使用Python/ElementTree在XML中插入元素的节点

Question

当值小于5时,我需要遍历XML树以添加子元素.例如,可以将此XML修改为

<?xml version="1.0" encoding="UTF-8"?>
<A value="45">
    <B value="30">
        <C value="10"/>
        <C value ="20"/>
    </B>
    <B value="15">
        <C value = "5" />
        <C value = "10" />
    </B>
</A>

这个XML.

<?xml version="1.0" encoding="UTF-8"?>
<A value="45">
    <B value="30">
        <C value="10"/>               
        <C value ="20"/>
    </B>
    <B value="15">
        <C value = "5"><D name="error"/></C>
        <C value = "10" />
    </B>
</A>

我怎么能用Python的ElementTree做到这一点？

Answer 1

你可能犯了一个拼写错误,因为在这个例子中,一个错误元素被追加为一个元素的子元素,它的值是10,不小于5.但我认为这是个主意:

#!/usr/bin/env python

from xml.etree.ElementTree import fromstring, ElementTree, Element

def validate_node(elem):
    for child in elem.getchildren():
        validate_node(child)
        value = child.attrib.get('value', '')
        if not value.isdigit() or int(value) < 5:
            child.append(Element('D', {'name': 'error'}))

if __name__ == '__main__':
    import sys
    xml = sys.stdin.read() # read XML from standard input
    root = fromstring(xml) # parse into XML element tree
    validate_node(root)
    ElementTree(root).write(sys.stdout, encoding='utf-8')
            # write resulting XML to standard output

鉴于此输入:

<?xml version="1.0" encoding="UTF-8"?>
<A value="45">
    <B value="30">
        <C value="1"/>
        <C value="20"/>
    </B>
    <B value="15">
        <C value="5" />
        <C value="10" />
        <C value="foo" />
    </B>
</A>

这是输出:

<A value="45">
    <B value="30">
        <C value="1"><D name="error" /></C>
        <C value="20" />
    </B>
    <B value="15">
        <C value="5" />
        <C value="10" />
        <C value="foo"><D name="error" /></C>
    </B>
</A>