:mod:!xml.etree.ElementTree --- The ElementTree XML API

.. module:: xml.etree.ElementTree :synopsis: Implementation of the ElementTree API.

Source code: :source:Lib/xml/etree/ElementTree.py

The :mod:!xml.etree.ElementTree module implements a simple and efficient API for parsing and creating XML data.

.. versionchanged:: 3.3 This module will use a fast implementation whenever available.

.. deprecated:: 3.3 The :mod:!xml.etree.cElementTree module is deprecated.

.. note::

If you need to parse untrusted or unauthenticated data, see :ref:xml-security.

Tutorial

This is a short tutorial for using :mod:!xml.etree.ElementTree (ET in short). The goal is to demonstrate some of the building blocks and basic concepts of the module.

XML tree and elements ^^^^^^^^^^^^^^^^^^^^^

XML is an inherently hierarchical data format, and the most natural way to represent it is with a tree. ET has two classes for this purpose - :class:ElementTree represents the whole XML document as a tree, and :class:Element represents a single node in this tree. Interactions with the whole document (reading and writing to/from files) are usually done on the :class:ElementTree level. Interactions with a single XML element and its sub-elements are done on the :class:Element level.

.. _elementtree-parsing-xml:

Parsing XML ^^^^^^^^^^^

We'll be using the fictive :file:country_data.xml XML document as the sample data for this section:

.. code-block:: xml

We can import this data by reading from a file::

import xml.etree.ElementTree as ET tree = ET.parse('country_data.xml') root = tree.getroot()

Or directly from a string::

root = ET.fromstring(country_data_as_string)

:func:fromstring parses XML from a string directly into an :class:Element, which is the root element of the parsed tree. Other parsing functions may create an :class:ElementTree. Check the documentation to be sure.

As an :class:Element, root has a tag and a dictionary of attributes::

root.tag 'data' root.attrib {}

It also has children nodes over which we can iterate::

for child in root: ... print(child.tag, child.attrib) ... country {'name': 'Liechtenstein'} country {'name': 'Singapore'} country {'name': 'Panama'}

Children are nested, and we can access specific child nodes by index::

root[0][1].text '2008'

.. note::

Not all elements of the XML input will end up as elements of the parsed tree. Currently, this module skips over any XML comments, processing instructions, and document type declarations in the input. Nevertheless, trees built using this module's API rather than parsing from XML text can have comments and processing instructions in them; they will be included when generating XML output. A document type declaration may be accessed by passing a custom :class:TreeBuilder instance to the :class:XMLParser constructor.

.. _elementtree-pull-parsing:

Pull API for non-blocking parsing ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Most parsing functions provided by this module require the whole document to be read at once before returning any result. It is possible to use an :class:XMLParser and feed data into it incrementally, but it is a push API that calls methods on a callback target, which is too low-level and inconvenient for most needs. Sometimes what the user really wants is to be able to parse XML incrementally, without blocking operations, while enjoying the convenience of fully constructed :class:Element objects.

The most powerful tool for doing this is :class:XMLPullParser. It does not require a blocking read to obtain the XML data, and is instead fed with data incrementally with :meth:XMLPullParser.feed calls. To get the parsed XML elements, call :meth:XMLPullParser.read_events. Here is an example::

parser = ET.XMLPullParser(['start', 'end']) parser.feed('<mytag>sometext') list(parser.read_events()) [('start', <Element 'mytag' at 0x7fa66db2be58>)] parser.feed(' more text</mytag>') for event, elem in parser.read_events(): ... print(event) ... print(elem.tag, 'text=', elem.text) ... end mytag text= sometext more text

The obvious use case is applications that operate in a non-blocking fashion where the XML data is being received from a socket or read incrementally from some storage device. In such cases, blocking reads are unacceptable.

Because it's so flexible, :class:XMLPullParser can be inconvenient to use for simpler use-cases. If you don't mind your application blocking on reading XML data but would still like to have incremental parsing capabilities, take a look at :func:iterparse. It can be useful when you're reading a large XML document and don't want to hold it wholly in memory.

Where immediate feedback through events is wanted, calling method :meth:XMLPullParser.flush can help reduce delay; please make sure to study the related security notes.

Finding interesting elements ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

:class:Element has some useful methods that help iterate recursively over all the sub-tree below it (its children, their children, and so on). For example, :meth:Element.iter::

for neighbor in root.iter('neighbor'): ... print(neighbor.attrib) ... {'name': 'Austria', 'direction': 'E'} {'name': 'Switzerland', 'direction': 'W'} {'name': 'Malaysia', 'direction': 'N'} {'name': 'Costa Rica', 'direction': 'W'} {'name': 'Colombia', 'direction': 'E'}

:meth:Element.findall finds only elements with a tag which are direct children of the current element. :meth:Element.find finds the first child with a particular tag, and :attr:Element.text accesses the element's text content. :meth:Element.get accesses the element's attributes::

for country in root.findall('country'): ... rank = country.find('rank').text ... name = country.get('name') ... print(name, rank) ... Liechtenstein 1 Singapore 4 Panama 68

More sophisticated specification of which elements to look for is possible by using :ref:XPath <elementtree-xpath>.

Modifying an XML File ^^^^^^^^^^^^^^^^^^^^^

:class:ElementTree provides a simple way to build XML documents and write them to files. The :meth:ElementTree.write method serves this purpose.

Once created, an :class:Element object may be manipulated by directly changing its fields (such as :attr:Element.text), adding and modifying attributes (:meth:Element.set method), as well as adding new children (for example with :meth:Element.append).

