" title="link to this example"><img src="images/permalink.gif" alt="[link]" title="link to this example" width="8" height="9"></a> <h3 class="title">Example: Relative links within embedded <acronym title="HyperText Markup Language">HTML</acronym></h3>
<pre class="screen"><tt class="prompt">>>> </tt><span class="userinput"><font color='navy'><b>import</b></font> feedparser</span>
<tt class="prompt">>>> </tt><span class="userinput">d = feedparser.parse("<a href="http://feedparser.org/docs/examples/base.xml">http://feedparser.org/docs/examples/base.xml</a>")</span>
<tt class="prompt">>>> </tt><span class="userinput">d.entries[0].content[0].value</span>
<span class="computeroutput">u'<p id="anchor1"><a href="http://example.org/archives/000001.html#anchor2">skip to anchor 2</a></p>
<p>Some content</p>
<p id="anchor2">This is anchor 2</p>'</span></pre>
</div>
<p>The <tt class="sgmltag-attribute">xml:base</tt> affects other attributes in the element in which it is declared.</p>
<div class="example">
<a name="id4959417" class="skip" href="#id4959417" title="link to this example"><img src="images/permalink.gif" alt="[link]" title="link to this example" width="8" height="9"></a> <h3 class="title">Example: <tt class="sgmltag-attribute">xml:base</tt> and sibling attributes</h3>
<pre class="screen"><tt class="prompt">>>> </tt><span class="userinput"><font color='navy'><b>import</b></font> feedparser</span>
<tt class="prompt">>>> </tt><span class="userinput">d = feedparser.parse("<a href="http://feedparser.org/docs/examples/base.xml">http://feedparser.org/docs/examples/base.xml</a>")</span>
<tt class="prompt">>>> </tt><span class="userinput">d.entries[0].links[1].rel</span>
<span class="computeroutput">u'service.edit'</span>
<tt class="prompt">>>> </tt><span class="userinput">d.entries[0].links[1].href</span>
<span class="computeroutput">u'http://example.com/api/client/37'</span></pre>
</div>
<p>If no <tt class="sgmltag-attribute">xml:base</tt> is specified on the root-level element, the default base <acronym title="Uniform Resource Identifier">URI</acronym> is given in the <tt class="literal">Content-Location</tt> <acronym title="Hypertext Transfer Protocol">HTTP</acronym> header. This can still be overridden by any child element that declares an <tt class="sgmltag-attribute">xml:base</tt> attribute.</p>
<div class="example">
<a name="id4959531" class="skip" href="#id4959531" title="link to this example"><img src="images/permalink.gif" alt="[link]" title="link to this example" width="8" height="9"></a> <h3 class="title">Example: <tt class="literal">Content-Location</tt> <acronym title="Hypertext Transfer Protocol">HTTP</acronym> header</h3>
<pre class="screen"><tt class="prompt">>>> </tt><span class="userinput"><font color='navy'><b>import</b></font> feedparser</span>
<tt class="prompt">>>> </tt><span class="userinput">d = feedparser.parse("<a href="http://feedparser.org/docs/examples/http_base.xml">http://feedparser.org/docs/examples/http_base.xml</a>")</span>
<tt class="prompt">>>> </tt><span class="userinput">d.feed.link</span>
<span class="computeroutput">u'http://example.org/index.html'</span>
<tt class="prompt">>>> </tt><span class="userinput">d.entries[0].link</span>
<span class="computeroutput">u'http://example.org/archives/000001.html'</span></pre>
</div>
<p>Finally, if no root-level <tt class="sgmltag-attribute">xml:base</tt> is declared, and no <tt class="literal">Content-Location</tt> <acronym title="Hypertext Transfer Protocol">HTTP</acronym> header is present, the <acronym title="Uniform Resource Locator">URL</acronym> of the feed itself is the default base <acronym title="Uniform Resource Identifier">URI</acronym>. Again, this can still be overridden by any element that declares an <tt class="sgmltag-attribute">xml:base</tt> attribute.</p>
<div class="example">
<a name="id4959662" class="skip" href="#id4959662" title="link to this example"><img src="images/permalink.gif" alt="[link]" title="link to this example" width="8" height="9"></a> <h3 class="title">Example: Feed <acronym title="Uniform Resource Locator">URL</acronym> as default base <acronym title="Uniform Resource Identifier">URI</acronym></h3>
<pre class="screen"><tt class="prompt">>>> </tt><span class="userinput"><font color='navy'><b>import</b></font> feedparser</span>
<tt class="prompt">>>> </tt><span class="userinput">d = feedparser.parse("<a href="http://feedparser.org/docs/examples/no_base.xml">http://feedparser.org/docs/examples/no_base.xml</a>")</span>
<tt class="prompt">>>> </tt><span class="userinput">d.feed.link</span>
<span class="computeroutput">u'http://feedparser.org/docs/examples/index.html</span>
<tt class="prompt">>>> </tt><span class="userinput">d.entries[0].link</span>
<span class="computeroutput">u'http://example.org/archives/000001.html'</span></pre>
</div>
</div>
</div>
<div style="float: left">← <a class="NavigationArrow" href="namespace-handling.html">Namespace Handling</a>
</div>
<div style="text-align: right">
<a class="NavigationArrow" href="version-detection.html">Feed Type and Version Detection</a> →</div>
<hr style="clear:both">
<div class="footer"><p class="copyright">Copyright © 2004, 2005, 2006 Mark Pilgrim</p></div>
</div></div>
</body>
</html>
|
