mirror of https://github.com/python/cpython
Issue #15586: add some examples to ElementTree documentation. Patch by Daniel Ellis.
This commit is contained in:
Eli Bendersky
parent
2fbe7622e2
commit
0f4e934174
|
|
@ -35,10 +35,11 @@ and its sub-elements are done on the :class:`Element` level.
|
|||
Parsing XML
|
||||
^^^^^^^^^^^
|
||||
|
||||
We'll be using the following XML document contained in a Python string as the
|
||||
sample data for this section::
|
||||
We'll be using the following XML document as the sample data for this section:
|
||||
|
||||
countrydata = r'''<?xml version="1.0"?>
|
||||
.. code-block:: xml
|
||||
|
||||
<?xml version="1.0"?>
|
||||
<data>
|
||||
<country name="Liechtenshtein">
|
||||
<rank>1</rank>
|
||||
|
|
@ -61,18 +62,20 @@ sample data for this section::
|
|||
<neighbor name="Colombia" direction="E"/>
|
||||
</country>
|
||||
</data>
|
||||
'''
|
||||
|
||||
First, import the module and parse the 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()
|
||||
|
||||
root = ET.fromstring(countrydata)
|
||||
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`. Make sure to check the documentation to be
|
||||
sure.
|
||||
create an :class:`ElementTree`. Check the documentation to be sure.
|
||||
|
||||
As an :class:`Element`, ``root`` has a tag and a dictionary of attributes::
|
||||
|
||||
|
|
@ -111,13 +114,27 @@ the sub-tree below it (its children, their children, and so on). For example,
|
|||
{'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 :meth:`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)
|
||||
...
|
||||
Liechtenshtein 1
|
||||
Singapore 4
|
||||
Panama 68
|
||||
|
||||
More sophisticated specification of which elements to look for is possible by
|
||||
using :ref:`XPath <elementtree-xpath>`.
|
||||
|
||||
Building XML documents
|
||||
^^^^^^^^^^^^^^^^^^^^^^
|
||||
Modifying an XML File
|
||||
^^^^^^^^^^^^^^^^^^^^^
|
||||
|
||||
``ET`` provides a simple way to build XML documents and write them to files.
|
||||
: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
|
||||
|
|
@ -125,6 +142,78 @@ 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
|
||||
|
||||
<?xml version="1.0"?>
|
||||
<data>
|
||||
<country name="Liechtenshtein">
|
||||
<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'):
|
||||
... rank = int(country.find('rank').text)
|
||||
... if rank > 50:
|
||||
... root.remove(country)
|
||||
...
|
||||
... tree.write('output.xml')
|
||||
|
||||
Our XML now looks like this:
|
||||
|
||||
.. code-block:: xml
|
||||
|
||||
<?xml version="1.0"?>
|
||||
<data>
|
||||
<country name="Liechtenshtein">
|
||||
<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>
|
||||
|
||||
Building XML documents
|
||||
^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
||||
The :func:`SubElement` function also provides a convenient way to create new
|
||||
sub-elements for a given element::
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue