19.12. xml.etree.ElementTree
— The ElementTree XML API¶
Source code: Lib/xml/etree/ElementTree.py
The Element
type is a flexible container object, designed to store
hierarchical data structures in memory. The type can be described as a cross
between a list and a dictionary.
Each element has a number of properties associated with it:
- a tag which is a string identifying what kind of data this element represents (the element type, in other words).
- a number of attributes, stored in a Python dictionary.
- a text string.
- an optional tail string.
- a number of child elements, stored in a Python sequence
To create an element instance, use the Element
constructor or the
SubElement()
factory function.
The ElementTree
class can be used to wrap an element structure, and
convert it from and to XML.
A C implementation of this API is available as xml.etree.cElementTree
.
See http://effbot.org/zone/element-index.htm for tutorials and links to other docs. Fredrik Lundh’s page is also the location of the development version of the xml.etree.ElementTree.
Changed in version 3.2:
Changed in version 3.2: The ElementTree API is updated to 1.3. For more information, see Introducing ElementTree 1.3.
19.12.1. Functions¶
-
xml.etree.ElementTree.
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.
-
xml.etree.ElementTree.
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.
-
xml.etree.ElementTree.
fromstring
(text)¶ Parses an XML section from a string constant. Same as
XML()
. text is a string containing XML data. Returns anElement
instance.
-
xml.etree.ElementTree.
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
XMLParser
parser is used. Returns anElement
instance.New in version 3.2:
New in version 3.2.
-
xml.etree.ElementTree.
iselement
(element)¶ Checks if an object appears to be a valid element object. element is an element instance. Returns a true value if this is an element object.
-
xml.etree.ElementTree.
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 file object containing XML data. events is a list of events to report back. If omitted, only “end” events are reported. parser is an optional parser instance. If not given, the standard
XMLParser
parser is used. Returns an iterator providing(event, elem)
pairs.Note
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.
-
xml.etree.ElementTree.
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
XMLParser
parser is used. Returns anElementTree
instance.
-
xml.etree.ElementTree.
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.
-
xml.etree.ElementTree.
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.
New in version 3.2:
New in version 3.2.
-
xml.etree.ElementTree.
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.
-
xml.etree.ElementTree.
tostring
(element, encoding="us-ascii", method="xml")¶ Generates a string representation of an XML element, including all subelements. element is an
Element
instance. encoding [1] is the output encoding (default is US-ASCII). Useencoding="unicode"
to generate a Unicode string. method is either"xml"
,"html"
or"text"
(default is"xml"
). Returns an (optionally) encoded string containing the XML data.
-
xml.etree.ElementTree.
tostringlist
(element, encoding="us-ascii", method="xml")¶ Generates a string representation of an XML element, including all subelements. element is an
Element
instance. encoding [1] is the output encoding (default is US-ASCII). Useencoding="unicode"
to generate a Unicode string. method is either"xml"
,"html"
or"text"
(default is"xml"
). Returns a list of (optionally) encoded strings containing the XML data. It does not guarantee any specific sequence, except that"".join(tostringlist(element)) == tostring(element)
.New in version 3.2:
New in version 3.2.
-
xml.etree.ElementTree.
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
XMLParser
parser is used. Returns anElement
instance.
-
xml.etree.ElementTree.
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
XMLParser
parser is used. Returns a tuple containing anElement
instance and a dictionary.
19.12.2. Element Objects¶
-
class
xml.etree.ElementTree.
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.
-
tag
¶ A string identifying what kind of data this element represents (the element type, in other words).
-
text
¶ The text attribute can be used to hold additional data associated with the element. As the name implies this attribute is usually a string but may be any application-specific object. If the element is created from an XML file the attribute will contain any text found between the element tags.
-
tail
¶ The tail attribute can be used to hold additional data associated with the element. This attribute is usually a string but may be any application-specific object. If the element is created from an XML file the attribute will contain any text found after the element’s end tag and before the next tag.
-
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.
-
clear
()¶ Resets an element. This function removes all subelements, clears all attributes, and sets the text and tail attributes to None.
-
get
(key, default=None)¶ Gets the element attribute named key.
Returns the attribute value, or default if the attribute was not found.
-
items
()¶ Returns the element attributes as a sequence of (name, value) pairs. The attributes are returned in an arbitrary order.
-
keys
()¶ Returns the elements attribute names as a list. The names are returned in an arbitrary order.
-
set
(key, value)¶ Set the attribute key on the element to value.
The following methods work on the element’s children (subelements).
-
append
(subelement)¶ Adds the element subelement to the end of this elements internal list of subelements.
-
extend
(subelements)¶ Appends subelements from a sequence object with zero or more elements. Raises
AssertionError
if a subelement is not a valid object.New in version 3.2:
New in version 3.2.
-
-
find
(match)¶ Finds the first subelement matching match. match may be a tag name or path. Returns an element instance or
None
.
-
findall
(match)¶ Finds all matching subelements, by tag name or path. Returns a list containing all matching elements in document order.
-
findtext
(match, default=None)¶ Finds text for the first subelement matching match. match may be a tag name or path. 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.
-
getchildren
()¶ Deprecated since version 3.2:
Deprecated since version 3.2: Use
list(elem)
or iteration.
-
getiterator
(tag=None)¶ Deprecated since version 3.2:
Deprecated since version 3.2: Use method
Element.iter()
instead.