如何在xsd中引用属性

我尝试定义一个可以在后续元素定义中引用的属性。

<xs:attribute name="ridref" type="xs:string"/>

后来我这样使用它：

<xs:element name="coordRegRef">
  <xs:complexType>
    <!--xs:attribute name="ridref" type="xs:string"/ this works but I want to use ref -->
    <xs:attribute ref="ridref" use="required"/>
  </xs:complexType>
</xs:element>

XSD 使用 xmllint 可以正常编译

xmllint --schema pc-ar.xsd pc-ar.xml

但 xmllint 说

pc-ar.xml:41: element coordRegRef: Schemas validity error : Element '{http://pc-ar.xsd}coordRegRef', attribute 'ridref': The attribute 'ridref' is not allowed.
pc-ar.xml:41: element coordRegRef: Schemas validity error : Element '{http://pc-ar.xsd}coordRegRef': The attribute '{http://pc-ar.xsd}ridref' is required but missing.

我将其解释为我的 XML 文件必须使用ridref 的命名空间

<coordRegRef fix:ridref="111"/>

（这确实有效，但不受欢迎）而不是

<coordRegRef ridref="111"/>

Why?

My XSD

<?xml version="1.0"?>
<!-- validate: xmllint - -schema pc-ar.xsd pc-ar.xml -->
<xs:schema 
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    targetNamespace="http://pc-ar.xsd"
    elementFormDefault="qualified"
    xmlns="http://pc-ar.xsd"
    xmlns:fix="http://pc-ar.xsd">

    <!--xs:attribute name="rid" type="xs:integer"/-->

    <!--xs:attributeGroup name="ridGroup">
    <xs:attribute name="rid" type="xs:integer"> 
        <xs:annotation>
            <xs:documentation>entry id</xs:documentation>
        </xs:annotation>
    </xs:attribute>
</xs:attributeGroup-->

    <xs:element name="name" type="xs:string"/>
    <xs:attribute name="id" type="xs:ID"/>
    <xs:attribute name="idref" type="xs:IDREF"/>

    <xs:attribute name="ridref" type="xs:string"/>

    <xs:element name="coordRegRef">
        <xs:complexType>
            <!--xs:attribute name="ridref" type="xs:string"/works-->
            <xs:attribute ref="ridref" use="required"/>
        </xs:complexType>
    </xs:element>

    <xs:element name="assetRegRef">
        <xs:complexType>
            <xs:sequence>
                <xs:element name="ridref2" type="xs:string"/>
            </xs:sequence>
            <!--xs:attribute name="ridref" type="xs:string"/works-->
            <xs:attribute name="ridref" type="xs:string"/>
        </xs:complexType>
    </xs:element>

    <xs:element name="lat">
        <xs:simpleType>
            <xs:restriction base="xs:decimal">
                <xs:minInclusive value="-40"/>
                <xs:maxInclusive value="-30"/>
            </xs:restriction>
        </xs:simpleType>
    </xs:element>

    <xs:element name="lon" type="xs:decimal"/>

    <xs:complexType name="coordRegTableType">
        <xs:sequence>
            <xs:element name="entry" minOccurs="0" maxOccurs="unbounded">
                <xs:complexType>
                    <xs:sequence>
                        <xs:element ref="name"/>
                        <xs:element ref="lat"/>
                        <xs:element ref="lon"/>
                    </xs:sequence>
                    <xs:attribute name="rid" type="xs:string"/>
                    <!--xs:attribute ref="fix:id" use="required"/-->
                    <xs:attribute name="id" type="xs:string" use="required"/>
                </xs:complexType>
            </xs:element>
        </xs:sequence>
    </xs:complexType>

    <xs:complexType name="assetRegTableType">
        <xs:sequence>
            <xs:element name="entry" minOccurs="0" maxOccurs="unbounded">
                <xs:complexType>
                    <xs:sequence>
                        <xs:element ref="name"/>
                        <xs:element ref="coordRegRef"/>
                        <xs:element ref="assetRegRef"/>
                    </xs:sequence>
                    <xs:attribute name="rid" type="xs:string"/>
                    <xs:attribute name="id" type="xs:string" use="required"/>
                </xs:complexType>
            </xs:element>
        </xs:sequence>
    </xs:complexType>

