Cannot write XML file with default namespace [duplicate]

问题:

This question already has an answer here:

• Saving XML files using ElementTree 4 answers

I'm writing a Python script to update Visual Studio project files. They look like this:

       ... 

The following code reads and then writes the file:

import xml.etree.ElementTree as ET  tree = ET.parse(projectFile) root = tree.getroot() tree.write(projectFile,            xml_declaration = True,            encoding = 'utf-8',            method = 'xml',            default_namespace = "http://schemas.microsoft.com/developer/msbuild/2003") 

Python throws an error at the last line, saying:

ValueError: cannot use non-qualified names with default_namespace option 

This is surprising since I'm just reading and writing, with no editing in between. Visual Studio refuses to load XML files without a default namespace, so omitting it is not optional.

Why does this error occur? Suggestions or alternatives welcome.

回答1:

This is a duplicate to Saving XML files using ElementTree

The solution is to define your default namespace BEFORE parsing the project file.

ET.register_namespace('',"http://schemas.microsoft.com/developer/msbuild/2003") 

Then write out your file as

tree.write(projectFile,            xml_declaration = True,            encoding = 'utf-8',            method = 'xml') 

You have successfully round-tripped your file. And avoided the creation of ns0 tags everywhere.

回答2:

I think that lxml does a better job handling namespaces. It aims for an ElementTree-like interface but uses xmllib2 underneath.

>>> import lxml.etree >>> doc=lxml.etree.fromstring(""" ...  ...    ...    ... """)  >>> print lxml.etree.tostring(doc, xml_declaration=True, encoding='utf-8', method='xml', pretty_print=True) 

回答3:

This was the closest answer I could find to my problem. Putting the:

ET.register_namespace('',"http://schemas.microsoft.com/developer/msbuild/2003") 

just before the parsing of my file did not work.

You need to find the specific namespace the xml file you are loading is using. To do that, I printed out the Element of the ET tree node's tag which gave me my namespace to use and the tag name, copy that namespace into:

ET.register_namespace('',"XXXXX YOUR NAMESPACEXXXXXX") 

before you start parsing your file then that should remove all the namespaces when you write.

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