Let's say we want to add one to each country's rank, and add an updated attribute to the rank element::

for rank in root.iter('rank'): ... new_rank = int(rank.text) + 1 ... rank.text = str(new_rank) ... rank.set('updated', 'yes') ... tree.write('output.xml')

Our XML now looks like this:

.. code-block:: xml

We can remove elements using :meth:Element.remove. Let's say we want to remove all countries with a rank higher than 50::

for country in root.findall('country'): ... # using root.findall() to avoid removal during traversal ... rank = int(country.find('rank').text) ... if rank > 50: ... root.remove(country) ... tree.write('output.xml')

Note that concurrent modification while iterating can lead to problems, just like when iterating and modifying Python lists or dicts. Therefore, the example first collects all matching elements with root.findall(), and only then iterates over the list of matches.

Our XML now looks like this:

.. code-block:: xml

Building XML documents ^^^^^^^^^^^^^^^^^^^^^^

The :func:SubElement function also provides a convenient way to create new sub-elements for a given element::

a = ET.Element('a') b = ET.SubElement(a, 'b') c = ET.SubElement(a, 'c') d = ET.SubElement(c, 'd') ET.dump(a) <a><b /><c><d /></c></a>

Parsing XML with Namespaces ^^^^^^^^^^^^^^^^^^^^^^^^^^^

If the XML input has namespaces <https://en.wikipedia.org/wiki/XML_namespace>, tags and attributes with prefixes in the form prefix:sometag get expanded to {uri}sometag where the prefix is replaced by the full URI. Also, if there is a default namespace <https://www.w3.org/TR/xml-names/#defaulting>, that full URI gets prepended to all of the non-prefixed tags.

Here is an XML example that incorporates two namespaces, one with the prefix "fictional" and the other serving as the default namespace:

.. code-block:: xml

<?xml version="1.0"?>
<actors xmlns:fictional="http://characters.example.com"
        xmlns="http://people.example.com">
    <actor>
        <name>John Cleese</name>
        <fictional:character>Lancelot</fictional:character>
        <fictional:character>Archie Leach</fictional:character>
    </actor>
    <actor>
        <name>Eric Idle</name>
        <fictional:character>Sir Robin</fictional:character>
        <fictional:character>Gunther</fictional:character>
        <fictional:character>Commander Clement</fictional:character>
    </actor>
</actors>

One way to search and explore this XML example is to manually add the URI to every tag or attribute in the xpath of a :meth:~Element.find or :meth:~Element.findall::

root = fromstring(xml_text)
for actor in root.findall('{http://people.example.com}actor'):
    name = actor.find('{http://people.example.com}name')
    print(name.text)
    for char in actor.findall('{http://characters.example.com}character'):
        print(' |-->', char.text)

A better way to search the namespaced XML example is to create a dictionary with your own prefixes and use those in the search functions::

ns = {'real_person': 'http://people.example.com',
      'role': 'http://characters.example.com'}

for actor in root.findall('real_person:actor', ns):
    name = actor.find('real_person:name', ns)
    print(name.text)
    for char in actor.findall('role:character', ns):
        print(' |-->', char.text)

These two approaches both output::

John Cleese
 |--> Lancelot
 |--> Archie Leach
Eric Idle
 |--> Sir Robin
 |--> Gunther
 |--> Commander Clement

.. _elementtree-xpath:

XPath support

This module provides limited support for XPath expressions <https://www.w3.org/TR/xpath>_ for locating elements in a tree. The goal is to support a small subset of the abbreviated syntax; a full XPath engine is outside the scope of the module.

Example ^^^^^^^

Here's an example that demonstrates some of the XPath capabilities of the module. We'll be using the countrydata XML document from the :ref:Parsing XML <elementtree-parsing-xml> section::

import xml.etree.ElementTree as ET

root = ET.fromstring(countrydata)

Top-level elements

root.findall(".")

All 'neighbor' grand-children of 'country' children of the top-level

elements

root.findall("./country/neighbor")

Nodes with name='Singapore' that have a 'year' child

root.findall(".//year/..[@name='Singapore']")

'year' nodes that are children of nodes with name='Singapore'

root.findall(".//*[@name='Singapore']/year")

All 'neighbor' nodes that are the second child of their parent

root.findall(".//neighbor[2]")

For XML with namespaces, use the usual qualified {namespace}tag notation::

All dublin-core "title" tags in the document

root.findall(".//{http://purl.org/dc/elements/1.1/}title")

Supported XPath syntax ^^^^^^^^^^^^^^^^^^^^^^

.. tabularcolumns:: |l|L|

+-----------------------+------------------------------------------------------+ | Syntax | Meaning | +=======================+======================================================+ | tag | Selects all child elements with the given tag. | | | For example, spam selects all child elements | | | named spam, and spam/egg selects all | | | grandchildren named egg in all children named | | | spam. {namespace}* selects all tags in the | | | given namespace, {*}spam selects tags named | | | spam in any (or no) namespace, and {}* | | | only selects tags that are not in a namespace. | | | | | | .. versionchanged:: 3.8 | | | Support for star-wildcards was added. | +-----------------------+------------------------------------------------------+ | * | Selects all child elements, including comments and | | | processing instructions. For example, */egg | | | selects all grandchildren named egg. | +-----------------------+------------------------------------------------------+ | . | Selects the current node. This is mostly useful | | | at the beginning of the path, to indicate that it's | | | a relative path. | +-----------------------+------------------------------------------------------+ | // | Selects all subelements, on all levels beneath the | | | current element. For example, .//egg selects | | | all egg elements in the entire tree. | +-----------------------+------------------------------------------------------+ | .. | Selects the parent element. Returns None if the | | | path attempts to reach the ancestors of the start | | | element (the element find was called on). | +-----------------------+------------------------------------------------------+ | [@attrib] | Selects all elements that have the given attribute. | +-----------------------+------------------------------------------------------+ | [@attrib='value'] | Selects all elements for which the given attribute | | | has the given value. The value cannot contain | | | quotes. | +-----------------------+------------------------------------------------------+ | [@attrib!='value']| Selects all elements for which the given attribute | | | does not have the given value. The value cannot | | | contain quotes. | | | | | | .. versionadded:: 3.10 | +-----------------------+------------------------------------------------------+ | [tag] | Selects all elements that have a child named | | | tag. Only immediate children are supported. | +-----------------------+------------------------------------------------------+ | [.='text'] | Selects all elements whose complete text content, | | | including descendants, equals the given text. | | | | | | .. versionadded:: 3.7 | +-----------------------+------------------------------------------------------+ | [.!='text'] | Selects all elements whose complete text content, | | | including descendants, does not equal the given | | | text. | | | | | | .. versionadded:: 3.10 | +-----------------------+------------------------------------------------------+ | [tag='text'] | Selects all elements that have a child named | | | tag whose complete text content, including | | | descendants, equals the given text. | +-----------------------+------------------------------------------------------+ | [tag!='text'] | Selects all elements that have a child named | | | tag whose complete text content, including | | | descendants, does not equal the given text. | | | | | | .. versionadded:: 3.10 | +-----------------------+------------------------------------------------------+ | [position] | Selects all elements that are located at the given | | | position. The position can be either an integer | | | (1 is the first position), the expression last() | | | (for the last position), or a position relative to | | | the last position (e.g. last()-1). | +-----------------------+------------------------------------------------------+

