: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`.
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 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.
We'll be using the fictive :file:`country_data.xml` XML document as the sample data for this section:
<?xml version="1.0"?>
<data>
<country name="Liechtenstein">
<rank>1</rank>
<year>2008</year>
<gdppc>141100</gdppc>
<neighbor name="Austria" direction="E"/>
<neighbor name="Switzerland" direction="W"/>
</country>
<country name="Singapore">
<rank>4</rank>
<year>2011</year>
<gdppc>59900</gdppc>
<neighbor name="Malaysia" direction="N"/>
</country>
<country name="Panama">
<rank>68</rank>
<year>2011</year>
<gdppc>13600</gdppc>
<neighbor name="Costa Rica" direction="W"/>
<neighbor name="Colombia" direction="E"/>
</country>
</data>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.
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.
: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>`.
: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:
<?xml version="1.0"?>
<data>
<country name="Liechtenstein">
<rank updated="yes">2</rank>
<year>2008</year>
<gdppc>141100</gdppc>
<neighbor name="Austria" direction="E"/>
<neighbor name="Switzerland" direction="W"/>
</country>
<country name="Singapore">
<rank updated="yes">5</rank>
<year>2011</year>
<gdppc>59900</gdppc>
<neighbor name="Malaysia" direction="N"/>
</country>
<country name="Panama">
<rank updated="yes">69</rank>
<year>2011</year>
<gdppc>13600</gdppc>
<neighbor name="Costa Rica" direction="W"/>
<neighbor name="Colombia" direction="E"/>
</country>
</data>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:
<?xml version="1.0"?>
<data>
<country name="Liechtenstein">
<rank updated="yes">2</rank>
<year>2008</year>
<gdppc>141100</gdppc>
<neighbor name="Austria" direction="E"/>
<neighbor name="Switzerland" direction="W"/>
</country>
<country name="Singapore">
<rank updated="yes">5</rank>
<year>2011</year>
<gdppc>59900</gdppc>
<neighbor name="Malaysia" direction="N"/>
</country>
</data>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>
If the XML input has namespaces, 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,
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:
<?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
When serializing XML that contains a default namespace, ElementTree will by
default add a generated prefix (such as ns0) instead of preserving the
default namespace. For example:
>>> root = ET.fromstring("<doc xmlns='http://example.com'><p>text</p></doc>")
>>> print(ET.tostring(root, encoding='unicode'))
<ns0:doc xmlns:ns0="http://example.com"><ns0:p>text</ns0:p></ns0:doc>
To preserve the default namespace during serialization, use the default_namespace parameter with :func:`tostring` or :meth:`ElementTree.write`:
>>> root = ET.fromstring("<doc xmlns='http://example.com'><p>text</p></doc>")
>>> print(ET.tostring(root, encoding='unicode', default_namespace='http://example.com'))
<doc xmlns="http://example.com"><p>text</p></doc>
.. versionadded:: 3.8 The *default_namespace* parameter.
This module provides limited support for XPath expressions 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.
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")
.. tabularcolumns:: |l|L|
| Syntax | Meaning |
|---|---|
tag |
Selects all child elements with the given tag.
For example, .. 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 .. versionadded:: 3.7 |
[.!='text'] |
Selects all elements whose complete text content,
including descendants, does not equal the given
.. 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
.. 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.
.. 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:: next
*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.
This module provides limited support for XInclude directives, 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.
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.
<?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:
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:
<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":
<?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:
<document xmlns:xi="http://www.w3.org/2001/XInclude">
Copyright (c) 2003.
</document>.. 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.
.. module:: xml.etree.ElementTree :noindex: :no-index:
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")
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.
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
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.
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.
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. |