XSD 限制规则 [英] XSD Restricted Rule

问题描述

有没有办法在 xsd 中创建像外键受限"这样的规则?我需要检查是否存在与节点的属性使用"相等的属性值.

There is a way to create a rule like 'foreign key restricted' in xsd? I need to check the existence of an attribute value that is equal to the attribute 'use' of a node.

<node use="..." />
<otherNode name="..." />

看上面的例子，属性设置为'node'属性'use'，这个属性的值必须等于'name'属性中的'otherNode'

See the example above, the attribute is set to 'node' attribute 'use', the value of this attribute must be equal to 'otherNode' in the 'name' attribute

推荐答案

设置use属性的类型为xs:IDREF

Set the type of the use attribute to xs:IDREF

以及 xs:ID 的 name 属性.

and the name attribute to xs:ID.

还有一个 xs:IDREFS 类型.

There's also an xs:IDREFS type.

一个例子

<xsd:element name="quote">
  <xsd:complexType>
    <!--content model-->
    <xsd:attribute name="ref" type="xsd:IDREF"/>
  </xsd:complexType>
</xsd:element>
<xsd:element name="footnote">
  <xsd:complexType>
   <!--content model-->
   <xsd:attribute name="id" type="xsd:ID" use="required"/>
 </xsd:complexType>

...

给予

<quote ref="fn1">...</quote>
<footnote id="fn1">...</footnote>

所以引用必须有一个 ref 参数，在这种情况下它指向一个脚注

So quote must have a ref parameter, which in this case points to a footnote

嗯，上面的内容似乎是针对 DTD 的，但我发现它不起作用

Hmm would appear that the above was for DTD and doesn't work however I found this

真键表示

如果您曾尝试使用 DTD 描述具有复杂关系映射的关系数据库，您可能不得不使用 ID-IDREF 指向机制.例如，在两个实体通过关联表以多对多方式关联的结构中(例如，贷款申请中的借款人和资产)，简单的 XML 父子关系是不够的.但是，ID 和 IDREF 有其自身的弱点:ID 在整个文档中必须是唯一的，并且 IDREF 声明没有指定 IDREF 属性的实例必须引用的元素类型.XML Schema 提供了一种指定这些指向关系的方法，其方式与在关系数据库中声明外键关系的方式大致相同.例如，假设您有一个外键关系，您无法在我们的 XML 中使用简单的父子关系来表达它.您可以声明两个相关元素，如清单 3 所示:

If you have ever attempted to describe a relational database with a complex relationship map using a DTD, you've likely had to use the ID-IDREF pointing mechanism. For example, in a structure where two entities are related in a many-to-many way through a relating table (borrowers and assets on a loan application, for example), the simple XML parent-child relationship is insufficient. However, IDs and IDREFs have their own weaknesses: IDs must be unique across an entire document, and IDREF declarations do not specify the type of element an instance of the IDREF attribute must reference. XML Schema provides a way to specify these pointing relationships in much the same way that foreign-key relationships are declared in a relational database. For example, say you have a foreign-key relationship that you can't express using a simple parent-child relationship in our XML. You can declare the two related elements as in Listing 3:

<xsd:element name="rootElement">
  <xsd:complexType>
    <xsd:sequence>
      <xsd:element name="elementOne" maxOccurs="unbounded">
        <xsd:complexType>
          <xsd:attribute name="elementOneKey" type="integer" />
          <xsd:attribute name="elementOneDesc" type="text" />
        </xsd:complexType>
        <xsd:key name="elementOnePK">
          <xsd:selector xpath=".//elementOne"/>
          <xsd:field xpath="@elementOneKey"/>
        </xsd:key>
      </xsd:element>
      <xsd:element name="elementTwo" maxOccurs="unbounded">
        <xsd:complexType>
          <xsd:attribute name="elementTwoKey" type="integer" />
          <xsd:attribute name="elementOneKey" type="integer" />
          <xsd:attribute name="elementTwoDesc" type="text" />
        </xsd:complexType>
        <xsd:keyref name="elementOneFK" refer="elementOnePK">
          <xsd:selector xpath=".//elementTwo"/>
          <xsd:field xpath="@elementOneKey"/>
        </xsd:keyref>
      </xsd:element>
     </xsd:sequence>
   </xsd:complexType>
</xsd:element>

哪个更好，因为您可以正确链接 ID 和引用.

Which is even better as you can link id and reference properly.

有加分我正在学习东西.

Have a plus I'm learning stuff.

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