ElementTree and unicode

问题:

I have this char in an xml file:

<data>
  <products>
      <color>fumè</color>
  </product>
</data>

I try to generate an instance of ElementTree with the following code:

string_data = open('file.xml')
x = ElementTree.fromstring(unicode(string_data.encode('utf-8')))

and I get the following error:

UnicodeEncodeError: 'ascii' codec can't encode character u'\xe8' in position 185: ordinal not in range(128)

(NOTE: The position is not exact, I sampled the xml from a larger one).

How to solve it? Thanks

回答1:

You do not need to decode XML for ElementTree to work. XML carries it's own encoding information (defaulting to UTF-8) and ElementTree does the work for you, outputting unicode:

>>> data = '''\
... <data>
...   <products>
...       <color>fumè</color>
...   </products>
... </data>
... '''
>>> x = ElementTree.fromstring(data)
>>> x[0][0].text
u'fum\xe8'

If your data is contained in a file(like) object, just pass the filename or file object directly to the ElementTree.parse() function:

x = ElementTree.parse('file.xml')

回答2:

Might you have stumbled upon this problem while using Requests (HTTP for Humans), response.text decodes the response by default, you can use response.content to get the undecoded data, so ElementTree can decode it itself. Just remember to use the correct encoding.

More info: http://docs.python-requests.org/en/latest/user/quickstart/#response-content

回答3:

You need to decode utf-8 strings into a unicode object. So

string_data.encode('utf-8')

should be

string_data.decode('utf-8')

assuming string_data is actually an utf-8 string.

So to summarize: To get an utf-8 string from a unicode object you encode the unicode (using the utf-8 encoding), and to turn a string to a unicode object you decode the string using the respective encoding.

For more details on the concepts I suggest reading The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (not Python specific).

回答4:

Have you tried using the parse function, instead of opening the file... (which BTW would require a .read() after it for the .fromstring() to work...)

import xml.etree.ElementTree as ET

tree = ET.parse('file.xml')
root = tree.getroot()
# etc...

回答5:

Function open() does not return a string. Instead use open('file.xml').read().

回答6:

The most likely your file is not UTF-8. è character can be from some other encoding, latin-1 for example.