python - ElementTree:为什么我的 namespace 声明被删除了？

Question

我正在构建 openoffice 文档。我有一个用于生成 content.xml 文件的脚手架。 content-scaffold.xml 文件存储在文件系统中，如下所示:

<?xml version="1.0" encoding="UTF-8"?>
  <office:document-content
  xmlns:anim="urn:oasis:names:tc:opendocument:xmlns:animation:1.0"
  xmlns:chart="urn:oasis:names:tc:opendocument:xmlns:chart:1.0"
  xmlns:config="urn:oasis:names:tc:opendocument:xmlns:config:1.0"
  xmlns:db="urn:oasis:names:tc:opendocument:xmlns:database:1.0"
  xmlns:dc="http://purl.org/dc/elements/1.1/"
  xmlns:dr3d="urn:oasis:names:tc:opendocument:xmlns:dr3d:1.0"
  xmlns:draw="urn:oasis:names:tc:opendocument:xmlns:drawing:1.0"
  xmlns:fo="urn:oasis:names:tc:opendocument:xmlns:xsl-fo-compatible:1.0"
  xmlns:form="urn:oasis:names:tc:opendocument:xmlns:form:1.0"
  xmlns:grddl="http://www.w3.org/2003/g/data-view#"
  xmlns:manifest="urn:oasis:names:tc:opendocument:xmlns:manifest:1.0"
  xmlns:math="http://www.w3.org/1998/Math/MathML"
  xmlns:meta="urn:oasis:names:tc:opendocument:xmlns:meta:1.0"
  xmlns:number="urn:oasis:names:tc:opendocument:xmlns:datastyle:1.0"
  xmlns:odf="http://docs.oasis-open.org/ns/office/1.2/meta/odf#"
  xmlns:of="urn:oasis:names:tc:opendocument:xmlns:of:1.2"
  xmlns:office="urn:oasis:names:tc:opendocument:xmlns:office:1.0"
  xmlns:pkg="http://docs.oasis-open.org/ns/office/1.2/meta/pkg#"
  xmlns:presentation="urn:oasis:names:tc:opendocument:xmlns:presentation:1.0"
  xmlns:script="urn:oasis:names:tc:opendocument:xmlns:script:1.0"
  xmlns:smil="urn:oasis:names:tc:opendocument:xmlns:smil-compatible:1.0"
  xmlns:style="urn:oasis:names:tc:opendocument:xmlns:style:1.0"
  xmlns:svg="urn:oasis:names:tc:opendocument:xmlns:svg-compatible:1.0"
  xmlns:table="urn:oasis:names:tc:opendocument:xmlns:table:1.0"
  xmlns:text="urn:oasis:names:tc:opendocument:xmlns:text:1.0"
  xmlns:xforms="http://www.w3.org/2002/xforms"
  xmlns:xhtml="http://www.w3.org/1999/xhtml"
  xmlns:xlink="http://www.w3.org/1999/xlink"
  office:version="1.2">

  <office:automatic-styles>

    <style:style style:family="text" style:name="Strong">
      <style:text-properties
        fo:color="#000000"
        fo:font-weight="bold" />
    </style:style>

  </office:automatic-styles>


  <office:body>
    <office:text>
      <!-- content will go here -->
    </office:text>
  </office:body>

</office:document-content>

我的想法是，我采用此 xml 并将内容注入(inject) office:text 标记(在 python 中)，然后将其渲染回来。在这个例子中，我注入(inject)了一个简单的 text:p 标签。

document_content = ElementTree.parse('content-scaffold.xml').getroot()
office_body = document_content.find('office:body', NAMESPACES)
office_text = office_body.find('office:text', NAMESPACES)
p = ElementTree.SubElement(office_text, 'text:p')
p.text = "Hello"

然而，这是命名空间声明在呈现后的样子:

<office:document-content 
xmlns:fo="urn:oasis:names:tc:opendocument:xmlns:xsl-fo-compatible:1.0"
xmlns:office="urn:oasis:names:tc:opendocument:xmlns:office:1.0" 
xmlns:style="urn:oasis:names:tc:opendocument:xmlns:style:1.0"
office:version="1.2">

这会导致以下错误:

