使用 Python 在 ElementTree 中添加兄弟元素

Question

用XML如

<a>
  <b>
  </b>
</a>

我需要添加类似的兄弟姐妹

<a>
  <b>
  </b>
  <b'>
  </b'>
</a>

ElementTree 有添加兄弟节点的功能吗？ 如果没有，我想我需要一个函数来获取父节点并添加子节点，我该怎么做？

Answer 1

在标准库的版本中，您不能直接访问父级，您必须从父级向下工作，或者自己跟踪父子关系，请阅读these tips（来自库的作者）。

如果您使用lxml，则有getparent() 方法（您也有getnext() 和getprevious()），但更方便的是：有addnext() 和addprevious()。

因此，根据您使用的 ElementTree 实现选择其中一种解决方案（或者甚至切换您的实现）

Answer 2

Python 标准库中包含的默认 ElementTree 实现没有获取父节点的方法。

但是，如果您可以使用lxml's etree 实现，那么有一个getparent() 方法。

Answer 3

手头有什么：

import re

def sibling(bal,text):
    print 'bal ==' + bal + '\n' # + '\n\n' + s

    def aux(match):
        # match.group(4) is '/' or None    
        return ("%s%s<%s'/>%s" % match.group(1,2,3,6) if match.group(4)
                else "%s%s<%s'>%s'>%s" % match.group(1,2,3,5,6))

    return re.sub('('
                  '(^\s*)<(' + bal + ')(?: [^/>]+)?'  # 2 and 3
                  '(?:(/)|>(?:.*?)((?:(?:\n|\r\n?)\\2)?</\\3))' # 4 and 5
                  '>(\n|\r\n?|\Z)' # 6
                  ')',
                  aux, text, flags = re.MULTILINE|re.DOTALL)


ch = """\
<a>
  <b>
  </b>
</a>
"""

dh = """\
<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:dd="http://example.com/ns/1.0" xml:lang="en-US">
<entry>
    <dd:country_code>USA</dd:country_code>
    <content type="html">Hello World!</content>
    <OTF>
      <FECS state="disabled" version="2.2.0.0">
        <BackEndCompatibility major="2.2" state="disabled">
            <BackEnd state="disabled" version="2.2.0.0"/>
            <Forth type="ziwi">d,;%er*dkj@jkber-uyr</Forth>
        </BackEndCompatibility>
      </FECS>
    </OTF>
</entry>
"""

print sibling('a',ch)
print '------------------------------------------------------'
print sibling('b',ch)
print '------------------------------------------------------'

for x in ('entry','dd:country_code','content','OTF','FECS',
          'BackEndCompatibility','BackEnd','Forth'):
    print sibling(x,dh)
    print '------------------------------------------------------'

结果：

bal ==a

<a>
  <b>
  </b>
</a>
<a'>
</a'>

------------------------------------------------------
bal ==b

<a>
  <b>
  </b>
  <b'>
  </b'>
</a>

------------------------------------------------------
bal ==entry

<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:dd="http://example.com/ns/1.0" xml:lang="en-US">
<entry>
    <dd:country_code>USA</dd:country_code>
    <content type="html">Hello World!</content>
    <OTF>
      <FECS state="disabled" version="2.2.0.0">
        <BackEndCompatibility major="2.2" state="disabled">
            <BackEnd state="disabled" version="2.2.0.0"/>
            <Forth type="ziwi">d,;%er*dkj@jkber-uyr</Forth>
        </BackEndCompatibility>
      </FECS>
    </OTF>
</entry>
<entry'>
</entry'>

------------------------------------------------------
bal ==dd:country_code

<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:dd="http://example.com/ns/1.0" xml:lang="en-US">
<entry>
    <dd:country_code>USA</dd:country_code>
    <dd:country_code'></dd:country_code'>
    <content type="html">Hello World!</content>
    <OTF>
      <FECS state="disabled" version="2.2.0.0">
        <BackEndCompatibility major="2.2" state="disabled">
            <BackEnd state="disabled" version="2.2.0.0"/>
            <Forth type="ziwi">d,;%er*dkj@jkber-uyr</Forth>
        </BackEndCompatibility>
      </FECS>
    </OTF>
</entry>

