Python minidom:如何访问元素 [英] Python minidom: How to access an element

问题描述

我正在用 Python 解析 XML-Sheet.XML 具有如下结构:

I'm working on parsing an XML-Sheet in Python. The XML has a structure like this:

<layer1>
    <layer2>
        <element>
            <info1></info1>
        </element>
        <element>
            <info1></info1>
        </element>
        <element>
            <info1></info1>
        </element>
    </layer2>
</layer1>

如果没有 layer2，我访问 info1 中的数据没有问题.但是对于layer2，我真的遇到了麻烦.他们的我可以通过以下方式处理 info1:root.firstChild.childNodes[0].childNodes[0].data

Without layer2, I have no problems to acess the data in info1. But with layer2, I'm really in trouble. Their I can adress info1 with: root.firstChild.childNodes[0].childNodes[0].data

所以我的想法是，我可以这样做:root.firstChild.firstChild.childNodes[0].childNodes[0].data

So my thought was, that I can do it similiar like this:root.firstChild.firstChild.childNodes[0].childNodes[0].data

这就是我解决问题的方法:从 xml.etree 导入 cElementTree 作为 ET

So this is how I solved my problem: from xml.etree import cElementTree as ET

从 xml.etree 导入 cElementTree 作为 ET

from xml.etree import cElementTree as ET

tree = ET.parse("test.xml")
root = tree.getroot()

for elem in root.findall('./layer2/'):
    for node in elem.findall('element/'):
        x = node.find('info1').text
        if x != "abc":
            elem.remove(node)

推荐答案

如果您能提供帮助，请不要使用 minidom API.改用 ElementTree API；xml.dom.minidom 文档明确指出:

Don't use the minidom API if you can help it. Use the ElementTree API instead; the xml.dom.minidom documentation explicitly states that:

尚未精通 DOM 的用户应考虑改用 xml.etree.ElementTree 模块进行 XML 处理.

Users who are not already proficient with the DOM should consider using the xml.etree.ElementTree module for their XML processing instead.

以下是使用 ElementTree API 访问元素的简短示例:

Here is a short sample that uses the ElementTree API to access your elements:

from xml.etree import ElementTree as ET

tree = ET.parse('inputfile.xml')

for info in tree.findall('.//element/info1'):
    print info.text

这使用 XPath 表达式列出包含在 element 元素中的所有 info1 元素，而不管它们在整个 XML 文档中的位置.

This uses an XPath expression to list all info1 elements that are contained inside a element element, regardless of their position in the overall XML document.

如果您只需要first info1 元素，请使用.find():

If all you need is the first info1 element, use .find():

print tree.find('.//info1').text

使用 DOM API，.firstChild 可以轻松成为 Text 节点而不是 Element 节点；你总是需要遍历 .childNotes 序列来找到第一个 Element 匹配:

With the DOM API, .firstChild could easily be a Text node instead of an Element node; you always need to loop over the .childNotes sequence to find the first Element match:

def findFirstElement(node):
    for child in node.childNodes:
        if child.nodeType == node.ELEMENT_NODE:
            return child

但对于您的情况，也许使用 .getElementsByTagName() 就够了:

but for your case, perhaps using .getElementsByTagName() suffices:

root.getElementsByTagName('info1').data

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