如何使lxml的迭代解析忽略无效的XML字符？

Question

我有一个包含无效字符的XML。LXML的XMLParser会对这些无效字符抛出异常，但当我使用recover=True选项创建XMLParser时，它会忽略错误字符并正常工作。

我的问题是如何为lxml的iterparse函数设置类似的标志？

繁殖：

断开的XML（/tmp/z.XML）：

<?xml version="1.0" encoding="utf-8"?>
<items>
    <item>
        <B>Bad characters:</B>
    </item>
</items>

注意：字符串“Bad characters:”后面有两个ASCII字符#31（0x1F），我无法在这里复制粘贴。

XMLParser的解析错误：

fd = open('/tmp/z.xml')
parser = etree.XMLParser()
tree   = etree.parse(fd, parser)

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "lxml.etree.pyx", line 2576, in lxml.etree.parse (src/lxml/lxml.etree.c:22796)
  File "parser.pxi", line 1488, in lxml.etree._parseDocument (src/lxml/lxml.etree.c:60390)
  File "parser.pxi", line 1518, in lxml.etree._parseFilelikeDocument (src/lxml/lxml.etree.c:60687)
  File "parser.pxi", line 1401, in lxml.etree._parseDocFromFilelike (src/lxml/lxml.etree.c:59658)
  File "parser.pxi", line 991, in lxml.etree._BaseParser._parseDocFromFilelike (src/lxml/lxml.etree.c:57303)
  File "parser.pxi", line 538, in lxml.etree._ParserContext._handleParseResultDoc (src/lxml/lxml.etree.c:53512)
  File "parser.pxi", line 624, in lxml.etree._handleParseResult (src/lxml/lxml.etree.c:54372)
  File "parser.pxi", line 564, in lxml.etree._raiseParseError (src/lxml/lxml.etree.c:53770)
lxml.etree.XMLSyntaxError: PCDATA invalid Char value 31, line 4, column 21

要忽略错误字符，我将recover=True设置为OK：

import lxml.etree as etree
fd = open('/tmp/z.xml')
parser = etree.XMLParser(recover=True)
tree   = etree.parse(fd, parser)
etree.tostring(tree)

# OUTPUT:
<items>\n\t<item>\n\t\t<B>Bad characters:</B>\n\t</item>\n</items>'

使用iterparse时，我再次遇到相同的错误，但如何使其忽略坏字符？

fd = open('/tmp/z.xml')
it = etree.iterparse(fd, events=("start", "end"))
for e in it: print e
...
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "iterparse.pxi", line 498, in lxml.etree.iterparse.__next__ (src/lxml/lxml.etree.c:73245)
  File "parser.pxi", line 564, in lxml.etree._raiseParseError (src/lxml/lxml.etree.c:53770)
lxml.etree.XMLSyntaxError: PCDATA invalid Char value 31, line 4, column 21

Answer 1

iterparse还接受recover参数：

it = etree.iterparse(fd, events=("start", "end"), recover=True)

（文档：lxml iterparse）