Although there are ElementTree in Python to process xml format, it always feels less convenient than json processing
There are also many libraries that directly convert xml format to json format, such as this xmltodict library
The original webpage related to the library is: https://pypi.python.org/pypi/xmltodict You can view the relevant content
Here is just a record of the implemented mechanism for later viewing.
#!/usr/bin/env python
"Makes working with XML feel like you are working with JSON"
try:
from defusedexpat import pyexpat as expat
except ImportError:
from xml.parsers import expat
from xml.sax.saxutils import XMLGenerator
from xml.sax.xmlreader import AttributesImpl
try: # pragma no cover
from cStringIO import StringIO
except ImportError: # pragma no cover
try:
from StringIO import StringIO
except ImportError:
from io import StringIO
try: # pragma no cover
from collections import OrderedDict
except ImportError: # pragma no cover
try:
from ordereddict import OrderedDict
except ImportError:
OrderedDict = dict
try: # pragma no cover
_base string = base string
except NameError: # pragma no cover
_basestring = str
try: # pragma no cover
_unicode = unicode
except NameError: # pragma no cover
_unicode=str
__author__ = 'Martin Blech'
__version__ = '0.10.2'
__license__ = 'MIT'
class ParsingInterrupted(Exception):
pass
class _DictSAXHandler(object):
def __init__(self,
item_depth=0,
item_callback=lambda *args: True,
xml_attribs=True,
attr_prefix='@',
cdata_key='#text',
force_cdata=False,
cdata_separator='',
postprocessor=None,
dict_constructor=OrderedDict,
strip_whitespace=True,
namespace_separator=':',
namespaces=None,
force_list=None):
self.path = []
self.stack = []
self.data = []
self.item = None
self.item_depth = item_depth
self.xml_attribs = xml_attribs
self.item_callback = item_callback
self.attr_prefix = attr_prefix
self.cdata_key = cdata_key
self.force_cdata = force_cdata
self.cdata_separator = cdata_separator
self.postprocessor = postprocessor
self.dict_constructor = dict_constructor
self.strip_whitespace = strip_whitespace
self.namespace_separator = namespace_separator
self.namespaces = namespaces
self.force_list = force_list
def _build_name(self, full_name):
if not self.namespaces:
return full_name
i = full_name.rfind(self.namespace_separator)
if i == -1:
return full_name
namespace, name = full_name[:i], full_name[i+1:]
short_namespace = self.namespaces.get(namespace, namespace)
if not short_namespace:
return name
else:
return self.namespace_separator.join((short_namespace, name))
def _attrs_to_dict(self, attrs):
if isinstance(attrs, dict):
return attrs
return self.dict_constructor(zip(attrs[0::2], attrs[1::2]))
def startElement(self, full_name, attrs):
name = self._build_name(full_name)
attrs = self._attrs_to_dict(attrs)
self.path.append((name, attrs or None))
if len(self.path) > self.item_depth:
self.stack.append((self.item, self.data))
if self.xml_attribs:
attr_entries = []
for key, value in attrs.items():
key = self.attr_prefix+self._build_name(key)
if self.postprocessor:
entry = self.postprocessor(self.path, key, value)
else:
entry = (key, value)
if entry:
attr_entries.append(entry)
attrs = self.dict_constructor(attr_entries)
else:
attrs = None
self.item = attrs or None
self.data = []
def endElement(self, full_name):
name = self._build_name(full_name)
if len(self.path) == self.item_depth:
item = self.item
if item is None:
item = (None if not self.data
else self.cdata_separator.join(self.data))
should_continue = self.item_callback(self.path, item)
if not should_continue:
raise ParsingInterrupted()
if len(self.stack):
data = (None if not self.data
else self.cdata_separator.join(self.data))
item = self.item
self.item, self.data = self.stack.pop()
if self.strip_whitespace and data:
data = data.strip() or None
if data and self.force_cdata and item is None:
item = self.dict_constructor()
if item is not None:
if data:
self.push_data(item, self.cdata_key, data)
self.item = self.push_data(self.item, name, item)
else:
self.item = self.push_data(self.item, name, data)
else:
self.item = None
self.data = []
self.path.pop()
def characters(self, data):
if not self.data:
self.data = [data]
else:
self.data.append(data)
def push_data(self, item, key, data):
if self.postprocessor is not None:
result = self.postprocessor(self.path, key, data)
if result is None:
return item
key, data = result
if item is None:
item = self.dict_constructor()
try:
value = item[key]
if isinstance(value, list):
value.append(data)
else:
item[key] = [value, data]
except KeyError:
if self._should_force_list(key, data):
item[key] = [data]
else:
item[key] = data
return item
def _should_force_list(self, key, value):
if not self.force_list:
return False
try:
return key in self.force_list
except TypeError:
return self.force_list(self.path[:-1], key, value)
def parse(xml_input, encoding=None, expat=expat, process_namespaces=False,
namespace_separator=':', **kwargs):
"""Parse the given XML input and convert it into a dictionary.