Predicates (expressions within square brackets) must be preceded by a tag name, an asterisk, or another predicate. position predicates must be preceded by a tag name.

Reference

.. _elementtree-functions:

Functions ^^^^^^^^^

.. function:: canonicalize(xml_data=None, *, out=None, from_file=None, **options)

C14N 2.0 <https://www.w3.org/TR/xml-c14n2/>_ transformation function.

Canonicalization is a way to normalise XML output in a way that allows byte-by-byte comparisons and digital signatures. It reduces the freedom that XML serializers have and instead generates a more constrained XML representation. The main restrictions regard the placement of namespace declarations, the ordering of attributes, and ignorable whitespace.

This function takes an XML data string (xml_data) or a file path or file-like object (from_file) as input, converts it to the canonical form, and writes it out using the out file(-like) object, if provided, or returns it as a text string if not. The output file receives text, not bytes. It should therefore be opened in text mode with utf-8 encoding.

Typical uses::

  xml_data = "<root>...</root>"
  print(canonicalize(xml_data))

  with open("c14n_output.xml", mode='w', encoding='utf-8') as out_file:
      canonicalize(xml_data, out=out_file)

  with open("c14n_output.xml", mode='w', encoding='utf-8') as out_file:
      canonicalize(from_file="inputfile.xml", out=out_file)

The configuration options are as follows:

• with_comments: set to true to include comments (default: false)
• strip_text: set to true to strip whitespace before and after text content (default: false)
• rewrite_prefixes: set to true to replace namespace prefixes by "n{number}" (default: false)
• qname_aware_tags: a set of qname aware tag names in which prefixes should be replaced in text content (default: empty)
• qname_aware_attrs: a set of qname aware attribute names in which prefixes should be replaced in text content (default: empty)
• exclude_attrs: a set of attribute names that should not be serialised
• exclude_tags: a set of tag names that should not be serialised

In the option list above, "a set" refers to any collection or iterable of strings, no ordering is expected.

.. versionadded:: 3.8

.. function:: Comment(text=None)

Comment element factory. This factory function creates a special element that will be serialized as an XML comment by the standard serializer. The comment string can be either a bytestring or a Unicode string. text is a string containing the comment string. Returns an element instance representing a comment.

Note that :class:XMLParser skips over comments in the input instead of creating comment objects for them. An :class:ElementTree will only contain comment nodes if they have been inserted into to the tree using one of the :class:Element methods.

.. function:: dump(elem)

Writes an element tree or element structure to sys.stdout. This function should be used for debugging only.

The exact output format is implementation dependent. In this version, it's written as an ordinary XML file.

elem is an element tree or an individual element.

.. versionchanged:: 3.8 The :func:dump function now preserves the attribute order specified by the user.

.. function:: fromstring(text, parser=None)

Parses an XML section from a string constant. Same as :func:XML. text is a string containing XML data. parser is an optional parser instance. If not given, the standard :class:XMLParser parser is used. Returns an :class:Element instance.

.. function:: fromstringlist(sequence, parser=None)

Parses an XML document from a sequence of string fragments. sequence is a list or other sequence containing XML data fragments. parser is an optional parser instance. If not given, the standard :class:XMLParser parser is used. Returns an :class:Element instance.

.. versionadded:: 3.2

.. function:: indent(tree, space=" ", level=0)

Appends whitespace to the subtree to indent the tree visually. This can be used to generate pretty-printed XML output. tree can be an Element or ElementTree. space is the whitespace string that will be inserted for each indentation level, two space characters by default. For indenting partial subtrees inside of an already indented tree, pass the initial indentation level as level.

.. versionadded:: 3.9

.. function:: iselement(element)

Check if an object appears to be a valid element object. element is an element instance. Return True if this is an element object.

.. function:: iterparse(source, events=None, parser=None)

Parses an XML section into an element tree incrementally, and reports what's going on to the user. source is a filename or :term:file object containing XML data. events is a sequence of events to report back. The supported events are the strings "start", "end", "comment", "pi", "start-ns" and "end-ns" (the "ns" events are used to get detailed namespace information). If events is omitted, only "end" events are reported. parser is an optional parser instance. If not given, the standard :class:XMLParser parser is used. parser must be a subclass of :class:XMLParser and can only use the default :class:TreeBuilder as a target. Returns an :term:iterator providing (event, elem) pairs; it has a root attribute that references the root element of the resulting XML tree once source is fully read. The iterator has the :meth:!close method that closes the internal file object if source is a filename.

