Python ElementTree 默认命名空间?

2022-01-14 00:00:00 python python-3.x elementtree xml namespaces

问题描述

有没有办法在 python ElementTree 中定义默认/无前缀命名空间?这似乎不起作用...

Is there a way to define the default/unprefixed namespace in python ElementTree? This doesn't seem to work...

ns = {"":"http://maven.apache.org/POM/4.0.0"}
pom = xml.etree.ElementTree.parse("pom.xml")
print(pom.findall("version", ns))

这也不是:

ns = {None:"http://maven.apache.org/POM/4.0.0"}
pom = xml.etree.ElementTree.parse("pom.xml")
print(pom.findall("version", ns))

确实如此，但我必须为每个元素添加前缀:

This does, but then I have to prefix every element:

ns = {"mvn":"http://maven.apache.org/POM/4.0.0"}
pom = xml.etree.ElementTree.parse("pom.xml")
print(pom.findall("mvn:version", ns))

在 OSX 上使用 Python 3.5.

Using Python 3.5 on OSX.

如果答案是否"，您仍然可以获得赏金 :-).我只是想从一个花了很多时间使用它的人那里得到一个明确的不".

if the answer is "no", you can still get the bounty :-). I just want a definitive "no" from someone who's spent a lot of time using it.

解决方案

注意:对于 Python 3.8+，请参阅 这个答案.

NOTE: for Python 3.8+ please see this answer.

没有直接的方法可以透明地处理默认命名空间.正如您已经提到的，为空命名空间分配一个非空名称是一种常见的解决方案:

There is no straight-forward way to handle the default namespaces transparently. Assigning the empty namespace a non-empty name is a common solution, as you've already mentioned:

ns = {"mvn":"http://maven.apache.org/POM/4.0.0"}
pom = xml.etree.ElementTree.parse("pom.xml")
print(pom.findall("mvn:version", ns))

请注意，lxml.etree 不允许显式使用空命名空间.你会得到:

Note that lxml.etree does not allow the use of empty namespaces explicitly. You would get:

ValueError:ElementPath 中不支持空的命名空间前缀

ValueError: empty namespace prefix is not supported in ElementPath

您可以通过 在加载 XML 输入数据时删除默认命名空间定义:

import xml.etree.ElementTree as ET
import re
 
with open("pom.xml") as f:
    xmlstring = f.read()
 
# Remove the default namespace definition (xmlns="http://some/namespace")
xmlstring = re.sub(r'sxmlns="[^"]+"', '', xmlstring, count=1)
 
pom = ET.fromstring(xmlstring) 
print(pom.findall("version"))

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