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Mark Pilgrim
426 lines
26 KiB
HTML
426 lines
26 KiB
HTML
<!DOCTYPE html>
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<meta charset=utf-8>
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<title>XML - Dive into Python 3</title>
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<link rel=stylesheet type=text/css href=dip3.css>
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<style>
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body{counter-reset:h1 13}
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mark{display:inline}
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<link rel=stylesheet type=text/css media='only screen and (max-device-width: 480px)' href=mobile.css>
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<form action=http://www.google.com/cse><div><input type=hidden name=cx value=014021643941856155761:l5eihuescdw><input type=hidden name=ie value=UTF-8> <input name=q size=25> <input type=submit name=root value=Search></div></form>
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<p>You are here: <a href=index.html>Home</a> <span>‣</span> <a href=table-of-contents.html#xml>Dive Into Python 3</a> <span>‣</span>
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<p id=level>Difficulty level: <span title=beginner>♦♦♦♢♢</span>
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<h1>XML</h1>
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<blockquote class=q>
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<p><span>❝</span> FIXME <span>❞</span><br>— FIXME
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</blockquote>
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<p id=toc>
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<h2 id=divingin>Diving In</h2>
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<p class=f>Most of the chapters in this book have centered around a piece of sample code. But XML isn’t about code; it’s about data. One common use of XML is “syndication feeds” that list the latest articles on a blog, forum, or other frequently-updated website. Most popular blogging software can produce a feed and update it whenever new articles, discussion threads, or blog posts are published. You can follow a blog by “subscribing” to its feed, and you can follow multiple blogs with a dedicated “<a href=http://en.wikipedia.org/wiki/List_of_feed_aggregators>feed aggregator</a>” like <a href=http://www.google.com/reader/>Google Reader</a>.
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<p>Here, then, is the XML data we’ll be working with in this chapter. It’s a feed — specifically, an <a href=http://atompub.org/rfc4287.html>Atom syndication feed</a>.
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<p class=d>[<a href=examples/feed.xml>download <code>feed.xml</code></a>]
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<pre><code><?xml version="1.0" encoding="utf-8"?>
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<feed xmlns="http://www.w3.org/2005/Atom" xml:lang="en">
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<title>dive into mark</title>
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<subtitle>currently between addictions</subtitle>
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<id>tag:diveintomark.org,2001-07-29:/</id>
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<updated>2009-03-27T21:56:07Z</updated>
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<link rel="alternate" type="text/html" href="http://diveintomark.org/"/>
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<link rel="self" type="application/atom+xml" href="http://diveintomark.org/feed/"/>
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<entry>
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<author>
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<name>Mark</name>
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<uri>http://diveintomark.org/</uri>
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</author>
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<title>Dive into history, 2009 edition</title>
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<link rel="alternate" type="text/html"
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href="http://diveintomark.org/archives/2009/03/27/dive-into-history-2009-edition"/>
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<id>tag:diveintomark.org,2009-03-27:/archives/20090327172042</id>
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<updated>2009-03-27T21:56:07Z</updated>
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<published>2009-03-27T17:20:42Z</published>
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<category scheme="http://diveintomark.org" term="diveintopython"/>
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<category scheme="http://diveintomark.org" term="docbook"/>
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<category scheme="http://diveintomark.org" term="html"/>
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<summary type="html">Putting an entire chapter on one page sounds
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bloated, but consider this &amp;mdash; my longest chapter so far
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would be 75 printed pages, and it loads in under 5 seconds&amp;hellip;
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On dialup.</summary>
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</entry>
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<entry>
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<author>
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<name>Mark</name>
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<uri>http://diveintomark.org/</uri>
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</author>
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<title>Accessibility is a harsh mistress</title>
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<link rel="alternate" type="text/html"
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href="http://diveintomark.org/archives/2009/03/21/accessibility-is-a-harsh-mistress"/>
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<id>tag:diveintomark.org,2009-03-21:/archives/20090321200928</id>
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<updated>2009-03-22T01:05:37Z</updated>
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<published>2009-03-21T20:09:28Z</published>
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<category scheme="http://diveintomark.org" term="accessibility"/>
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<summary type="html">The accessibility orthodoxy does not permit people to
