避免在 python 中将 < 字符写入 XML

Question

我正在尝试将此文本值写入 XML 标记，如下所示

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

每当我将此值设置为该标签的文本时。它像这样生成

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

我需要尝试避免代码中出现转义字符

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

我怎样才能避免像这样写入 xml 文件？我需要避免在 XML 中转义字符。

这是我的完整代码：

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("<![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")

---

这与如何使用 ElementTree 输出 CDATA不同，在某种程度上，我在元素创建时遇到此问题，但在创建 xml 后不进行美化/删除。

Answer 1

如果是我，我会使用lxml 的CDATAclass。

但是，如果您想坚持使用 ElementTree，您可能可以重新定义ET._escape_cdata并确保文本在转义之前不以 开头<![CDATA[，也不以 结尾]]>。

例子...

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 输出（test.xml；打印精美以提高可读性）

<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>

更新：Python 2.7 的函数

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)