本文介绍了从 lxml 中选择属性值的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着跟版网的小编来一起学习吧！
问题描述
我想使用 xpath 表达式来获取属性的值.
I want to use an xpath expression to get the value of an attribute.
我希望以下工作
from lxml import etree
for customer in etree.parse('file.xml').getroot().findall('BOB'):
print customer.find('./@NAME')
但这给出了一个错误:
Traceback (most recent call last):
File "bob.py", line 22, in <module>
print customer.find('./@ID')
File "lxml.etree.pyx", line 1409, in lxml.etree._Element.find (src/lxml/lxml.etree.c:39972)
File "/usr/local/lib/python2.7/dist-packages/lxml/_elementpath.py", line 272, in find
it = iterfind(elem, path, namespaces)
File "/usr/local/lib/python2.7/dist-packages/lxml/_elementpath.py", line 262, in iterfind
selector = _build_path_iterator(path, namespaces)
File "/usr/local/lib/python2.7/dist-packages/lxml/_elementpath.py", line 246, in _build_path_iterator
selector.append(ops[token[0]](_next, token))
KeyError: '@'
我期望这会起作用吗?
推荐答案
find 和 findall 只实现 XPath 的一个子集.它们的存在是为了提供与其他 ElementTree 实现(如 ElementTree 和 cElementTree)的兼容性.
find and findall only implement a subset of XPath. Their presence is meant to provide compatibility with other ElementTree implementations (like ElementTree and cElementTree).
相比之下，xpath 方法提供对 XPath 1.0 的完全访问:
The xpath method, in contrast, provides full access to XPath 1.0:
print customer.xpath('./@NAME')[0]
但是，您可以改为使用 get:
However, you could instead use get:
print customer.get('NAME')
或属性:
print customer.attrib['NAME']
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