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question the value of features that are rarely useful and rarely used.</summary>
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</entry>
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<entry>
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<author>
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<name>Mark</name>
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<uri>http://diveintomark.org/</uri>
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</author>
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<title>A gentle introduction to video encoding, part 1: container formats</title>
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<link rel="alternate" type="text/html"
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href="http://diveintomark.org/archives/2008/12/18/give-part-1-container-formats"/>
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<id>tag:diveintomark.org,2008-12-18:/archives/20081218155422</id>
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<updated>2009-01-11T19:39:22Z</updated>
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<published>2008-12-18T15:54:22Z</published>
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<category scheme="http://diveintomark.org" term="asf"/>
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<category scheme="http://diveintomark.org" term="avi"/>
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<category scheme="http://diveintomark.org" term="encoding"/>
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<category scheme="http://diveintomark.org" term="flv"/>
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<category scheme="http://diveintomark.org" term="GIVE"/>
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<category scheme="http://diveintomark.org" term="mp4"/>
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<category scheme="http://diveintomark.org" term="ogg"/>
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<category scheme="http://diveintomark.org" term="video"/>
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<summary type="html">These notes will eventually become part of a
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tech talk on video encoding.</summary>
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</entry>
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</feed></code></pre>
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<h2 id=xml-intro>A 5-Minute Crash Course in XML</h2>
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<p>If you already know about XML, you can skip this section.
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<p>XML is a generalized way of describing hierarchical structured data. An XML <i>document</i> contains one or more <i>elements</i>, which are delimited by <i>start and end tags</i>. This is a complete (albeit boring) XML document:
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<pre class=nd><code><a><foo> <span>①</span></a>
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<a></foo> <span>②</span></a></code></pre>
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<ol>
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<li>This is the <i>start tag</i> of the <code>foo</code> element.
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<li>This is the matching <i>end tag</i> of the <code>foo</code> element. Like balancing parentheses in writing or mathematics or code, every start tag much be <i>closed</i> (matched) by a corresponding end tag.
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</ol>
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<p>Elements can be <i>nested</i> to any depth. An element <code>bar</code> inside an element <code>foo</code> is said to be a <i>subelement</i> or <i>child</i> of <code>foo</code>.
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<pre class=nd><code><foo>
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<mark><bar></bar></mark>
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</foo>
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</code></pre>
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<p>The first element in every XML document is called the <i>root element</i>. An XML document can only have one root element. The following is <strong>not an XML document</strong>, because it has two root elements:
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<pre class=nd><code><foo></foo>
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<bar></bar></code></pre>
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<p>Elements can have <i>attributes</i>, which are name-value pairs. Attributes are listed within the start tag of an element and separated by whitespace. <i>Attribute names</i> can not be repeated within an element. <i>Attribute values</i> must be quoted.
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<pre class=nd><code><a><foo <mark>lang="en"</mark>> <span>①</span></a>
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<a> <bar <mark>lang="fr"</mark>></bar> <span>②</span></a>
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</foo>
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</code></pre>
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<ol>
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<li>The <code>foo</code> element has one attribute, named <code>lang</code>. The value of its <code>lang</code> attribute is <code>en</code>.
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<li>The <code>bar</code> element has one attribute, named <code>lang</code>. The value of its <code>lang</code> attribute is <code>fr</code>. This doesn’t conflict with the <code>foo</code> element in any way. Each element has its own set of attributes.
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</ol>
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<p>If an element has more than one attribute, the ordering of the attributes is not significant. An element’s attributes form an unordered set of keys and values, like a Python dictionary.
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<p>Elements can have <i>text content</i>.
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<pre class=nd><code><foo lang="en">
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<bar lang="fr"><mark>PapayaWhip</mark></bar>
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</foo>
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</code></pre>
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<p>Elements that contain no text and no children are <i>empty</i>.
