我如何使用断言（启动XSD）

Question

我想更新 homeAppliances.xsd，以便该元素具有依赖于 kind 属性值（以该值为条件）的内容（类型）。

我还想添加更多具有不同类型家用电器的电器。

请注意，每个元素都有一个 kind 属性，该属性指定该电器是立体声电器还是榨汁机电器。

我的目标是输出应该只显示那些具有“kind”属性的设备

这是我的 xml

<?xml version="1.0"?>
<homeAppliances>

  <appliance kind="stereo">
      <description>My stereo</description>
      <brand>Sony</brand>
      <type>Hi-fi</type>
  </appliance>

  <appliance kind="juicer">
      <description>Theres just no substitute for a properly squeezed orange in the morning. 
         So delicate and refreshing. The finest hotels use mechanical juicers of this type for their 
         most discriminating guests. This is the largest selling juicer of its kind. Its a beautiful 
         little all-metal piece in baked enamel and polished chrome; it even won the Frankfurt Fair Award 
         for its design. Uses no electricity and produces no non-recyclable waste as do frozen juices.</description>
      <warranty>lifetime warranty</warranty>
      <name>OJ Home Juicer</name>
      <image>images\mighty_oj.gif</image>
      <cost>41.95</cost>
      <retailer>http://www.thewhitewhale.com/oj.htm</retailer>
  </appliance>

这是我的 xsd

<?xml version="1.0"?>



<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
       elementFormDefault="qualified">


<xs:complexType name="appliance">
    <xs:sequence>
        <xs:element name="description" type="xs:string" />
        <xs:element name="warranty" type="xs:string" minOccurs="0" />
    </xs:sequence>
    <xs:attribute name="kind" type="xs:string" use="required" />
</xs:complexType>


<xs:complexType name="stereoAppliance">
    <xs:complexContent>
        <xs:extension base="appliance">
            <xs:sequence>
                <xs:element name="brand" type="xs:string"/>
                <xs:element name="type" type="xs:string"/>
            </xs:sequence>
        </xs:extension>
    </xs:complexContent>
</xs:complexType>


<xs:complexType name="juiceAppliance">
    <xs:complexContent>
        <xs:extension base="appliance">
            <xs:sequence>
                <xs:element name="name" type="xs:string" />
                <xs:element name="image" type="xs:string" />
                <xs:element name="weight" type="xs:unsignedByte" minOccurs="0" />
                <xs:element name="cost" type="xs:decimal" />
                <xs:element name="retailer" type="xs:anyURI" />
            </xs:sequence>
        </xs:extension>
    </xs:complexContent>
</xs:complexType>


<xs:element name="homeAppliances">
    <xs:complexType>
        <xs:sequence>
            <xs:element name="appliance" type="appliance" maxOccurs="unbounded"/>
        </xs:sequence>
    </xs:complexType>
</xs:element>

</xs:schema>

Answer 1

这是不可能的。 XSD不支持条件约束。我建议的是摆脱类型属性并将其值用作元素的名称。

<?xml version="1.0"?>
<homeAppliances>
    
    <stereo>
        <description>My stereo</description>
        <brand>Sony</brand>
        <type>Hi-fi</type>
    </stereo>
    
    <juicer>
        <description>Theres just no substitute for a properly squeezed orange in the morning. 
            So delicate and refreshing. The finest hotels use mechanical juicers of this type for their 
            most discriminating guests. This is the largest selling juicer of its kind. Its a beautiful 
            little all-metal piece in baked enamel and polished chrome; it even won the Frankfurt Fair Award 
            for its design. Uses no electricity and produces no non-recyclable waste as do frozen juices.</description>
        <warranty>lifetime warranty</warranty>
        <name>OJ Home Juicer</name>
        <image>images\mighty_oj.gif</image>
        <cost>41.95</cost>
        <retailer>http://www.thewhitewhale.com/oj.htm</retailer>
    </juicer>
</homeAppliances>

在XSD中，您可以通过XS：选择：

<xs:element name="homeAppliances">
        <xs:complexType>
            <xs:sequence>
                <xs:choice maxOccurs="unbounded">
                    <xs:element name="stereo" type="stereoAppliance"/>
                    <xs:element name="juice" type="juiceAppliance"/>
                </xs:choice>                
            </xs:sequence>
        </xs:complexType>
    </xs:element>