Note that while :func:iterparse builds the tree incrementally, it issues blocking reads on source (or the file it names). As such, it's unsuitable for applications where blocking reads can't be made. For fully non-blocking parsing, see :class:XMLPullParser.

.. note::

  :func:`iterparse` only guarantees that it has seen the ">" character of a
  starting tag when it emits a "start" event, so the attributes are defined,
  but the contents of the text and tail attributes are undefined at that
  point.  The same applies to the element children; they may or may not be
  present.

  If you need a fully populated element, look for "end" events instead.

.. deprecated:: 3.4 The parser argument.

.. versionchanged:: 3.8 The comment and pi events were added.

.. versionchanged:: 3.13 Added the :meth:!close method.

.. versionchanged:: 3.15 A :exc:ResourceWarning is now emitted if the iterator opened a file and is not explicitly closed.

.. function:: parse(source, parser=None)

Parses an XML section into an element tree. source is a filename or file object containing XML data. parser is an optional parser instance. If not given, the standard :class:XMLParser parser is used. Returns an :class:ElementTree instance.

.. function:: ProcessingInstruction(target, text=None)

PI element factory. This factory function creates a special element that will be serialized as an XML processing instruction. target is a string containing the PI target. text is a string containing the PI contents, if given. Returns an element instance, representing a processing instruction.

Note that :class:XMLParser skips over processing instructions in the input instead of creating PI objects for them. An :class:ElementTree will only contain processing instruction nodes if they have been inserted into to the tree using one of the :class:Element methods.

.. function:: register_namespace(prefix, uri)

Registers a namespace prefix. The registry is global, and any existing mapping for either the given prefix or the namespace URI will be removed. prefix is a namespace prefix. uri is a namespace uri. Tags and attributes in this namespace will be serialized with the given prefix, if at all possible.

.. versionadded:: 3.2

.. function:: SubElement(parent, tag, /, attrib={}, **extra)

Subelement factory. This function creates an element instance, and appends it to an existing element.

The element name, attribute names, and attribute values can be either bytestrings or Unicode strings. parent is the parent element. tag is the subelement name. attrib is an optional dictionary, containing element attributes. extra contains additional attributes, given as keyword arguments. Returns an element instance.

.. versionchanged:: 3.15 attrib can now be a :class:frozendict.

.. versionchanged:: 3.15 parent and tag are now positional-only parameters.

.. function:: tostring(element, encoding="us-ascii", method="xml", *,
xml_declaration=None, default_namespace=None,
short_empty_elements=True)

Generates a string representation of an XML element, including all subelements. element is an :class:Element instance. encoding [1]_ is the output encoding (default is US-ASCII). Use encoding="unicode" to generate a Unicode string (otherwise, a bytestring is generated). method is either "xml", "html" or "text" (default is "xml"). xml_declaration, default_namespace and short_empty_elements has the same meaning as in :meth:ElementTree.write. Returns an (optionally) encoded string containing the XML data.

.. versionchanged:: 3.4 Added the short_empty_elements parameter.

.. versionchanged:: 3.8 Added the xml_declaration and default_namespace parameters.

.. versionchanged:: 3.8 The :func:tostring function now preserves the attribute order specified by the user.

.. function:: tostringlist(element, encoding="us-ascii", method="xml", *,
xml_declaration=None, default_namespace=None,
short_empty_elements=True)

Generates a string representation of an XML element, including all subelements. element is an :class:Element instance. encoding [1]_ is the output encoding (default is US-ASCII). Use encoding="unicode" to generate a Unicode string (otherwise, a bytestring is generated). method is either "xml", "html" or "text" (default is "xml"). xml_declaration, default_namespace and short_empty_elements has the same meaning as in :meth:ElementTree.write. Returns a list of (optionally) encoded strings containing the XML data. It does not guarantee any specific sequence, except that b"".join(tostringlist(element)) == tostring(element).

.. versionadded:: 3.2

.. versionchanged:: 3.4 Added the short_empty_elements parameter.

.. versionchanged:: 3.8 Added the xml_declaration and default_namespace parameters.

.. versionchanged:: 3.8 The :func:tostringlist function now preserves the attribute order specified by the user.

.. function:: XML(text, parser=None)

Parses an XML section from a string constant. This function can be used to embed "XML literals" in Python code. text is a string containing XML data. parser is an optional parser instance. If not given, the standard :class:XMLParser parser is used. Returns an :class:Element instance.

.. function:: XMLID(text, parser=None)

Parses an XML section from a string constant, and also returns a dictionary which maps from element id:s to elements. text is a string containing XML data. parser is an optional parser instance. If not given, the standard :class:XMLParser parser is used. Returns a tuple containing an :class:Element instance and a dictionary.

.. _elementtree-xinclude:

XInclude support

This module provides limited support for XInclude directives <https://www.w3.org/TR/xinclude/>_, via the :mod:xml.etree.ElementInclude helper module. This module can be used to insert subtrees and text strings into element trees, based on information in the tree.

Example ^^^^^^^

Here's an example that demonstrates use of the XInclude module. To include an XML document in the current document, use the {http://www.w3.org/2001/XInclude}include element and set the parse attribute to "xml", and use the href attribute to specify the document to include.

.. code-block:: xml

<?xml version="1.0"?>
<document xmlns:xi="http://www.w3.org/2001/XInclude">
  <xi:include href="source.xml" parse="xml" />
</document>

By default, the href attribute is treated as a file name. You can use custom loaders to override this behaviour. Also note that the standard helper does not support XPointer syntax.

