在Python中使用ElementTree发出名称空间规范

Question

我试图发出带有元素树的XML文件，其中包含XML声明和名称空间。这是我的示例代码：

from xml.etree import ElementTree as ET
ET.register_namespace('com',"http://www.company.com") #some name

# build a tree structure
root = ET.Element("STUFF")
body = ET.SubElement(root, "MORE_STUFF")
body.text = "STUFF EVERYWHERE!"

# wrap it in an ElementTree instance, and save as XML
tree = ET.ElementTree(root)

tree.write("page.xml",
           xml_declaration=True,
           method="xml" )

但是，既不会出现<?xml标签，也不会出现任何名称空间/前缀信息。我在这里有点困惑。

Answer 1

尽管文档另有说明，但我只能<?xml>通过同时指定xml_declaration和编码来获得声明。

您必须在已注册的名称空间中声明节点，以在文件中的节点上获取名称空间。这是您的代码的固定版本：

from xml.etree import ElementTree as ET
ET.register_namespace('com',"http://www.company.com") #some name

# build a tree structure
root = ET.Element("{http://www.company.com}STUFF")
body = ET.SubElement(root, "{http://www.company.com}MORE_STUFF")
body.text = "STUFF EVERYWHERE!"

# wrap it in an ElementTree instance, and save as XML
tree = ET.ElementTree(root)

tree.write("page.xml",
           xml_declaration=True,encoding='utf-8',
           method="xml")

输出（page.xml）

<?xml version='1.0' encoding='utf-8'?><com:STUFF xmlns:com="http://www.company.com"><com:MORE_STUFF>STUFF EVERYWHERE!</com:MORE_STUFF></com:STUFF>

ElementTree也不漂亮。这是打印精美的输出：

<?xml version='1.0' encoding='utf-8'?>
<com:STUFF xmlns:com="http://www.company.com">
    <com:MORE_STUFF>STUFF EVERYWHERE!</com:MORE_STUFF>
</com:STUFF>

您还可以声明一个默认名称空间，而无需注册一个名称空间：

from xml.etree import ElementTree as ET

# build a tree structure
root = ET.Element("{http://www.company.com}STUFF")
body = ET.SubElement(root, "{http://www.company.com}MORE_STUFF")
body.text = "STUFF EVERYWHERE!"

# wrap it in an ElementTree instance, and save as XML
tree = ET.ElementTree(root)

tree.write("page.xml",
           xml_declaration=True,encoding='utf-8',
           method="xml",default_namespace='http://www.company.com')

输出（漂亮的打印间隔是我的）

<?xml version='1.0' encoding='utf-8'?>
<STUFF xmlns="http://www.company.com">
    <MORE_STUFF>STUFF EVERYWHERE!</MORE_STUFF>
</STUFF>