如何在XML文件中插入处理指令

Question

我想使用ElementTree(Python 3.8(在XML文件的根元素之前添加一条xml-stylesheet处理指令。

您可以在下面找到我用来创建XML文件的代码

import xml.etree.cElementTree as ET
def Export_star_xml( self ):
star_element = ET.Element("STAR",**{ 'xmlns:xsi': 'http://www.w3.org/2001/XMLSchema-instance' })
element_node = ET.SubElement(star_element ,"STAR_1")
element_node.text = "Mario adam"
tree.write( "star.xml" ,encoding="utf-8", xml_declaration=True )

输出：

<?xml version="1.0" encoding="windows-1252"?>
<STAR xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<STAR_1> Mario adam </STAR_1>
</STAR>    

预期输出：

<?xml version="1.0" encoding="windows-1252"?>
<?xml-stylesheet type="text/xsl" href="ResourceFiles/form_star.xsl"?>
<STAR xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<STAR_1> Mario adam </STAR_1>
</STAR>

Answer 1

我不知道如何使用ElementTree来实现这一点。这里有一个使用lxml的解决方案，它为元素提供了addprevious()方法。

from lxml import etree as ET
# Note the use of nsmap. The syntax used in the question is not accepted by lxml
star_element = ET.Element("STAR", nsmap={'xsi': 'http://www.w3.org/2001/XMLSchema-instance'})
element_node = ET.SubElement(star_element ,"STAR_1")
element_node.text = "Mario adam"
# Create PI and and insert it before the root element
pi = ET.ProcessingInstruction("xml-stylesheet", text='type="text/xsl" href="ResourceFiles/form_star.xsl"')
star_element.addprevious(pi)
ET.ElementTree(star_element).write("star.xml", encoding="utf-8",
xml_declaration=True, pretty_print=True)

结果：

<?xml version='1.0' encoding='UTF-8'?>
<?xml-stylesheet type="text/xsl" href="ResourceFiles/form_star.xsl"?>
<STAR xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<STAR_1>Mario adam</STAR_1>
</STAR>