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<pre class=nd><code><foo></foo></code></pre>
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<p>There is a shorthand for writing empty elements. By putting a <code>/</code> character in the start tag, you can skip the end tag altogther. The XML document in the previous example could be written like this instead:
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<pre class=nd><code><foo<mark>/</mark>></code></pre>
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<p>Like Python functions can be declared in different <i>modules</i>, XML elements can be declared in different <i>namespaces</i>. Namespaces usually look like URLs. You use an <code>xmlns</code> declaration to define a <i>default namespace</i>. A namespace declaration looks similar to an attribute, but it has a different purpose.
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<pre class=nd><a><code><feed <mark>xmlns="http://www.w3.org/2005/Atom"</mark>> <span>①</span></a>
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<a> <title>dive into mark</title> <span>②</span></a>
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</feed>
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</code></pre>
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<ol>
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<li>The <code>feed</code> element is in the <code>http://www.w3.org/2005/Atom</code> namespace.
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<li>The <code>title</code> element is also in the <code>http://www.w3.org/2005/Atom</code> namespace. The namespace declaration affects the element where it’s declared, plus all child elements.
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</ol>
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<p>You can also use an <code>xmlns:<var>prefix</var></code> declaration to define a namespace and associate it with a <i>prefix</i>. Then each element in that namespace must be explicitly declared with the prefix.
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<pre class=nd><a><code><atom:feed <mark>xmlns:atom="http://www.w3.org/2005/Atom"</mark>> <span>①</span></a>
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<a> <atom:title>dive into mark</atom:title> <span>②</span></a>
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</atom:feed>
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</code></pre>
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<ol>
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<li>The <code>feed</code> element is in the <code>http://www.w3.org/2005/Atom</code> namespace.
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<li>The <code>title</code> element is also in the <code>http://www.w3.org/2005/Atom</code> namespace.
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</ol>
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<p>As far as an XML parser is concerned, the previous two XML documents are <em>identical</em>. Namespace + element name = XML identity. Prefixes only exist to refer to namespaces, so the actual prefix name (<code>atom:</code>) is irrelevant. The namespaces match, the element names match, the attributes (or lack of attributes) match, and each element’s text content matches, therefore the XML documents are the same.
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<p>Finally, XML documents can contain <a href=strings.html#one-ring-to-rule-them-all>character encoding information</a> on the first line, before the root element. (If you’re curious how a document can contain information which needs to be known before the document can be parsed, <a href=http://www.w3.org/TR/REC-xml/#sec-guessing-no-ext-info>Section F of the XML specification</a> details how to resolve this Catch-22.)
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<pre class=nd><code><?xml version="1.0" <mark>encoding="utf-8"</mark>?></code></pre>
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<p>And now you know just enough XML to be dangerous!
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<h2 id=xml-structure>The Structure Of An Atom Feed</h2>
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<p>Think of a weblog, or in fact any website with frequently updated content, like <a href=http://www.cnn.com/>CNN.com</a>. The site itself has a title (“CNN.com”), a subtitle (“Breaking News, U.S., World, Weather, Entertainment <i class=baa>&</i> Video News”), a last-updated date (“updated 12:43 p.m. EDT, Sat May 16, 2009”), and a list of articles posted at different times. Each article also has a title, a first-published date (and maybe also a last-updated date, if they published a correction or fixed a typo), and a unique URL.
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<p>The Atom syndication format is designed to capture all of this information in a standard format. My weblog and CNN.com are wildly different in design, scope, and audience, but they both have the same basic structure. CNN.com has a title; my blog has a title. CNN.com publishes articles; I publish articles.
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<p>At the top level is the <i>root element</i>, which every Atom feed shares: the <code>feed</code> element in the <code>http://www.w3.org/2005/Atom</code> namespace.
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<pre class=nd><code>
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<a><feed xmlns="http://www.w3.org/2005/Atom" <span>①</span></a>
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<a> xml:lang="en"> <span>②</span></a></code></pre>
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<ol>
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<li><code>http://www.w3.org/2005/Atom</code> is the Atom namespace.
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<li>Any element can contain an <code>xml:lang</code> attribute, which declares the language of the element and its children. In this case, the <code>xml:lang</code> attribute is declared once on the root element, which means the entire feed is in English.
