是否可以定义XSD复杂类型以基于枚举属性的值来验证属性使用？

Question

The following XSD defines a complex type which can either have class="BIT" and a size, OR class="CHAR" and an encoding. The elements this type will be used for will not have any content.

<xs:complexType>
    <xs:attribute name="class">
        <xs:simpleType>
            <xs:restriction base="xs:string">
                <xs:enumeration value="CHAR"/>
                <xs:enumeration value="BIT"/>
            </xs:restriction>
        </xs:simpleType>
    </xs:attribute>
    <xs:attribute name="size" type="xs:integer" />
    <xs:attribute name="encoding" type="xs:string" />
</xs:complexType>

Is there a way I can change this complex type definition so size is required if the class is BIT or encoding is required if the class is CHAR?

The existence of the size or encoding attributes should be mutually exclusive, having an encoding for BIT or having a size for CHAR would be meaningless in the context it is being used.

Answer 1

If it is permissible to alter the schema the following should work but an explicit xsi:type attribute will be needed for elements of the base type in the XML instances of this schema. The way it works is a base type has been created with the class attribute, extended to include the size and encoding attributes, and then restricted. Elements can be declared in the schema as the base type and instances can use the restricted types.

<!-- Base Read Mode Simple Type -->

<xs:simpleType name="MyReadModeType">
    <xs:restriction base="xs:string">
        <xs:enumeration value="CHAR"/>
        <xs:enumeration value="BIT"/>
    </xs:restriction>
</xs:simpleType>

<!-- Char Read Mode Simple Type -->

<xs:simpleType name="MyCharReadModeType">
    <xs:restriction base="tns:MyReadModeType">
        <xs:enumeration value="CHAR"/>
    </xs:restriction>
</xs:simpleType>

<!-- Bit Read Mode Simple Type -->

<xs:simpleType name="MyBitReadModeType">
    <xs:restriction base="tns:MyReadModeType">
        <xs:enumeration value="BIT"/>
    </xs:restriction>
</xs:simpleType>

<!-- Set Read Mode Base Type -->

<xs:complexType name="MySetReadModeType" abstract="true">
    <xs:attribute name="class" type="tns:MyReadModeType" />
</xs:complexType>

<!-- Set Char Mode Extension -->

<xs:complexType name="MyBaseSetCharReadModeType" abstract="true">
    <xs:complexContent>
        <xs:extension base="tns:MySetReadModeType">
            <xs:attribute name="size" type="tns:MyReadModeSizeType" use="prohibited" />
            <xs:attribute name="encoding" type="xs:string" use="required"/>
        </xs:extension>
    </xs:complexContent>
</xs:complexType>

<!-- Set Char Mode Type -->

<xs:complexType name="charMode">
    <xs:complexContent>
        <xs:restriction base="tns:MyBaseSetCharReadModeType">
            <xs:attribute name="size" type="tns:MyReadModeSizeType" use="prohibited" />
            <xs:attribute name="encoding" type="xs:string" use="required"/>
            <xs:attribute name="class" type="tns:MyCharReadModeType" use="optional" default="CHAR" />
        </xs:restriction>
    </xs:complexContent>
</xs:complexType>

<!-- Set Bit Mode Extension -->

<xs:complexType name="MyBaseSetBitReadModeType" abstract="true">
    <xs:complexContent>
        <xs:extension base="tns:MySetReadModeType">
            <xs:attribute name="size" type="tns:MyReadModeSizeType" use="required" />
            <xs:attribute name="encoding" type="xs:string" use="prohibited"/>
        </xs:extension>
    </xs:complexContent>
</xs:complexType>

<!-- Set Bit Mode Type -->

<xs:complexType name="bitMode">
    <xs:complexContent>
        <xs:restriction base="tns:MyBaseSetBitReadModeType">
            <xs:attribute name="size" type="tns:MyReadModeSizeType" use="required" />
            <xs:attribute name="encoding" type="xs:string" use="prohibited"/>
            <xs:attribute name="class" type="tns:MyBitReadModeType" use="optional" default="BIT"/>
        </xs:restriction>
    </xs:complexContent>
</xs:complexType>