如何用lxml中的文本替换元素? [英] How can one replace an element with text in lxml?

问题描述

使用lxml的ElementTree API实现，很容易从XML文档中完全删除给定的元素，但是我看不到一种用某些文本一致地替换元素的简便方法.例如，给出以下输入:

It's easy to completely remove a given element from an XML document with lxml's implementation of the ElementTree API, but I can't see an easy way of consistently replacing an element with some text. For example, given the following input:

input = '''<everything>
<m>Some text before <r/></m>
<m><r/> and some text after.</m>
<m><r/></m>
<m>Text before <r/> and after</m>
<m><b/> Text after a sibling <r/> Text before a sibling<b/></m>
</everything>
'''

...您可以使用以下命令轻松删除每个<r>元素:

... you could easily remove every <r> element with:

from lxml import etree
f = etree.fromstring(data)
for r in f.xpath('//r'):
    r.getparent().remove(r)
print etree.tostring(f, pretty_print=True)

但是，您将如何用文本替换每个元素以获取输出:

However, how would you go about replacing each element with text, to get the output:

<everything>
<m>Some text before DELETED</m>
<m>DELETED and some text after.</m>
<m>DELETED</m>
<m>Text before DELETED and after</m>
<m><b/>Text after a sibling DELETED Text before a sibling<b/></m>
</everything>

在我看来，因为ElementTree API通过每个元素的.text和.tail属性而不是树中的节点来处理文本，所以这意味着您必须根据是否要处理许多不同的情况进行处理元素是否具有同级元素，现有元素是否具有.tail属性，依此类推.我是否错过了一些简单的方法?

It seems to me that because the ElementTree API deals with text via the .text and .tail attributes of each element rather than nodes in the tree, this means you have to deal with a lot of different cases depending on whether the element has sibling elements or not, whether the existing element had a .tail attribute, and so on. Have I missed some easy way of doing this?

推荐答案

我认为unutbu的XSLT解决方案可能是实现目标的正确方法.

I think that unutbu's XSLT solution is probably the correct way to achieve your goal.

但是，通过修改<r/>标签的尾部然后使用etree.strip_elements，这是一种有点棘手的方法.

However, here's a somewhat hacky way to achieve it, by modifying the tails of <r/> tags and then using etree.strip_elements.

from lxml import etree

data = '''<everything>
<m>Some text before <r/></m>
<m><r/> and some text after.</m>
<m><r/></m>
<m>Text before <r/> and after</m>
<m><b/> Text after a sibling <r/> Text before a sibling<b/></m>
</everything>
'''

f = etree.fromstring(data)
for r in f.xpath('//r'):
  r.tail = 'DELETED' + r.tail if r.tail else 'DELETED'

etree.strip_elements(f,'r',with_tail=False)

print etree.tostring(f,pretty_print=True)

给你:

<everything>
<m>Some text before DELETED</m>
<m>DELETED and some text after.</m>
<m>DELETED</m>
<m>Text before DELETED and after</m>
<m><b/> Text after a sibling DELETED Text before a sibling<b/></m>
</everything>

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