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</ol>
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<p>An Atom feed contains several pieces of information about the feed itself. These are declared as children of the root-level <code>feed</code> element.
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<pre class=nd><code><feed xmlns="http://www.w3.org/2005/Atom" xml:lang="en">
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<a> <title>dive into mark</title> <span>①</span></a>
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<a> <subtitle>currently between addictions</subtitle> <span>②</span></a>
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<a> <id>tag:diveintomark.org,2001-07-29:/</id> <span>③</span></a>
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<a> <updated>2009-03-27T21:56:07Z</updated> <span>④</span></a>
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<a> <link rel="alternate" type="text/html" href="http://diveintomark.org/"/> <span>⑤</span></a></code></pre>
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<ol>
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<li>The title of this feed is <code>dive into mark</code>.
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<li>The subtitle of this feed is <code>currently between addictions</code>.
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<li>Every feed needs a globally unique identifier. See <a href=http://www.ietf.org/rfc/rfc4151.txt>RFC 4151</a> for how to create one.
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<li>This feed was last updated on March 27, 2009, at 21:56 GMT. This is usually equivalent to the last-modified date of the most recent article.
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<li>Now things start to get interesting. This <code>link</code> element has no text content, but it has three attributes: <code>rel</code>, <code>type</code>, and <code>href</code>. The <code>rel</code> value tells you what kind of link this is; <code>rel="alternate"</code> means that this is a link to an alternate representation of this feed. The <code>type="text/html"</code> attribute means that this is a link to an HTML page. And the link target is given in the <code>href</code> attribute.
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</ol>
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<p>Now we know that this is a feed for a site named “dive into mark“ which is available at <a href=http://diveintomark.org/><code>http://diveintomark.org/</code></a> and was last updated on March 27, 2009.
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<blockquote class=note>
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<p><span>☞</span>Although the order of elements can be relevant in some XML documents, it is not relevant in an Atom feed.
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</blockquote>
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<p>After the feed-level metadata is the list of the most recent articles. An article looks like this:
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<pre class=nd><code><entry>
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<a> <author> <span>①</span></a>
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<name>Mark</name>
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<uri>http://diveintomark.org/</uri>
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</author>
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<a> <title>Dive into history, 2009 edition</title> <span>②</span></a>
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<a> <link rel="alternate" type="text/html" <span>③</span></a>
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href="http://diveintomark.org/archives/2009/03/27/dive-into-history-2009-edition"/>
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<a> <id>tag:diveintomark.org,2009-03-27:/archives/20090327172042</id> <span>④</span></a>
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<a> <updated>2009-03-27T21:56:07Z</updated> <span>⑤</span></a>
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<published>2009-03-27T17:20:42Z</published>
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<a> <category scheme="http://diveintomark.org" term="diveintopython"/> <span>⑥</span></a>
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<category scheme="http://diveintomark.org" term="docbook"/>
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<category scheme="http://diveintomark.org" term="html"/>
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<a> <summary type="html">Putting an entire chapter on one page sounds <span>⑦</span></a>
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bloated, but consider this &amp;mdash; my longest chapter so far
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would be 75 printed pages, and it loads in under 5 seconds&amp;hellip;
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On dialup.</summary>
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<a></entry> <span>⑧</span></a></code></pre>
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<ol>
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<li>The <code>author</code> element tells who wrote this article: some guy named Mark, whom you can find loafing at <code>http://diveintomark.org/</code>. (This is the same as the alternate link in the feed metadata, but it doesn’t have to be. Many weblogs have multiple authors, each with their own personal website.)
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<li>The <code>title</code> element gives the title of the article, “Dive into history, 2009 edition”.
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<li>As with the feed-level alternate link, this <code>link</code> element gives the address of the HTML version of this article.
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<li>Entries, like feeds, need a unique identifier.
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<li>Entries have two dates: a first-published date (<code>published</code>) and a last-modified date (<code>updated</code>).
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<li>Entries can have an arbitrary number of categories. This article is filed under <code>diveintopython</code>, <code>docbook</code>, and <code>html</code>.