`xml_input` can either be a `string` or a file-like object.
If `xml_attribs` is `True`, element attributes are put in the dictionary
among regular child elements, using `@` as a prefix to avoid collisions. If
set to `False`, they are just ignored.
Simple example::
>>> import xmltodict
>>> doc = xmltodict.parse(\"\"\"
... <a prop="x">
... <b>1</b>
... <b>2</b>
... </a>
... \"\"\")
>>> doc['a']['@prop']
u'x'
>>> doc['a']['b']
[u'1', u'2']
If `item_depth` is `0`, the function returns a dictionary for the root
element (default behavior). Otherwise, it calls `item_callback` every time
an item at the specified depth is found and returns `None` in the end
(streaming mode).
The callback function receives two parameters: the `path` from the document
root to the item (name-attribs pairs), and the `item` (dict). If the
callback's return value is false-ish, parsing will be stopped with the
:class:`ParsingInterrupted` exception.
Streaming example::
>>> def handle(path, item):
... print 'path:%s item:%s' % (path, item)
... return True
...
>>> xmltodict.parse(\"\"\"
... <a prop="x">
... <b>1</b>
... <b>2</b>
... </a>\"\"\", item_depth=2, item_callback=handle)
path:[(u'a', {u'prop': u'x'}), (u'b', None)] item:1
path:[(u'a', {u'prop': u'x'}), (u'b', None)] item:2
The optional argument `postprocessor` is a function that takes `path`,
`key` and `value` as positional arguments and returns a new `(key, value)`
pair where both `key` and `value` may have changed. Usage example::
>>> def postprocessor(path, key, value):
... try:
... return key + ':int', int(value)
... except (ValueError, TypeError):
... return key, value
>>> xmltodict.parse('<a><b>1</b><b>2</b><b>x</b></a>',
... postprocessor=postprocessor)
OrderedDict([(u'a', OrderedDict([(u'b:int', [1, 2]), (u'b', u'x')]))])
You can pass an alternate version of `expat` (such as `defusedexpat`) by
using the `expat` parameter. E.g:
>>> import defusedexpat
>>> xmltodict.parse('<a>hello</a>', expat=defusedexpat.pyexpat)
OrderedDict([(u'a', u'hello')])
You can use the force_list argument to force lists to be created even
when there is only a single child of a given level of hierarchy. The
force_list argument is a tuple of keys. If the key for a given level
of hierarchy is in the force_list argument, that level of hierarchy
will have a list as a child (even if there is only one sub-element).
The index_keys operation takes precendence over this. This is applied
after any user-supplied postprocessor has already run.
For example, given this input:
<servers>
<server>
<name>host1</name>
<os>Linux</os>
<interfaces>
<interface>
<name>em0</name>
<ip_address>10.0.0.1</ip_address>
</interface>
</interfaces>
</server>
</servers>
If called with force_list=('interface',), it will produce
this dictionary:
{'servers':
{'server':
{'name': 'host1',
'os': 'Linux'},
'interfaces':
{'interface':
[ {'name': 'em0', 'ip_address': '10.0.0.1' } ] } } }
`force_list` can also be a callable that receives `path`, `key` and
`value`. This is helpful in cases where the logic that decides whether
a list should be forced is more complex.