Namespace prefix text on p is not defined

很明显，ElementTree 只保留需要的 xmlns 声明(在我的例子中是 fo、office 和 style，因为它们是 content-scaffold.xml 中唯一存在的声明)，而且非常简洁。但是，我真的想要它们，以便能够使用所有 namespace 。

知道如何强制 ElementTree 保留它们吗？还是我从一开始就认为这是错误的？我愿意接受任何替代解决方案。

注意:我使用的是 Python 3 和 ElementTree

谢谢

Answer 1

ElementTree 在命名空间处理方面相当薄弱。但是，你要求的是可以做到的(但是有点麻烦):

from xml.etree import ElementTree as ET

NAMESPACES = {"anim": "urn:oasis:names:tc:opendocument:xmlns:animation:1.0",
  "chart": "urn:oasis:names:tc:opendocument:xmlns:chart:1.0",
  "config": "urn:oasis:names:tc:opendocument:xmlns:config:1.0",
  "db": "urn:oasis:names:tc:opendocument:xmlns:database:1.0",
  "dc": "http://purl.org/dc/elements/1.1/",
  "dr3d": "urn:oasis:names:tc:opendocument:xmlns:dr3d:1.0",
  "draw": "urn:oasis:names:tc:opendocument:xmlns:drawing:1.0",
  "fo": "urn:oasis:names:tc:opendocument:xmlns:xsl-fo-compatible:1.0",
  "form": "urn:oasis:names:tc:opendocument:xmlns:form:1.0",
  "grddl": "http://www.w3.org/2003/g/data-view#",
  "manifest": "urn:oasis:names:tc:opendocument:xmlns:manifest:1.0",
  "math": "http://www.w3.org/1998/Math/MathML",
  "meta": "urn:oasis:names:tc:opendocument:xmlns:meta:1.0",
  "number": "urn:oasis:names:tc:opendocument:xmlns:datastyle:1.0",
  "odf": "http://docs.oasis-open.org/ns/office/1.2/meta/odf#",
  "of": "urn:oasis:names:tc:opendocument:xmlns:of:1.2",
  "office": "urn:oasis:names:tc:opendocument:xmlns:office:1.0",
  "pkg": "http://docs.oasis-open.org/ns/office/1.2/meta/pkg#",
  "presentation": "urn:oasis:names:tc:opendocument:xmlns:presentation:1.0",
  "script": "urn:oasis:names:tc:opendocument:xmlns:script:1.0",
  "smil": "urn:oasis:names:tc:opendocument:xmlns:smil-compatible:1.0",
  "style": "urn:oasis:names:tc:opendocument:xmlns:style:1.0",
  "svg": "urn:oasis:names:tc:opendocument:xmlns:svg-compatible:1.0",
  "table": "urn:oasis:names:tc:opendocument:xmlns:table:1.0",
  "text": "urn:oasis:names:tc:opendocument:xmlns:text:1.0",
  "xforms": "http://www.w3.org/2002/xforms",
  "xhtml": "http://www.w3.org/1999/xhtml",
  "xlink": "http://www.w3.org/1999/xlink"}

document_content = ET.parse('content-scaffold.xml').getroot()
office_body = document_content.find('office:body',  NAMESPACES)
office_text = office_body.find('office:text', NAMESPACES)
p = ET.SubElement(office_text, 'text:p')
p.text = "Hello"

for prefix, uri in NAMESPACES.items():
    ET.register_namespace(prefix, uri)           # Ensure correct prefixes in output 
    if prefix not in ("office", "fo", "style"):  # Prevent duplicate ns declarations
        document_content.set("xmlns:" + prefix, uri)   # Add ns declarations to root element

ET.ElementTree(document_content).write("output.xml")

此代码将创建一个保留所有命名空间声明的结果文档。

---

这是如何使用 lxml 完成的:

from lxml import etree as ET

NAMESPACES = {"office": "urn:oasis:names:tc:opendocument:xmlns:office:1.0"}

document_content = ET.parse('content-scaffold.xml')
office_body = document_content.find('office:body', NAMESPACES)
office_text = office_body.find('office:text', NAMESPACES)
p = ET.SubElement(office_text, '{urn:oasis:names:tc:opendocument:xmlns:text:1.0}p')
p.text = "Hello"

document_content.write("output.xml")

请注意，您必须使用 Clark notation 提供元素名称在 SubElement() 中。