To process this file, load it as usual, and pass the root element to the :mod:!xml.etree.ElementTree module:

.. code-block:: python

from xml.etree import ElementTree, ElementInclude

tree = ElementTree.parse("document.xml") root = tree.getroot()

ElementInclude.include(root)

The ElementInclude module replaces the {http://www.w3.org/2001/XInclude}include element with the root element from the source.xml document. The result might look something like this:

.. code-block:: xml

<document xmlns:xi="http://www.w3.org/2001/XInclude">
  <para>This is a paragraph.</para>
</document>

If the parse attribute is omitted, it defaults to "xml". The href attribute is required.

To include a text document, use the {http://www.w3.org/2001/XInclude}include element, and set the parse attribute to "text":

.. code-block:: xml

<?xml version="1.0"?>
<document xmlns:xi="http://www.w3.org/2001/XInclude">
  Copyright (c) <xi:include href="year.txt" parse="text" />.
</document>

The result might look something like:

.. code-block:: xml

<document xmlns:xi="http://www.w3.org/2001/XInclude">
  Copyright (c) 2003.
</document>

Reference

.. _elementinclude-functions:

Functions ^^^^^^^^^

.. module:: xml.etree.ElementInclude

.. function:: default_loader(href, parse, encoding=None)

Default loader. This default loader reads an included resource from disk. href is a URL. parse is for parse mode either "xml" or "text". encoding is an optional text encoding. If not given, encoding is utf-8. Returns the expanded resource. If the parse mode is "xml", this is an :class:~xml.etree.ElementTree.Element instance. If the parse mode is "text", this is a string. If the loader fails, it can return None or raise an exception.

.. function:: include(elem, loader=None, base_url=None, max_depth=6)

This function expands XInclude directives in-place in tree pointed by elem. elem is either the root :class:~xml.etree.ElementTree.Element or an :class:~xml.etree.ElementTree.ElementTree instance to find such element. loader is an optional resource loader. If omitted, it defaults to :func:default_loader. If given, it should be a callable that implements the same interface as :func:default_loader. base_url is base URL of the original file, to resolve relative include file references. max_depth is the maximum number of recursive inclusions. Limited to reduce the risk of malicious content explosion. Pass None to disable the limitation.

.. versionchanged:: 3.9 Added the base_url and max_depth parameters.

.. _elementtree-element-objects:

Element Objects ^^^^^^^^^^^^^^^

.. module:: xml.etree.ElementTree :noindex: :no-index:

.. class:: Element(tag, /, attrib={}, **extra)

Element class. This class defines the Element interface, and provides a reference implementation of this interface.

The element name, attribute names, and attribute values can be either bytestrings or Unicode strings. tag is the element name. attrib is an optional dictionary, containing element attributes. extra contains additional attributes, given as keyword arguments.

.. versionchanged:: 3.15 attrib can now be a :class:frozendict.

.. versionchanged:: 3.15 tag is now a positional-only parameter.

.. attribute:: tag

  A string identifying what kind of data this element represents (the
  element type, in other words).

.. attribute:: text tail

  These attributes can be used to hold additional data associated with
  the element.  Their values are usually strings but may be any
  application-specific object.  If the element is created from
  an XML file, the *text* attribute holds either the text between
  the element's start tag and its first child or end tag, or ``None``, and
  the *tail* attribute holds either the text between the element's
  end tag and the next tag, or ``None``.  For the XML data

  .. code-block:: xml

     <a><b>1<c>2<d/>3</c></b>4</a>

  the *a* element has ``None`` for both *text* and *tail* attributes,
  the *b* element has *text* ``"1"`` and *tail* ``"4"``,
  the *c* element has *text* ``"2"`` and *tail* ``None``,
  and the *d* element has *text* ``None`` and *tail* ``"3"``.

  To collect the inner text of an element, see :meth:`itertext`, for
  example ``"".join(element.itertext())``.

  Applications may store arbitrary objects in these attributes.

.. attribute:: attrib

  A dictionary containing the element's attributes.  Note that while the
  *attrib* value is always a real mutable Python dictionary, an ElementTree
  implementation may choose to use another internal representation, and
  create the dictionary only if someone asks for it.  To take advantage of
  such implementations, use the dictionary methods below whenever possible.

The following dictionary-like methods work on the element attributes.

.. method:: clear()

  Resets an element.  This function removes all subelements, clears all
  attributes, and sets the text and tail attributes to ``None``.

.. method:: get(key, default=None)

  Gets the element attribute named *key*.

  Returns the attribute value, or *default* if the attribute was not found.

.. method:: items()

  Returns the element attributes as a sequence of (name, value) pairs.  The
  attributes are returned in an arbitrary order.

.. method:: keys()

  Returns the elements attribute names as a list.  The names are returned
  in an arbitrary order.

.. method:: set(key, value)

  Set the attribute *key* on the element to *value*.

The following methods work on the element's children (subelements).

.. method:: append(subelement)

  Adds the element *subelement* to the end of this element's internal list
  of subelements.  Raises :exc:`TypeError` if *subelement* is not an
  :class:`Element`.

.. method:: extend(subelements)

  Appends *subelements* from an iterable of elements.
  Raises :exc:`TypeError` if a subelement is not an :class:`Element`.

  .. versionadded:: 3.2

.. method:: find(match, namespaces=None)

  Finds the first subelement matching *match*.  *match* may be a tag name
  or a :ref:`path <elementtree-xpath>`.  Returns an element instance
  or ``None``.  *namespaces* is an optional mapping from namespace prefix
  to full name.  Pass ``''`` as prefix to move all unprefixed tag names
  in the expression into the given namespace.

.. method:: findall(match, namespaces=None)

  Finds all matching subelements, by tag name or
  :ref:`path <elementtree-xpath>`.  Returns a list containing all matching
  elements in document order.  *namespaces* is an optional mapping from
  namespace prefix to full name.  Pass ``''`` as prefix to move all
  unprefixed tag names in the expression into the given namespace.

