使xs和xmls：xsi属性成为XSD中必需的属性

Question

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xs:element name="translator">
        ...
    </xs:element>
</xs:schema>

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="Translator.xsd"

如果我把它们放在XSD中，像这样

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xs:element name="translator">
         <xs:attribute name="xmlns:xsi" type="xs:string" default="http://www.w3.org/2001/XMLSchema-instance"/>
         <xs:attribute name="xsi:noNamespaceSchemaLocation" type="xs:string" default="Translator.xsd"/>
    </xs:element>
</xs:schema>

Xerces报告了以下问题

[Error] :678:114: s4s-att-invalid-value: Invalid attribute value for 'name' in element 'attribute'. Recorded reason: cvc-datatype-valid.1.2.1: 'xmlns:xsi' is not a valid value for 'NCName'.
[Error] :678:114: src-attribute.3.1: One of 'ref' or 'name' must be present in a local attribute declaration.
[Error] :679:117: s4s-att-invalid-value: Invalid attribute value for 'name' in element 'attribute'. Recorded reason: cvc-datatype-valid.1.2.1: 'xsi:noNamespaceSchemaLocation' is not a valid value for 'NCName'.
[Error] :679:117: src-attribute.3.1: One of 'ref' or 'name' must be present in a local attribute declaration.

Answer 1

首先警告：XML Schema规范禁止在XML Schema实例命名空间中声明属性，并显式阻止更改其行为的尝试。

话虽如此，您所得到的错误的原因是name属性只支持通过提供新元素的本地名称来定义目标命名空间中的新元素（在本例中不支持命名空间中的新元素）。

从技术上讲，您可以通过引用xsi：nonamespaceSchemaLocation属性来执行类似的操作，该属性已经在builtin XML架构实例命名空间中定义：

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <xs:element name="translator">
        <xs:complexType>
            <xs:simpleContent>
                <xs:extension base="xs:string">
                    <xs:attribute ref="xsi:noNamespaceSchemaLocation" default="Translator.xsd"/>
                </xs:extension>
            </xs:simpleContent>
        </xs:complexType>
    </xs:element>
</xs:schema>