lxml包含相对路径

时间:2019-04-10 14:42:18

标签: python xml xsd lxml

我正在使用Python的lxml库来加载.xsd作为架构。 Python脚本位于一个目录中,而模式位于另一个目录中:

/root
    my_script.py
    /data
        /xsd
            schema_1.xsd
            schema_2.xsd

问题是schema_1.xsd包含schema_2.xsd,如下所示:

<xsd:include schemaLocation="schema_2.xsd"/>

由于schema_2.xsd是相对路径(两个模式位于同一目录中),因此lxml找不到它,并且它会上升并出现错误:

schema_root = etree.fromstring(open('data/xsd/schema_1.xsd').read().encode('utf-8'))
schema = etree.XMLSchema(schema_root)

--> xml.etree.XMLSchemaParseError: Element '{http://www.w3.org/2001/XMLSchema}include': Failed to load the document './schema_2.xsd' for inclusion

如何在不更改架构文件的情况下解决此问题?

1 个答案:

答案 0 :(得分:1)

一种选择是使用XML Catalog。您可能还可以使用自定义URI Resolver,但是我一直使用目录。非开发人员更容易进行配置更改。如果您要提供的是可执行文件而不是普通的Python,这将特别有用。

在Windows和Linux之间,使用目录是不同的。 see here for more info

这是一个使用Python 3.#的Windows示例。

XSD#1 (schema_1.xsd)

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
  <xs:include schemaLocation="schema_2.xsd"/>

  <xs:element name="doc">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="test"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="test" type="test"/>
</xs:schema>

XSD#2 (schema_2.xsd)

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
    <xs:simpleType name="test">
        <xs:restriction base="xs:string">
            <xs:enumeration value="Hello World"/>
        </xs:restriction>
    </xs:simpleType>
</xs:schema>

XML目录(catalog.xml)

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE catalog PUBLIC "-//OASIS//DTD XML Catalogs V1.1//EN" "http://www.oasis-open.org/committees/entity/release/1.1/catalog.dtd">
<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog">
    <!-- The path in @uri is relative to this file (catalog.xml). -->
    <system systemId="schema_2.xsd" uri="./xsd_test/schema_2.xsd"/>
</catalog>

Python

import os
from urllib.request import pathname2url
from lxml import etree

# The XML_CATALOG_FILES environment variable is used by libxml2 (which is used by lxml).
# See http://xmlsoft.org/catalog.html.
if "XML_CATALOG_FILES" not in os.environ:
    # Path to catalog must be a url.
    catalog_path = f"file:{pathname2url(os.path.join(os.getcwd(), 'catalog.xml'))}"
    # Temporarily set the environment variable.
    os.environ['XML_CATALOG_FILES'] = catalog_path

schema_root = etree.fromstring(open('xsd_test/schema_1.xsd').read().encode('utf-8'))
schema = etree.XMLSchema(schema_root)

print(schema)

打印输出

<lxml.etree.XMLSchema object at 0x02B4B3F0>