    <xs:element name="coordReg" type="fix:coordRegTableType">
        <xs:unique name="coordRegNameUniq">
            <xs:selector xpath="*"/>
            <xs:field xpath="fix:name"/>
        </xs:unique>
    </xs:element>

    <xs:element name="assetReg" type="assetRegTableType">
        <xs:unique name="assetRegNameUniq">
            <xs:selector xpath="fix:entry"/>
            <xs:field xpath="fix:name"/>
        </xs:unique>
    </xs:element>

    <xs:element name="assetExchange">
        <xs:complexType>
            <xs:sequence>
                <xs:element ref="coordReg"/>
                <xs:element ref="assetReg"/>
            </xs:sequence>
            <xs:attribute name="rid" type="xs:integer"/>
            <!--xs:attribute ref="id" use="required"/-->
        </xs:complexType>

        <xs:key name="coordRegKey">
            <xs:selector xpath="fix:coordReg/fix:entry"/>
            <xs:field xpath="@rid"/>
        </xs:key>

        <xs:key name="assetRegKey">
            <xs:selector xpath="fix:assetReg/fix:entry"/>
            <xs:field xpath="@rid"/>
        </xs:key>

        <xs:keyref name="assetRegKeyRef" refer="assetRegKey">
            <xs:selector xpath=".//fix:assetRegRef"/>
            <xs:field xpath="@ridref"/>
        </xs:keyref>

        <xs:keyref name="assetRegKeyRef2" refer="assetRegKey">
            <!--xs:selector xpath=".//fix:assetRegRef"/works-->
            <!--xs:selector xpath="./*/*/fix:assetRegRef"/works-->
            <!--xs:selector xpath="./*/fix:entry/fix:assetRegRef"/works-->
            <!--xs:selector xpath="./*/*/fix:assetRegRef"/works-->
            <xs:selector xpath=".//fix:assetRegRef"/> <!-- any assetRefRef -->
            <xs:field xpath="fix:ridref2"/>
        </xs:keyref>

        <xs:keyref name="coordRegKeyRef" refer="coordRegKey">
            <xs:selector xpath=".//fix:coordRegRef"/>
            <xs:field xpath="@ridref"/>
        </xs:keyref>

    </xs:element>

</xs:schema> 

我的 XML 测试文件

<?xml version="1.0"?>

<assetExchange 
  xmlns="http://pc-ar.xsd"
  xmlns:fix="http://pc-ar.xsd"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://pc-ar.xsd pc-ar.xsd"
  rid="1">

<coordReg>
  <entry id="1" rid="111">
    <name>sitea</name>
    <lat>-31.23</lat>
    <lon>151</lon>
  </entry>

  <entry id="2" rid="222">
    <name>siteb</name>
    <lat>-31.23</lat>
    <lon>151</lon>
  </entry>

  <entry id="3" rid="333">
    <name>sitec</name>
    <lat>-31.23</lat>
    <lon>151</lon>
  </entry>
</coordReg>

<assetReg>
  <entry id="11" rid="11">
    <name>deva</name>
    <coordRegRef fix:ridref="111"/>
    <assetRegRef ridref="aa"><ridref2>aa</ridref2></assetRegRef>
  </entry>

  <entry id="22" rid="22">
    <name>devb</name>
    <coordRegRef ridref="2212"/>
    <assetRegRef ridref="11"><ridref2>11</ridref2></assetRegRef>
  </entry>

  <entry id="33" rid="33">
    <name>devc</name>
    <coordRegRef ridref="333"/>
    <assetRegRef ridref="44"><ridref2>44</ridref2></assetRegRef>
  </entry>

</assetReg>

</assetExchange>

正如您所注意到的，并且从验证错误中可以看出，解析器确实期望该属性ridref但它必须在命名空间中。

原因是在 XML 模式中，所有全局元素、属性或类型定义都必须经过限定。这会导致所有全局定义的属性都将以命名空间为前缀，即使您已设置attributeFormDefault="unqualified"。解决方法是在内部单独定义此类属性<xs:attributeGroup>（或在全局类型中）。在这种情况下，属性组的名称将获取附加到它的命名空间，而不是其中属性的名称。然后你可以使用ref引用这些属性组并获取全局可用的属性，而无需将它们放在命名空间中。