Navigationxml.dom.minidom — Lightweight DOM implementation¶New in version 2.0. xml.dom.minidom is a light-weight implementation of the Document Object Model interface. It is intended to be simpler than the full DOM and also significantly smaller. DOM applications typically start by parsing some XML into a DOM. With xml.dom.minidom, this is done through the parse functions: from xml.dom.minidom import parse, parseString
dom1 = parse('c:\\temp\\mydata.xml') # parse an XML file by name
datasource = open('c:\\temp\\mydata.xml')
dom2 = parse(datasource) # parse an open file
dom3 = parseString('<myxml>Some data<empty/> some more data</myxml>')
The parse() function can take either a filename or an open file object.
If you have XML in a string, you can use the parseString() function instead:
Both functions return a Document object representing the content of the document. What the parse() and parseString() functions do is connect an XML parser with a “DOM builder” that can accept parse events from any SAX parser and convert them into a DOM tree. The name of the functions are perhaps misleading, but are easy to grasp when learning the interfaces. The parsing of the document will be completed before these functions return; it’s simply that these functions do not provide a parser implementation themselves. You can also create a Document by calling a method on a “DOM Implementation” object. You can get this object either by calling the getDOMImplementation() function in the xml.dom package or the xml.dom.minidom module. Using the implementation from the xml.dom.minidom module will always return a Document instance from the minidom implementation, while the version from xml.dom may provide an alternate implementation (this is likely if you have the PyXML package installed). Once you have a Document, you can add child nodes to it to populate the DOM: from xml.dom.minidom import getDOMImplementation
impl = getDOMImplementation()
newdoc = impl.createDocument(None, "some_tag", None)
top_element = newdoc.documentElement
text = newdoc.createTextNode('Some textual content.')
top_element.appendChild(text)
Once you have a DOM document object, you can access the parts of your XML document through its properties and methods. These properties are defined in the DOM specification. The main property of the document object is the documentElement property. It gives you the main element in the XML document: the one that holds all others. Here is an example program: dom3 = parseString("<myxml>Some data</myxml>")
assert dom3.documentElement.tagName == "myxml"
When you are finished with a DOM, you should clean it up. This is necessary because some versions of Python do not support garbage collection of objects that refer to each other in a cycle. Until this restriction is removed from all versions of Python, it is safest to write your code as if cycles would not be cleaned up. The way to clean up a DOM is to call its unlink() method: dom1.unlink()
dom2.unlink()
dom3.unlink()
unlink() is a xml.dom.minidom-specific extension to the DOM API. After calling unlink() on a node, the node and its descendants are essentially useless. See also
DOM Objects¶The definition of the DOM API for Python is given as part of the xml.dom module documentation. This section lists the differences between the API and xml.dom.minidom.
The following standard DOM methods have special considerations with xml.dom.minidom:
DOM Example¶This example program is a fairly realistic example of a simple program. In this particular case, we do not take much advantage of the flexibility of the DOM. import xml.dom.minidom
document = """\
<slideshow>
<title>Demo slideshow</title>
<slide><title>Slide title</title>
<point>This is a demo</point>
<point>Of a program for processing slides</point>
</slide>
<slide><title>Another demo slide</title>
<point>It is important</point>
<point>To have more than</point>
<point>one slide</point>
</slide>
</slideshow>
"""
dom = xml.dom.minidom.parseString(document)
def getText(nodelist):
rc = ""
for node in nodelist:
if node.nodeType == node.TEXT_NODE:
rc = rc + node.data
return rc
def handleSlideshow(slideshow):
print "<html>"
handleSlideshowTitle(slideshow.getElementsByTagName("title")[0])
slides = slideshow.getElementsByTagName("slide")
handleToc(slides)
handleSlides(slides)
print "</html>"
def handleSlides(slides):
for slide in slides:
handleSlide(slide)
def handleSlide(slide):
handleSlideTitle(slide.getElementsByTagName("title")[0])
handlePoints(slide.getElementsByTagName("point"))
def handleSlideshowTitle(title):
print "<title>%s</title>" % getText(title.childNodes)
def handleSlideTitle(title):
print "<h2>%s</h2>" % getText(title.childNodes)
def handlePoints(points):
print "<ul>"
for point in points:
handlePoint(point)
print "</ul>"
def handlePoint(point):
print "<li>%s</li>" % getText(point.childNodes)
def handleToc(slides):
for slide in slides:
title = slide.getElementsByTagName("title")[0]
print "<p>%s</p>" % getText(title.childNodes)
handleSlideshow(dom)
minidom and the DOM standard¶The xml.dom.minidom module is essentially a DOM 1.0-compatible DOM with some DOM 2 features (primarily namespace features). Usage of the DOM interface in Python is straight-forward. The following mapping rules apply:
The following interfaces have no implementation in xml.dom.minidom:
Most of these reflect information in the XML document that is not of general utility to most DOM users. Footnotes
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