"""
handler = _DictSAXHandler(namespace_separator=namespace_separator,
**kwargs)
if isinstance(xml_input, _unicode):
if not encoding:
encoding = 'utf-8'
xml_input = xml_input.encode(encoding)
if not process_namespaces:
namespace_separator = None
parser = expat.ParserCreate(
encoding,
namespace_separator
)
try:
parser.ordered_attributes = True
except AttributeError:
# Jython's expat does not support ordered_attributes
pass
parser.StartElementHandler = handler.startElement
parser.EndElementHandler = handler.endElement
parser.CharacterDataHandler = handler.characters
parser.buffer_text = True
try:
parser.ParseFile(xml_input)
except (TypeError, AttributeError):
parser.Parse(xml_input, True)
return handler.item
def _emit(key, value, content_handler,
attr_prefix='@',
cdata_key='#text',
depth=0,
preprocessor=None,
pretty=False,
newl = '\ n',
indent='\t',
full_document=True):
if preprocessor is not None:
result = preprocessor(key, value)
if result is None:
return
key, value = result
if (not hasattr(value, '__iter__')
or isinstance(value, _basestring)
or isinstance(value, dict)):
value = [value]
for index, v in enumerate(value):
if full_document and depth == 0 and index > 0:
raise ValueError('document with multiple roots')
if v is None:
v = OrderedDict()
elif not isinstance(v, dict):
v = _unicode(v)
if isinstance(v, _basestring):
v = OrderedDict(((cdata_key, v),))
cdata = None
attrs = OrderedDict()
children = []
for ik, iv in v.items ():
if ik == cdata_key:
cdata = iv
continue
if ik.startswith(attr_prefix):
if not isinstance(iv, _unicode):
iv = _unicode (iv)
attrs[ik[len(attr_prefix):]] = iv
continue
children.append((i,iv))
if pretty:
content_handler.ignorableWhitespace(depth * indent)
content_handler.startElement(key, AttributesImpl(attrs))
if pretty and children:
content_handler.ignorableWhitespace(newl)
for child_key, child_value in children:
_emit(child_key, child_value, content_handler,
attr_prefix, cdata_key, depth+1, preprocessor,
pretty, newl, indent)
if cdata is not None:
content_handler.characters(cdata)
if pretty and children:
content_handler.ignorableWhitespace(depth * indent)
content_handler.endElement (key)
if pretty and depth:
content_handler.ignorableWhitespace(newl)
def unparse(input_dict, output=None, encoding='utf-8', full_document=True,
**quargs):
"""Emit an XML document for the given `input_dict` (reverse of `parse`).
The resulting XML document is returned as a string, but if `output` (a
file-like object) is specified, it is written there instead.
Dictionary keys prefixed with `attr_prefix` (default=`'@'`) are interpreted
as XML node attributes, whereas keys equal to `cdata_key`
(default=`'#text'`) are treated as character data.
The `pretty` parameter (default=`False`) enables pretty-printing. In this
mode, lines are terminated with `'\n'` and indented with `'\t'`, but this
can be customized with the `newl` and `indent` parameters.
"""
if full_document and len(input_dict) != 1:
raise ValueError('Document must have exactly one root.')
must_return = False
if output is None:
output = StringIO()
must_return = True
content_handler = XMLGenerator(output, encoding)
if full_document:
content_handler.startDocument ()
for key, value in input_dict.items():
_emit(key, value, content_handler, full_document=full_document,
**kwargs)
if full_document:
content_handler.endDocument()
if must_return:
value = output.getvalue()
try: # pragma no cover
value = value.decode(encoding)
except AttributeError: # pragma no cover
pass
return value
if __name__ == '__main__': # pragma: no cover
import sys
import marshal
try:
stdin = sys.stdin.buffer
stdout = sys.stdout.buffer
except AttributeError:
stdin = sys.stdin
stdout = sys.stdout
(item_depth,) = sys.argv[1:]
item_depth = int(item_depth)
def handle_item(path, item):
marshal.dump((path, item), stdout)
return True
try:
root = parse(stdin,
item_depth=item_depth,
item_callback=handle_item,
dict_constructor=dict)
if item_depth == 0:
handle_item([], root)
except KeyboardInterrupt:
pass