------------------------------------------------------
bal ==content

<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:dd="http://example.com/ns/1.0" xml:lang="en-US">
<entry>
    <dd:country_code>USA</dd:country_code>
    <content type="html">Hello World!</content>
    <content'></content'>
    <OTF>
      <FECS state="disabled" version="2.2.0.0">
        <BackEndCompatibility major="2.2" state="disabled">
            <BackEnd state="disabled" version="2.2.0.0"/>
            <Forth type="ziwi">d,;%er*dkj@jkber-uyr</Forth>
        </BackEndCompatibility>
      </FECS>
    </OTF>
</entry>

------------------------------------------------------
bal ==OTF

<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:dd="http://example.com/ns/1.0" xml:lang="en-US">
<entry>
    <dd:country_code>USA</dd:country_code>
    <content type="html">Hello World!</content>
    <OTF>
      <FECS state="disabled" version="2.2.0.0">
        <BackEndCompatibility major="2.2" state="disabled">
            <BackEnd state="disabled" version="2.2.0.0"/>
            <Forth type="ziwi">d,;%er*dkj@jkber-uyr</Forth>
        </BackEndCompatibility>
      </FECS>
    </OTF>
    <OTF'>
    </OTF'>
</entry>

------------------------------------------------------
bal ==FECS

<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:dd="http://example.com/ns/1.0" xml:lang="en-US">
<entry>
    <dd:country_code>USA</dd:country_code>
    <content type="html">Hello World!</content>
    <OTF>
      <FECS state="disabled" version="2.2.0.0">
        <BackEndCompatibility major="2.2" state="disabled">
            <BackEnd state="disabled" version="2.2.0.0"/>
            <Forth type="ziwi">d,;%er*dkj@jkber-uyr</Forth>
        </BackEndCompatibility>
      </FECS>
      <FECS'>
      </FECS'>
    </OTF>
</entry>

------------------------------------------------------
bal ==BackEndCompatibility

<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:dd="http://example.com/ns/1.0" xml:lang="en-US">
<entry>
    <dd:country_code>USA</dd:country_code>
    <content type="html">Hello World!</content>
    <OTF>
      <FECS state="disabled" version="2.2.0.0">
        <BackEndCompatibility major="2.2" state="disabled">
            <BackEnd state="disabled" version="2.2.0.0"/>
            <Forth type="ziwi">d,;%er*dkj@jkber-uyr</Forth>
        </BackEndCompatibility>
        <BackEndCompatibility'>
        </BackEndCompatibility'>
      </FECS>
    </OTF>
</entry>

------------------------------------------------------
bal ==BackEnd

<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:dd="http://example.com/ns/1.0" xml:lang="en-US">
<entry>
    <dd:country_code>USA</dd:country_code>
    <content type="html">Hello World!</content>
    <OTF>
      <FECS state="disabled" version="2.2.0.0">
        <BackEndCompatibility major="2.2" state="disabled">
            <BackEnd state="disabled" version="2.2.0.0"/>
            <BackEnd'/>
            <Forth type="ziwi">d,;%er*dkj@jkber-uyr</Forth>
        </BackEndCompatibility>
      </FECS>
    </OTF>
</entry>

------------------------------------------------------
bal ==Forth

<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:dd="http://example.com/ns/1.0" xml:lang="en-US">
<entry>
    <dd:country_code>USA</dd:country_code>
    <content type="html">Hello World!</content>
    <OTF>
      <FECS state="disabled" version="2.2.0.0">
        <BackEndCompatibility major="2.2" state="disabled">
            <BackEnd state="disabled" version="2.2.0.0"/>
            <Forth type="ziwi">d,;%er*dkj@jkber-uyr</Forth>
            <Forth'></Forth'>
        </BackEndCompatibility>
      </FECS>
    </OTF>
</entry>

------------------------------------------------------

它适用于'a' 和

"""\
<a>
  <b>
  </b>
</a>
"""

但不是

"""\
<a>
  <b>
  </b>
</a>"""