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<li>The <code>summary</code> element gives a brief summary of the article. (There is also a <code>content</code> element, not shown here, if you want to include the complete article text in your feed.) This <code>summary</code> element has the Atom-specific <code>type="html"</code> attribute, which specifies that this summary is a snippet of HTML, not plain text. This is important, since it has HTML-specific entities in it (<code>&mdash;</code> and <code>&hellip;</code>) which should be rendered as “—” and “…” rather than displayed directly.
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<li>Finally, the end tag for the <code>entry</code> element, signaling the end of the metadata for this article.
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</ol>
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<h2 id=xml-parse>Parsing XML</h2>
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<p>Python can parse XML documents in several ways. It has traditional <a href=http://en.wikipedia.org/wiki/XML#DOM>DOM</a> and <a href=http://en.wikipedia.org/wiki/Simple_API_for_XML>SAX</a> parsers, but I will focus on a different library called Etree.
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<p class=d>[<a href=examples/feed.xml>download <code>feed.xml</code></a>]
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<pre class=screen>
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<a><samp class=p>>>> </samp><kbd>import xml.etree.ElementTree as etree</kbd> <span>①</span></a>
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<a><samp class=p>>>> </samp><kbd>tree = etree.parse("examples/feed.xml")</kbd> <span>②</span></a>
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<a><samp class=p>>>> </samp><kbd>root = tree.getroot()</kbd> <span>③</span></a>
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<a><samp class=p>>>> </samp><kbd>root</kbd> <span>④</span></a>
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<samp><Element {http://www.w3.org/2005/Atom}feed at cd1eb0></samp></pre>
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<ol>
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<li>The Etree library is part of the Python standard library, in <code>xml.etree.ElementTree</code>.
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<li>The primary entry point for the Etree library is the <code>parse()</code> function, which can take a filename or a file-like object [FIXME xref]. This function parses the entire document at once. If memory is tight, there are ways to parse an XML document incrementally instead.
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<li>The <code>parse()</code> function returns an object which represents the entire document. This is <em>not</em> the root element. To get a reference to the root element, call the <code>getroot()</code> method.
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<li>As expected, the root element is the <code>feed</code> element in the <code>http://www.w3.org/2005/Atom</code> namespace. The string representation of this object reinforces an important point: an XML element is a combination of its namespace and its tag name (also called the <i>local name</i>). Every element in this document is in the Atom namespace, so the root element is represented as <code>{http://www.w3.org/2005/Atom}feed</code>.
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</ol>
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<blockquote class=note>
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<p><span>☞</span>Etree represents XML elements as <code>{<var>namespace</var>}<var>localname</var></code>. You’ll see and use this format in multiple places in the Etree library.
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</blockquote>
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<h3 id=xml-elements>Elements Are Lists</h3>
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<p>In Etree, an element acts like a list. The items of the list are the element’s children.