.. method:: findtext(match, default=None, namespaces=None)

  Finds text for the first subelement matching *match*.  *match* may be
  a tag name or a :ref:`path <elementtree-xpath>`.  Returns the text content
  of the first matching element, or *default* if no element was found.
  Note that if the matching element has no text content an empty string
  is returned. *namespaces* is an optional mapping from namespace prefix
  to full name.  Pass ``''`` as prefix to move all unprefixed tag names
  in the expression into the given namespace.

.. method:: insert(index, subelement)

  Inserts *subelement* at the given position in this element.  Raises
  :exc:`TypeError` if *subelement* is not an :class:`Element`.

.. method:: iter(tag=None)

  Creates a tree :term:`iterator` with the current element as the root.
  The iterator iterates over this element and all elements below it, in
  document (depth first) order.  If *tag* is not ``None`` or ``'*'``, only
  elements whose tag equals *tag* are returned from the iterator.  If the
  tree structure is modified during iteration, the result is undefined.

  .. versionadded:: 3.2

.. method:: iterfind(match, namespaces=None)

  Finds all matching subelements, by tag name or
  :ref:`path <elementtree-xpath>`.  Returns an iterable yielding all
  matching elements in document order. *namespaces* is an optional mapping
  from namespace prefix to full name.


  .. versionadded:: 3.2

.. method:: itertext()

  Creates a text iterator.  The iterator loops over this element and all
  subelements, in document order, and returns all inner text.

  .. versionadded:: 3.2

.. method:: makeelement(tag, attrib)

  Creates a new element object of the same type as this element.  Do not
  call this method, use the :func:`SubElement` factory function instead.

.. method:: remove(subelement)

  Removes *subelement* from the element.  Unlike the find\* methods this
  method compares elements based on the instance identity, not on tag value
  or contents.

:class:Element objects also support the following sequence type methods for working with subelements: :meth:~object.__delitem__, :meth:~object.__getitem__, :meth:~object.__setitem__, :meth:~object.__len__.

Caution: Elements with no subelements will test as False. In a future release of Python, all elements will test as True regardless of whether subelements exist. Instead, prefer explicit len(elem) or elem is not None tests.::

 element = root.find('foo')

 if not element:  # careful!
     print("element not found, or element has no subelements")

 if element is None:
     print("element not found")

.. versionchanged:: 3.12 Testing the truth value of an Element emits :exc:DeprecationWarning.

Prior to Python 3.8, the serialisation order of the XML attributes of elements was artificially made predictable by sorting the attributes by their name. Based on the now guaranteed ordering of dicts, this arbitrary reordering was removed in Python 3.8 to preserve the order in which attributes were originally parsed or created by user code.

In general, user code should try not to depend on a specific ordering of attributes, given that the XML Information Set <https://www.w3.org/TR/xml-infoset/>_ explicitly excludes the attribute order from conveying information. Code should be prepared to deal with any ordering on input. In cases where deterministic XML output is required, e.g. for cryptographic signing or test data sets, canonical serialisation is available with the :func:canonicalize function.

In cases where canonical output is not applicable but a specific attribute order is still desirable on output, code should aim for creating the attributes directly in the desired order, to avoid perceptual mismatches for readers of the code. In cases where this is difficult to achieve, a recipe like the following can be applied prior to serialisation to enforce an order independently from the Element creation::

 def reorder_attributes(root):
     for el in root.iter():
         attrib = el.attrib
         if len(attrib) > 1:
             # adjust attribute order, e.g. by sorting
             attribs = sorted(attrib.items())
             attrib.clear()
             attrib.update(attribs)

.. _elementtree-elementtree-objects:

ElementTree Objects ^^^^^^^^^^^^^^^^^^^

.. class:: ElementTree(element=None, file=None)

ElementTree wrapper class. This class represents an entire element hierarchy, and adds some extra support for serialization to and from standard XML.

element is the root element. The tree is initialized with the contents of the XML file if given.

.. method:: _setroot(element)

  Replaces the root element for this tree.  This discards the current
  contents of the tree, and replaces it with the given element.  Use with
  care.  *element* is an element instance.

.. method:: find(match, namespaces=None)

  Same as :meth:`Element.find`, starting at the root of the tree.

.. method:: findall(match, namespaces=None)

  Same as :meth:`Element.findall`, starting at the root of the tree.

.. method:: findtext(match, default=None, namespaces=None)

  Same as :meth:`Element.findtext`, starting at the root of the tree.

.. method:: getroot()

  Returns the root element for this tree.

.. method:: iter(tag=None)

  Creates and returns a tree iterator for the root element.  The iterator
  loops over all elements in this tree, in section order.  *tag* is the tag
  to look for (default is to return all elements).

.. method:: iterfind(match, namespaces=None)

  Same as :meth:`Element.iterfind`, starting at the root of the tree.

  .. versionadded:: 3.2

.. method:: parse(source, parser=None)

  Loads an external XML section into this element tree.  *source* is a file
  name or :term:`file object`.  *parser* is an optional parser instance.
  If not given, the standard :class:`XMLParser` parser is used.  Returns the
  section root element.

.. method:: write(file, encoding="us-ascii", xml_declaration=None,
default_namespace=None, method="xml", *,
short_empty_elements=True)

  Writes the element tree to a file, as XML.  *file* is a file name, or a
  :term:`file object` opened for writing.  *encoding* [1]_ is the output
  encoding (default is US-ASCII).
  *xml_declaration* controls if an XML declaration should be added to the
  file.  Use ``False`` for never, ``True`` for always, ``None``
  for only if not US-ASCII or UTF-8 or Unicode (default is ``None``).
  *default_namespace* sets the default XML namespace (for "xmlns").
  *method* is either ``"xml"``, ``"html"`` or ``"text"`` (default is
  ``"xml"``).
  The keyword-only *short_empty_elements* parameter controls the formatting
  of elements that contain no content.  If ``True`` (the default), they are
  emitted as a single self-closed tag, otherwise they are emitted as a pair
  of start/end tags.

