在Python中处理XML的简单方法？

Question

对于最近提出的问题,我开始怀疑是否有一种非常简单的方法来处理Python中的XML文档.一种pythonic方式,如果你愿意的话.

如果我举一个例子,也许我可以解释得最好:让我们说以下 - 我认为这是一个很好的例子,说明如何(错误地)在Web服务中使用XML - 是我从http请求到http://www.google的回复的.com/IG/API？天气= 94043

<xml_api_reply version="1">
  <weather module_id="0" tab_id="0" mobile_row="0" mobile_zipped="1" row="0" section="0" >
    <forecast_information>
      <city data="Mountain View, CA"/>
      <postal_code data="94043"/>
      <latitude_e6 data=""/>
      <longitude_e6 data=""/>
      <forecast_date data="2010-06-23"/>
      <current_date_time data="2010-06-24 00:02:54 +0000"/>
      <unit_system data="US"/>
    </forecast_information>
    <current_conditions>
      <condition data="Sunny"/>
      <temp_f data="68"/>
      <temp_c data="20"/>
      <humidity data="Humidity: 61%"/>
      <icon data="/ig/images/weather/sunny.gif"/>
      <wind_condition data="Wind: NW at 19 mph"/>
    </current_conditions>
    ...
    <forecast_conditions>
      <day_of_week data="Sat"/>
      <low data="59"/>
      <high data="75"/>
      <icon data="/ig/images/weather/partly_cloudy.gif"/>
      <condition data="Partly Cloudy"/>
    </forecast_conditions>
  </weather>
</xml_api_reply>

在加载/解析这样的文档之后,我希望能够像访问那样简单地访问信息

>>> xml['xml_api_reply']['weather']['forecast_information']['city'].data
'Mountain View, CA'

要么

>>> xml.xml_api_reply.weather.current_conditions.temp_f['data']
'68'

从我到目前为止看到的情况来看,这似乎ElementTree与我的梦想最接近.但它并不存在,在使用XML时仍然有一些笨手笨脚的事情要做.OTOH,我在想的并不是那么复杂 - 可能只是解析器顶部的薄单板 - 但它可以减少处理XML的烦恼.有这么神奇吗？(如果没有 - 为什么？)

PS.注意我已经尝试过BeautifulSoup了,虽然我喜欢它的方法,但它有空<element/>s的实际问题- 请参阅下面的注释中的示例.

Answer 1

lxml已被提及.您也可以查看lxml.objectify进行一些非常简单的操作.

>>> from lxml import objectify
>>> tree = objectify.fromstring(your_xml)
>>> tree.weather.attrib["module_id"]
'0'
>>> tree.weather.forecast_information.city.attrib["data"]
'Mountain View, CA'
>>> tree.weather.forecast_information.postal_code.attrib["data"]
'94043'

Answer 2

你想要一个薄的贴面？这很容易做饭.尝试使用ElementTree的以下简单包装作为开始:

# geetree.py
import xml.etree.ElementTree as ET

class GeeElem(object):
    """Wrapper around an ElementTree element. a['foo'] gets the
       attribute foo, a.foo gets the first subelement foo."""
    def __init__(self, elem):
        self.etElem = elem

    def __getitem__(self, name):
        res = self._getattr(name)
        if res is None:
            raise AttributeError, "No attribute named '%s'" % name
        return res

    def __getattr__(self, name):
        res = self._getelem(name)
        if res is None:
            raise IndexError, "No element named '%s'" % name
        return res

    def _getelem(self, name):
        res = self.etElem.find(name)
        if res is None:
            return None
        return GeeElem(res)

    def _getattr(self, name):
        return self.etElem.get(name)

class GeeTree(object):
    "Wrapper around an ElementTree."
    def __init__(self, fname):
        self.doc = ET.parse(fname)

    def __getattr__(self, name):
        if self.doc.getroot().tag != name:
            raise IndexError, "No element named '%s'" % name
        return GeeElem(self.doc.getroot())

    def getroot(self):
        return self.doc.getroot()

你调用它:

>>> import geetree
>>> t = geetree.GeeTree('foo.xml')
>>> t.xml_api_reply.weather.forecast_information.city['data']
'Mountain View, CA'
>>> t.xml_api_reply.weather.current_conditions.temp_f['data']
'68'