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<pre class=screen>
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# continued from the previous example
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<samp class=p>>>> </samp><kbd>root.tag</kbd>
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<samp>'{http://www.w3.org/2005/Atom}feed'</samp>
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<samp class=p>>>> </samp><kbd>len(root)</kbd>
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<samp>9</kbd>
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<samp class=p>>>> </samp><kbd>for child in root:</kbd>
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<samp class=p>... </samp><kbd> print(child)</kbd>
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<samp class=p>... </samp>
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<samp><Element {http://www.w3.org/2005/Atom}title at e2b5d0>
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<Element {http://www.w3.org/2005/Atom}subtitle at e2b4e0>
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<Element {http://www.w3.org/2005/Atom}id at e2b6c0>
|
|
<Element {http://www.w3.org/2005/Atom}updated at e2b6f0>
|
|
<Element {http://www.w3.org/2005/Atom}link at e181b0>
|
|
<Element {http://www.w3.org/2005/Atom}link at e2b4b0>
|
|
<Element {http://www.w3.org/2005/Atom}entry at e2b720>
|
|
<Element {http://www.w3.org/2005/Atom}entry at e2b510>
|
|
<Element {http://www.w3.org/2005/Atom}entry at e2b750></samp></pre>
|
|
|
|
<h3 id=xml-attributes>Attributes Are Dictonaries</h3>
|
|
|
|
<p>FIXME
|
|
|
|
<pre class=screen>
|
|
>>> root.attrib
|
|
{'{http://www.w3.org/XML/1998/namespace}lang': 'en'}
|
|
>>> root[4]
|
|
<Element {http://www.w3.org/2005/Atom}link at e181b0>
|
|
>>> root[4].attrib
|
|
{'href': 'http://diveintomark.org/', 'type': 'text/html', 'rel': 'alternate'}
|
|
>>> root[3]
|
|
<Element {http://www.w3.org/2005/Atom}updated at e2b4e0>
|
|
>>> root[3].attrib
|
|
{}
|
|
</pre>
|
|
|
|
<h2 id=xml-find>Searching For Nodes Within An XML Document</h2>
|
|
|
|
<p>FIXME
|
|
|
|
<pre class=screen>
|
|
>>> tree.findall("{http://www.w3.org/2005/Atom}entry")
|
|
[<Element {http://www.w3.org/2005/Atom}entry at e2b4e0>, <Element {http://www.w3.org/2005/Atom}entry at e2b510>, <Element {http://www.w3.org/2005/Atom}entry at e2b540>]
|
|
|
|
>>> feed_links = tree.findall("{http://www.w3.org/2005/Atom}link")
|
|
>>> feed_links
|
|
[<Element {http://www.w3.org/2005/Atom}link at e181b0>, <Element {http://www.w3.org/2005/Atom}link at e2b4b0>]
|
|
>>> feed_links[0].attrib
|
|
{'href': 'http://diveintomark.org/', 'type': 'text/html', 'rel': 'alternate'}
|
|
>>> feed_links[1].attrib
|
|
{'href': 'http://diveintomark.org/feed/', 'type': 'application/atom+xml', 'rel': 'self'}
|
|
|
|
>>> all_links = tree.findall("//{http://www.w3.org/2005/Atom}link")
|
|
>>> all_links
|
|
[<Element {http://www.w3.org/2005/Atom}link at e181b0>, <Element {http://www.w3.org/2005/Atom}link at e2b4b0>, <Element {http://www.w3.org/2005/Atom}link at e2b570>, <Element {http://www.w3.org/2005/Atom}link at e2b480>, <Element {http://www.w3.org/2005/Atom}link at e2b5a0>]
|
|
>>> all_links[0].attrib
|
|
{'href': 'http://diveintomark.org/', 'type': 'text/html', 'rel': 'alternate'}
|
|
>>> all_links[1].attrib
|
|
{'href': 'http://diveintomark.org/feed/', 'type': 'application/atom+xml', 'rel': 'self'}
|
|
>>> all_links[2].attrib
|
|
{'href': 'http://diveintomark.org/archives/2009/03/27/dive-into-history-2009-edition', 'type': 'text/html', 'rel': 'alternate'}
|
|
>>> all_links[3].attrib
|
|
{'href': 'http://diveintomark.org/archives/2009/03/21/accessibility-is-a-harsh-mistress', 'type': 'text/html', 'rel': 'alternate'}
|
|
>>> all_links[4].attrib
|
|
{'href': 'http://diveintomark.org/archives/2008/12/18/give-part-1-container-formats', 'type': 'text/html', 'rel': 'alternate'}
|
|
</pre>
|
|
|
|
<h2 id=xml-lxml>Going Further With lxml</h2>
|
|
|
|
<p>FIXME
|
|
|
|
<pre class=screen>
|
|
>>> from lxml import etree
|
|
.
|
|
. FIXME (show how it's a drop-in replacement for everything we've done so far)
|
|
.
