将xml文件与不带外部库的嵌套元素合并

Question

我正在尝试使用Python将多个XML文件合并在一起，而不使用外部库。XML文件具有嵌套元素。

示例文件1:

<root>
  <element1>textA</element1>
  <elements>
    <nested1>text now</nested1>
  </elements>
</root>

示例文件2:

<root>
  <element2>textB</element2>
  <elements>
    <nested1>text after</nested1>
    <nested2>new text</nested2>
  </elements>
</root>

我想要的：

<root>
  <element1>textA</element1>    
  <element2>textB</element2>  
  <elements>
    <nested1>text after</nested1>
    <nested2>new text</nested2>
  </elements>  
</root>  

我尝试过的：

来自this answer。

from xml.etree import ElementTree as et
def combine_xml(files):
    first = None
    for filename in files:
        data = et.parse(filename).getroot()
        if first is None:
            first = data
        else:
            first.extend(data)
    if first is not None:
        return et.tostring(first)

我得到的：

<root>
  <element1>textA</element1>
  <elements>
    <nested1>text now</nested1>
  </elements>
  <element2>textB</element2>
  <elements>
    <nested1>text after</nested1>
    <nested2>new text</nested2>
  </elements>
</root>

我希望你能理解我的问题。我正在寻找一个合适的解决方案，任何指导都会很好。

为了澄清这个问题，使用我现有的解决方案，嵌套元素不会合并。

Answer 1

您发布的代码所做的是组合所有元素，而不管是否已经存在具有相同标记的元素。因此，您需要遍历这些元素，并以您认为合适的方式手动检查和组合它们，因为这不是处理XML文件的标准方法。我无法比代码更好地解释它，所以这里，或多或少地评论了一下：

from xml.etree import ElementTree as et

class XMLCombiner(object):
    def __init__(self, filenames):
        assert len(filenames) > 0, 'No filenames!'
        # save all the roots, in order, to be processed later
        self.roots = [et.parse(f).getroot() for f in filenames]

    def combine(self):
        for r in self.roots[1:]:
            # combine each element with the first one, and update that
            self.combine_element(self.roots[0], r)
        # return the string representation
        return et.tostring(self.roots[0])

    def combine_element(self, one, other):
        """
        This function recursively updates either the text or the children
        of an element if another element is found in `one`, or adds it
        from `other` if not found.
        """
        # Create a mapping from tag name to element, as that's what we are fltering with
        mapping = {el.tag: el for el in one}
        for el in other:
            if len(el) == 0:
                # Not nested
                try:
                    # Update the text
                    mapping[el.tag].text = el.text
                except KeyError:
                    # An element with this name is not in the mapping
                    mapping[el.tag] = el
                    # Add it
                    one.append(el)
            else:
                try:
                    # Recursively process the element, and update it in the same way
                    self.combine_element(mapping[el.tag], el)
                except KeyError:
                    # Not in the mapping
                    mapping[el.tag] = el
                    # Just add it
                    one.append(el)

if __name__ == '__main__':
    r = XMLCombiner(('sample1.xml', 'sample2.xml')).combine()
    print '-'*20
    print r

Answer 2

谢谢，但我的问题是通过考虑属性来合并。这是我的补丁后的代码：

    import sys
    from xml.etree import ElementTree as et


    class hashabledict(dict):
        def __hash__(self):
            return hash(tuple(sorted(self.items())))


    class XMLCombiner(object):
        def __init__(self, filenames):
            assert len(filenames) > 0, 'No filenames!'
            # save all the roots, in order, to be processed later
            self.roots = [et.parse(f).getroot() for f in filenames]

    def combine(self):
        for r in self.roots[1:]:
            # combine each element with the first one, and update that
            self.combine_element(self.roots[0], r)
        # return the string representation
        return et.ElementTree(self.roots[0])

    def combine_element(self, one, other):
        """
        This function recursively updates either the text or the children
        of an element if another element is found in `one`, or adds it
        from `other` if not found.
        """
        # Create a mapping from tag name to element, as that's what we are fltering with
        mapping = {(el.tag, hashabledict(el.attrib)): el for el in one}
        for el in other:
            if len(el) == 0:
                # Not nested
                try:
                    # Update the text
                    mapping[(el.tag, hashabledict(el.attrib))].text = el.text
                except KeyError:
                    # An element with this name is not in the mapping
                    mapping[(el.tag, hashabledict(el.attrib))] = el
                    # Add it
                    one.append(el)
            else:
                try:
                    # Recursively process the element, and update it in the same way
                    self.combine_element(mapping[(el.tag, hashabledict(el.attrib))], el)
                except KeyError:
                    # Not in the mapping
                    mapping[(el.tag, hashabledict(el.attrib))] = el
                    # Just add it
                    one.append(el)

if __name__ == '__main__':

    r = XMLCombiner(sys.argv[1:-1]).combine()
    print '-'*20
    print et.tostring(r.getroot())
    r.write(sys.argv[-1], encoding="iso-8859-1", xml_declaration=True)