``xml.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('Some data some more data')
The ``parse()`` function can take either a filename or an open file
xml.dom.minidom.parse(filename_or_file[, parser[, bufsize]])
Return a ``Document`` from the given input. *filename_or_file* may
be either a file name, or a file-like object. *parser*, if given,
must be a SAX2 parser object. This function will change the
document handler of the parser and activate namespace support;
other parser configuration (like setting an entity resolver) must
have been done in advance.
If you have XML in a string, you can use the ``parseString()``
Return a ``Document`` that represents the *string*. This method
creates a ``StringIO`` object for the string and passes that on to
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.')
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("Some data")
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:
``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.
Document Object Model (DOM) Level 1 Specification
The W3C recommendation for the DOM supported by
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``.
Break internal references within the DOM so that it will be garbage
collected on versions of Python without cyclic GC. Even when
cyclic GC is available, using this can make large amounts of memory
available sooner, so calling this on DOM objects as soon as they
are no longer needed is good practice. This only needs to be
called on the ``Document`` object, but may be called on child nodes
to discard children of that node.
Node.writexml(writer[, indent=""[, addindent=""[, newl=""[, encoding=""]]]])
Write XML to the writer object. The writer should have a
``write()`` method which matches that of the file object interface.
The *indent* parameter is the indentation of the current node. The
*addindent* parameter is the incremental indentation to use for
subnodes of the current one. The *newl* parameter specifies the
string to use to terminate newlines.
Changed in version 2.1: The optional keyword parameters *indent*,
*addindent*, and *newl* were added to support pretty output.
Changed in version 2.3: For the ``Document`` node, an additional
keyword argument *encoding* can be used to specify the encoding
field of the XML header.
Return the XML that the DOM represents as a string.
With no argument, the XML header does not specify an encoding, and
the result is Unicode string if the default encoding cannot
represent all characters in the document. Encoding this string in
an encoding other than UTF-8 is likely incorrect, since UTF-8 is
the default encoding of XML.
With an explicit *encoding*  argument, the result is a byte
string in the specified encoding. It is recommended that this
argument is always specified. To avoid ``UnicodeError`` exceptions
in case of unrepresentable text data, the encoding argument should
be specified as "utf-8".
Changed in version 2.3: the *encoding* argument was introduced; see
Node.toprettyxml([indent=""[, newl=""[, encoding=""]]])
Return a pretty-printed version of the document. *indent* specifies
the indentation string and defaults to a tabulator; *newl*
specifies the string emitted at the end of each line and defaults
New in version 2.1.
Changed in version 2.3: the encoding argument was introduced; see
The following standard DOM methods have special considerations with
Although this method was present in the version of
``xml.dom.minidom`` packaged with Python 2.0, it was seriously
broken. This has been corrected for subsequent releases.
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.
document = """\
This is a demo
Of a program for processing slides
Another demo slide
It is important
To have more than
dom = xml.dom.minidom.parseString(document)
rc = ""
for node in nodelist:
if node.nodeType == node.TEXT_NODE:
rc = rc + node.data
slides = slideshow.getElementsByTagName("slide")
for slide in slides:
print "%s" % getText(title.childNodes)
%s" % getText(title.childNodes)
for point in points:
print "%s" % getText(point.childNodes)
for slide in slides:
title = slide.getElementsByTagName("title")
%s" % getText(title.childNodes)
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:
* Interfaces are accessed through instance objects. Applications
should not instantiate the classes themselves; they should use the
creator functions available on the ``Document`` object. Derived
interfaces support all operations (and attributes) from the base
interfaces, plus any new operations.
* Operations are used as methods. Since the DOM uses only ``in``
parameters, the arguments are passed in normal order (from left to
right). There are no optional arguments. ``void`` operations return
* IDL attributes map to instance attributes. For compatibility with
the OMG IDL language mapping for Python, an attribute ``foo`` can
also be accessed through accessor methods ``_get_foo()`` and
``_set_foo()``. ``readonly`` attributes must not be changed; this
is not enforced at runtime.
* The types ``short int``, ``unsigned int``, ``unsigned long long``,
and ``boolean`` all map to Python integer objects.
* The type ``DOMString`` maps to Python strings. ``xml.dom.minidom``
supports either byte or Unicode strings, but will normally produce
Unicode strings. Values of type ``DOMString`` may also be ``None``
where allowed to have the IDL ``null`` value by the DOM
specification from the W3C.
* ``const`` declarations map to variables in their respective scope
(e.g. ``xml.dom.minidom.Node.PROCESSING_INSTRUCTION_NODE``); they
must not be changed.
* ``DOMException`` is currently not supported in ``xml.dom.minidom``.
Instead, ``xml.dom.minidom`` uses standard Python exceptions such as
``TypeError`` and ``AttributeError``.
* ``NodeList`` objects are implemented using Python's built-in list
type. Starting with Python 2.2, these objects provide the interface
defined in the DOM specification, but with earlier versions of
Python they do not support the official API. They are, however,
much more "Pythonic" than the interface defined in the W3C
The following interfaces have no implementation in
* ``DocumentType`` (added in Python 2.1)
* ``DOMImplementation`` (added in Python 2.1)
Most of these reflect information in the XML document that is not of
general utility to most DOM users.
-[ Footnotes ]-
 The encoding string included in XML output should conform to the
appropriate standards. For example, "UTF-8" is valid, but "UTF8"
is not. See http://www.w3.org/TR/2006/REC-xml11-20060816/#NT-
EncodingDecl and http://www.iana.org/assignments/character-sets .