  The output is either a string (:class:`str`) or binary (:class:`bytes`).
  This is controlled by the *encoding* argument.  If *encoding* is
  ``"unicode"``, the output is a string; otherwise, it's binary.  Note that
  this may conflict with the type of *file* if it's an open
  :term:`file object`; make sure you do not try to write a string to a
  binary stream and vice versa.

  .. versionchanged:: 3.4
     Added the *short_empty_elements* parameter.

  .. versionchanged:: 3.8
     The :meth:`write` method now preserves the attribute order specified
     by the user.

This is the XML file that is going to be manipulated::

<html>
    <head>
        <title>Example page</title>
    </head>
    <body>
        <p>Moved to <a href="http://example.org/">example.org</a>
        or <a href="http://example.com/">example.com</a>.</p>
    </body>
</html>

Example of changing the attribute "target" of every link in first paragraph::

>>> from xml.etree.ElementTree import ElementTree
>>> tree = ElementTree()
>>> tree.parse("index.xhtml")
<Element 'html' at 0xb77e6fac>
>>> p = tree.find("body/p")     # Finds first occurrence of tag p in body
>>> p
<Element 'p' at 0xb77ec26c>
>>> links = list(p.iter("a"))   # Returns list of all links
>>> links
[<Element 'a' at 0xb77ec2ac>, <Element 'a' at 0xb77ec1cc>]
>>> for i in links:             # Iterates through all found links
...     i.attrib["target"] = "blank"
...
>>> tree.write("output.xhtml")

.. _elementtree-qname-objects:

QName Objects ^^^^^^^^^^^^^

.. class:: QName(text_or_uri, tag=None)

QName wrapper. This can be used to wrap a QName attribute value, in order to get proper namespace handling on output. text_or_uri is a string containing the QName value, in the form {uri}local, or, if the tag argument is given, the URI part of a QName. If tag is given, the first argument is interpreted as a URI, and this argument is interpreted as a local name. :class:QName instances are opaque.

.. _elementtree-treebuilder-objects:

TreeBuilder Objects ^^^^^^^^^^^^^^^^^^^

.. class:: TreeBuilder(element_factory=None, *, comment_factory=None,
pi_factory=None, insert_comments=False, insert_pis=False)

Generic element structure builder. This builder converts a sequence of start, data, end, comment and pi method calls to a well-formed element structure. You can use this class to build an element structure using a custom XML parser, or a parser for some other XML-like format.

element_factory, when given, must be a callable accepting two positional arguments: a tag and a dict of attributes. It is expected to return a new element instance.

The comment_factory and pi_factory functions, when given, should behave like the :func:Comment and :func:ProcessingInstruction functions to create comments and processing instructions. When not given, the default factories will be used. When insert_comments and/or insert_pis is true, comments/pis will be inserted into the tree if they appear within the root element (but not outside of it).

.. method:: close()

  Flushes the builder buffers, and returns the toplevel document
  element.  Returns an :class:`Element` instance.

.. method:: data(data)

  Adds text to the current element.  *data* is a string.  This should be
  either a bytestring, or a Unicode string.

.. method:: end(tag)

  Closes the current element.  *tag* is the element name.  Returns the
  closed element.

.. method:: start(tag, attrs)

  Opens a new element.  *tag* is the element name.  *attrs* is a dictionary
  containing element attributes.  Returns the opened element.

.. method:: comment(text)

  Creates a comment with the given *text*.  If ``insert_comments`` is true,
  this will also add it to the tree.

  .. versionadded:: 3.8

.. method:: pi(target, text)

  Creates a process instruction with the given *target* name and *text*.
  If ``insert_pis`` is true, this will also add it to the tree.

  .. versionadded:: 3.8

In addition, a custom :class:TreeBuilder object can provide the following methods:

.. method:: doctype(name, pubid, system)

  Handles a doctype declaration.  *name* is the doctype name.  *pubid* is
  the public identifier.  *system* is the system identifier.  This method
  does not exist on the default :class:`TreeBuilder` class.

  .. versionadded:: 3.2

.. method:: start_ns(prefix, uri)

  Is called whenever the parser encounters a new namespace declaration,
  before the ``start()`` callback for the opening element that defines it.
  *prefix* is ``''`` for the default namespace and the declared
  namespace prefix name otherwise.  *uri* is the namespace URI.

  .. versionadded:: 3.8

.. method:: end_ns(prefix)

  Is called after the ``end()`` callback of an element that declared
  a namespace prefix mapping, with the name of the *prefix* that went
  out of scope.

  .. versionadded:: 3.8

.. class:: C14NWriterTarget(write, *,
with_comments=False, strip_text=False, rewrite_prefixes=False,
qname_aware_tags=None, qname_aware_attrs=None,
exclude_attrs=None, exclude_tags=None)

A C14N 2.0 <https://www.w3.org/TR/xml-c14n2/>_ writer. Arguments are the same as for the :func:canonicalize function. This class does not build a tree but translates the callback events directly into a serialised form using the write function.

.. versionadded:: 3.8

.. _elementtree-xmlparser-objects:

XMLParser Objects ^^^^^^^^^^^^^^^^^

.. class:: XMLParser(*, target=None, encoding=None)

This class is the low-level building block of the module. It uses :mod:xml.parsers.expat for efficient, event-based parsing of XML. It can be fed XML data incrementally with the :meth:feed method, and parsing events are translated to a push API - by invoking callbacks on the target object. If target is omitted, the standard :class:TreeBuilder is used. If encoding [1]_ is given, the value overrides the encoding specified in the XML file.

