python - 从 ElementTree 获取更好的解析错误信息

Question

如果我尝试解析损坏的 XML，异常会显示行号。有没有办法显示 XML 上下文？

我想查看损坏部分前后的 xml 标记。

例子:

import xml.etree.ElementTree as ET
tree = ET.fromstring('<a><b></a>')

异常(exception):

Traceback (most recent call last):
  File "tmp/foo.py", line 2, in <module>
    tree = ET.fromstring('<a><b></a>')
  File "/usr/lib/python2.7/xml/etree/ElementTree.py", line 1300, in XML
    parser.feed(text)
  File "/usr/lib/python2.7/xml/etree/ElementTree.py", line 1642, in feed
    self._raiseerror(v)
  File "/usr/lib/python2.7/xml/etree/ElementTree.py", line 1506, in _raiseerror
    raise err
xml.etree.ElementTree.ParseError: mismatched tag: line 1, column 8

像这样的东西会很好:

ParseError:
<a><b></a>
=====^

Answer 1

您可以创建一个辅助函数来执行此操作:

import sys
import io
import itertools as IT
import xml.etree.ElementTree as ET
PY2 = sys.version_info[0] == 2
StringIO = io.BytesIO if PY2 else io.StringIO

def myfromstring(content):
    try:
        tree = ET.fromstring(content)
    except ET.ParseError as err:
        lineno, column = err.position
        line = next(IT.islice(StringIO(content), lineno))
        caret = '{:=>{}}'.format('^', column)
        err.msg = '{}\n{}\n{}'.format(err, line, caret)
        raise 
    return tree

myfromstring('<a><b></a>')

产量

xml.etree.ElementTree.ParseError: mismatched tag: line 1, column 8
<a><b></a>
=======^