|
|
|
|
from here on out, use lxml.etree explicitly because these functions are specific to lxml
|
|
>>> import lxml.etree
|
|
>>> nsmap = {"atom": "http://www.w3.org/2005/Atom"}
|
|
>>> tree = lxml.etree.parse("examples/feed.xml")
|
|
>>> entries = tree.xpath("//atom:category[@term='accessibility']/..", namespaces=nsmap)
|
|
>>> entries
|
|
[<Element {http://www.w3.org/2005/Atom}entry at e2b630>]
|
|
>>> entry = entries[0]
|
|
>>> entry.xpath("./atom:title/text()", namespaces=nsmap)
|
|
['Accessibility is a harsh mistress']
|
|
</pre>
|
|
|
|
<h3 id=xml-custom-parser>Customizing Your XML Parser</h3>
|
|
|
|
<p>FIXME
|
|
|
|
<pre class=screen>
|
|
>>> import lxml.etree
|
|
>>> parser = lxml.etree.XMLParser(no_network=True, ns_clean=True, recover=True, remove_blank_text=True, remove_comments=True)
|
|
>>> tree = lxml.etree.parse("examples/feed.xml", parser)
|
|
</pre>
|
|
|
|
<h3 id=xml-incremental>Incremental Parsing</h3>
|
|
|
|
<p>FIXME
|
|
|
|
<h2 id=xml-generate>Generating XML</h2>
|
|
|
|
<p>FIXME
|
|
|
|
<pre class=screen>
|
|
>>> import lxml.etree
|
|
>>> new_feed = lxml.etree.Element("{http://www.w3.org/2005/Atom}feed", attrib={"{http://www.w3.org/XML/1998/namespace}lang": "en"})
|
|
>>> print(lxml.etree.tounicode(new_feed))
|
|
<ns0:feed xmlns:ns0="http://www.w3.org/2005/Atom" xml:lang="en"/>
|
|
</pre>
|
|
|
|
<p>FIXME
|
|
|
|
<pre class=screen>
|
|
>>> import lxml.etree
|
|
>>> new_feed = lxml.etree.Element("feed", nsmap=NSMAP)
|
|
>>> print(lxml.etree.tounicode(new_feed))
|
|
<feed xmlns="http://www.w3.org/2005/Atom"/>
|
|
>>> new_feed.set("{http://www.w3.org/XML/1998/namespace}lang", "en")
|
|
>>> print(lxml.etree.tounicode(new_feed))
|
|
<feed xmlns="http://www.w3.org/2005/Atom" xml:lang="en"/>
|
|
</pre>
|
|
|
|
<p>FIXME
|
|
|
|
<pre class=screen>
|
|
>>> title = lxml.etree.SubElement(new_feed, "title", attrib={"type":"html"})
|
|
>>> print(lxml.etree.tounicode(new_feed))
|
|
<feed xmlns="http://www.w3.org/2005/Atom" xml:lang="en"><title type="html"/></feed>
|
|
>>> title.text = "dive into mark"
|
|
>>> print(lxml.etree.tounicode(new_feed))
|
|
<feed xmlns="http://www.w3.org/2005/Atom" xml:lang="en"><title type="html">dive into mark</title></feed>
|
|
>>> print(lxml.etree.tounicode(new_feed, pretty_print=True))
|
|
<feed xmlns="http://www.w3.org/2005/Atom" xml:lang="en">
|
|
<title type="html">dive into mark</title>
|
|
</feed>
|
|
</pre>
|
|
|
|
<h2 id=furtherreading>Further Reading</h2>
|
|
|
|
<ul>
|
|
<li><a href=http://en.wikipedia.org/wiki/XML>XML on Wikipedia.org</a>
|
|
<li><a href=http://docs.python.org/3.0/library/xml.etree.elementtree.html>The ElementTree XML API</a>
|
|
<li><a href=http://effbot.org/zone/element.htm>Elements and Element Trees</a>
|
|
<li><a href=http://effbot.org/zone/element-iterparse.htm>The ElementTree iterparse Function</a>
|
|
<li><a href=http://codespeak.net/lxml/1.3/parsing.html>Parsing XML and HTML with lxml</a>
|
|
<li><a href=http://codespeak.net/lxml/1.3/xpathxslt.html>XPath and XSLT with lxml</a>
|
|
</ul>
|
|
|
|
<p class=c>© 2001–9 <a href=about.html>Mark Pilgrim</a>
|
|
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