Avoid writing < character to XML in python

问题

I am trying to write this text value to the XML tag like this

 <Parameter name="name"><![CDATA[xyzvalue]]></Parameter>

Whenever, i am setting this value as text to this tag. It generates it like this

<Parameter name="name">&lt;![CDATA[xyzvalue]]&gt;</Parameter>

I need have tried to avoid unescape characters in the code

ET.SubElement(parameters, "Parameter", name="id").text = unescape("&lt;![CDATA[xyzvalue]]>")

How can i avoid it writing like this to the xml file ? I need to avoid escaping characters in the XML.

This is my complete code:

map = ET.Element("Map")

parameters = ET.SubElement(map, "Parameters")
ET.SubElement(parameters, "Parameter", name="bounds").text = "-180,-85.05112877980659,180,85.05112877980659"
ET.SubElement(parameters, "Parameter", name="center").text = "0,0,2"
ET.SubElement(parameters, "Parameter", name="format").text = "png"
ET.SubElement(parameters, "Parameter", name="minzoom").text = "0"
ET.SubElement(parameters, "Parameter", name="maxzoom").text = "22"
ET.SubElement(parameters, "Parameter", name="scale").text = "1"
ET.SubElement(parameters, "Parameter", name="metatile").text = "2"
ET.SubElement(parameters, "Parameter", name="id").text = unescape("&lt;![CDATA[xyzvalue]]>")
ET.SubElement(parameters, "Parameter", name="_updated").text = "1552288036000"
ET.SubElement(parameters, "Parameter", name="name").text = "<![CDATA[xyzvalue]]>"
ET.SubElement(parameters, "Parameter", name="tilejson").text = "<![CDATA[2.0.0]]>"
ET.SubElement(parameters, "Parameter", name="scheme").text = "<![CDATA[xyz]]>"

indent(map)
tree = ET.ElementTree(map)
tree.write("plotfinder_tiles.xml", xml_declaration=True, encoding='utf-8', method="xml")

This is different to How to output CDATA using ElementTree, in a way, that i have this issue at the Element creation not to prettify/ remove after xml has been created.

回答1:

If it were me, I'd use lxml's CDATA class.

However, if you wanted to stick with ElementTree you could probably redefine ET._escape_cdata and make sure the text doesn't start with <![CDATA[ and doesn't end with ]]> before escaping.

Example...

Python 3.#

import xml.etree.ElementTree as ET


def escape_cdata(text):
    # escape character data
    try:
        if not text.startswith("<![CDATA[") and not text.endswith("]]>"):
            if "&" in text:
                text = text.replace("&", "&amp;")
            if "<" in text:
                text = text.replace("<", "&lt;")
            if ">" in text:
                text = text.replace(">", "&gt;")
        return text
    except (TypeError, AttributeError):
        ET._raise_serialization_error(text)


ET._escape_cdata = escape_cdata

map_elem = ET.Element("Map")

parameters = ET.SubElement(map_elem, "Parameters")
ET.SubElement(parameters, "Parameter", name="bounds").text = "-180,-85.05112877980659,180,85.05112877980659"
ET.SubElement(parameters, "Parameter", name="center").text = "0,0,2"
ET.SubElement(parameters, "Parameter", name="format").text = "png"
ET.SubElement(parameters, "Parameter", name="minzoom").text = "0"
ET.SubElement(parameters, "Parameter", name="maxzoom").text = "22"
ET.SubElement(parameters, "Parameter", name="scale").text = "1"
ET.SubElement(parameters, "Parameter", name="metatile").text = "2"
ET.SubElement(parameters, "Parameter", name="id").text = "<![CDATA[xyzvalue]]>"
ET.SubElement(parameters, "Parameter", name="_updated").text = "1552288036000"
ET.SubElement(parameters, "Parameter", name="name").text = "<![CDATA[xyzvalue]]>"
ET.SubElement(parameters, "Parameter", name="tilejson").text = "<![CDATA[2.0.0]]>"
ET.SubElement(parameters, "Parameter", name="scheme").text = "<![CDATA[xyz]]>"

tree = ET.ElementTree(map_elem)
tree.write("test.xml", xml_declaration=True, encoding='utf-8', method="xml")

XML Output (test.xml; pretty printed for readability)

<Map>
    <Parameters>
        <Parameter name="bounds">-180,-85.05112877980659,180,85.05112877980659</Parameter>
        <Parameter name="center">0,0,2</Parameter>
        <Parameter name="format">png</Parameter>
        <Parameter name="minzoom">0</Parameter>
        <Parameter name="maxzoom">22</Parameter>
        <Parameter name="scale">1</Parameter>
        <Parameter name="metatile">2</Parameter>
        <Parameter name="id"><![CDATA[xyzvalue]]></Parameter>
        <Parameter name="_updated">1552288036000</Parameter>
        <Parameter name="name"><![CDATA[xyzvalue]]></Parameter>
        <Parameter name="tilejson"><![CDATA[2.0.0]]></Parameter>
        <Parameter name="scheme"><![CDATA[xyz]]></Parameter>
    </Parameters>
</Map>

Update: Function for Python 2.7

def escape_cdata(text, encoding):
    # escape character data
    try:
        if not text.startswith("<![CDATA[") and not text.endswith("]]>"):
            if "&" in text:
                text = text.replace("&", "&amp;")
            if "<" in text:
                text = text.replace("<", "&lt;")
            if ">" in text:
                text = text.replace(">", "&gt;")
        return text.encode(encoding, "xmlcharrefreplace")
    except (TypeError, AttributeError):
        ET._raise_serialization_error(text)

来源：https://stackoverflow.com/questions/55141512/avoid-writing-character-to-xml-in-python

标签

python

xml

python-2.7

elementtree