.. versionchanged:: 3.8 Parameters are now :ref:keyword-only <keyword-only_parameter>. The html argument is no longer supported.

.. method:: close()

  Finishes feeding data to the parser.  Returns the result of calling the
  ``close()`` method of the *target* passed during construction; by default,
  this is the toplevel document element.

.. method:: feed(data)

  Feeds data to the parser.  *data* is encoded data.

.. method:: flush()

  Triggers parsing of any previously fed unparsed data, which can be
  used to ensure more immediate feedback, in particular with Expat >=2.6.0.
  The implementation of :meth:`flush` temporarily disables reparse deferral
  with Expat (if currently enabled) and triggers a reparse.
  Disabling reparse deferral has security consequences; please see
  :meth:`xml.parsers.expat.xmlparser.SetReparseDeferralEnabled` for details.

  :meth:`!flush`
  has been backported to some prior releases of CPython as a security fix.
  Check for availability using :func:`hasattr` if used in code running
  across a variety of Python versions.

  .. versionadded:: 3.13

:meth:XMLParser.feed calls target's start(tag, attrs_dict) method for each opening tag, its end(tag) method for each closing tag, and data is processed by method data(data). For further supported callback methods, see the :class:TreeBuilder class. :meth:XMLParser.close calls target's method close(). :class:XMLParser can be used not only for building a tree structure. This is an example of counting the maximum depth of an XML file::

>>> from xml.etree.ElementTree import XMLParser
>>> class MaxDepth:                     # The target object of the parser
...     maxDepth = 0
...     depth = 0
...     def start(self, tag, attrib):   # Called for each opening tag.
...         self.depth += 1
...         if self.depth > self.maxDepth:
...             self.maxDepth = self.depth
...     def end(self, tag):             # Called for each closing tag.
...         self.depth -= 1
...     def data(self, data):
...         pass            # We do not need to do anything with data.
...     def close(self):    # Called when all data has been parsed.
...         return self.maxDepth
...
>>> target = MaxDepth()
>>> parser = XMLParser(target=target)
>>> exampleXml = """
... <a>
...   <b>
...   </b>
...   <b>
...     <c>
...       <d>
...       </d>
...     </c>
...   </b>
... </a>"""
>>> parser.feed(exampleXml)
>>> parser.close()
4

.. _elementtree-xmlpullparser-objects:

XMLPullParser Objects ^^^^^^^^^^^^^^^^^^^^^

.. class:: XMLPullParser(events=None)

A pull parser suitable for non-blocking applications. Its input-side API is similar to that of :class:XMLParser, but instead of pushing calls to a callback target, :class:XMLPullParser collects an internal list of parsing events and lets the user read from it. events is a sequence of events to report back. The supported events are the strings "start", "end", "comment", "pi", "start-ns" and "end-ns" (the "ns" events are used to get detailed namespace information). If events is omitted, only "end" events are reported.

.. method:: feed(data)

  Feed the given bytes data to the parser.

.. method:: flush()

  Triggers parsing of any previously fed unparsed data, which can be
  used to ensure more immediate feedback, in particular with Expat >=2.6.0.
  The implementation of :meth:`flush` temporarily disables reparse deferral
  with Expat (if currently enabled) and triggers a reparse.
  Disabling reparse deferral has security consequences; please see
  :meth:`xml.parsers.expat.xmlparser.SetReparseDeferralEnabled` for details.

  :meth:`!flush`
  has been backported to some prior releases of CPython as a security fix.
  Check for availability using :func:`hasattr` if used in code running
  across a variety of Python versions.

  .. versionadded:: 3.13

.. method:: close()

  Signal the parser that the data stream is terminated. Unlike
  :meth:`XMLParser.close`, this method always returns :const:`None`.
  Any events not yet retrieved when the parser is closed can still be
  read with :meth:`read_events`.

.. method:: read_events()

  Return an iterator over the events which have been encountered in the
  data fed to the
  parser.  The iterator yields ``(event, elem)`` pairs, where *event* is a
  string representing the type of event (e.g. ``"end"``) and *elem* is the
  encountered :class:`Element` object, or other context value as follows.

  * ``start``, ``end``: the current Element.
  * ``comment``, ``pi``: the current comment / processing instruction
  * ``start-ns``: a tuple ``(prefix, uri)`` naming the declared namespace
    mapping.
  * ``end-ns``: :const:`None` (this may change in a future version)

  Events provided in a previous call to :meth:`read_events` will not be
  yielded again.  Events are consumed from the internal queue only when
  they are retrieved from the iterator, so multiple readers iterating in
  parallel over iterators obtained from :meth:`read_events` will have
  unpredictable results.

.. note::

  :class:`XMLPullParser` only guarantees that it has seen the ">"
  character of a starting tag when it emits a "start" event, so the
  attributes are defined, but the contents of the text and tail attributes
  are undefined at that point.  The same applies to the element children;
  they may or may not be present.

  If you need a fully populated element, look for "end" events instead.

.. versionadded:: 3.4

.. versionchanged:: 3.8 The comment and pi events were added.

Exceptions ^^^^^^^^^^

.. class:: ParseError

XML parse error, raised by the various parsing methods in this module when parsing fails. The string representation of an instance of this exception will contain a user-friendly error message. In addition, it will have the following attributes available:

.. attribute:: code

  A numeric error code from the expat parser. See the documentation of
  :mod:`xml.parsers.expat` for the list of error codes and their meanings.

.. attribute:: position

  A tuple of *line*, *column* numbers, specifying where the error occurred.

.. rubric:: Footnotes

.. [1] The encoding string included in XML output should conform to the appropriate standards. For example, "UTF-8" is valid, but "UTF8" is not. See https://www.w3.org/TR/2006/REC-xml11-20060816/#NT-EncodingDecl and https://www.iana.org/assignments/character-sets/character-sets.xhtml.