如何在 XML 中声明属性 ID [英] How to declare an attribute ID in XML

问题描述

我正在写一些 XML 和 XSD 作为作业...在我的 XML 中，我有一个名为 a(不是实际名称)的标记和名为 id 的属性.我的部分 XML 如下所示:

I'm writing some XML and an XSD as an assignment... In my XML i have a tag called a ( not actual name) and attribute called id. Part of my XML is shown below:

    <a id="1">
    ...........
    </a>
    <a id="1">
    ............
    </a>

当我使用 XSD 进行验证时，它不会出现错误....

When I validate using XSD it doesn't give an error....

    <xsd:attribute name="id" type="xsd:string" />

我尝试使用 xsd:ID 作为属性 id 的数据类型，但它给了我一个错误；我无法弄清楚是什么问题.

I tried to use xsd:ID as a data type of attribute id but it gave me an error; I couldn't figure out what the problem is.

我该怎么做?

推荐答案

您应该重新使用 type="xsd:ID".除了确保该值是唯一的之外，它还允许您使用 xsd:IDREF 进行引用.

You should go back to using type="xsd:ID". What this does in addition to making sure that the value is unique is that it will also allow you to use xsd:IDREF for referencing.

当您尝试使用 xsd:ID 时遇到的错误是 ID 值必须以字母开头.如果您将 ID 更改为ID-1"/ID-2"或a1"/a2"之类的内容，它会正常工作.

The error you're getting when you try to use xsd:ID is that an ID value must start with a letter. If you change your ID's to something like "ID-1"/"ID-2" or "a1"/"a2", it will work fine.

示例架构:

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
  <xsd:element name="doc">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:element maxOccurs="unbounded" ref="a"/>
        <xsd:element maxOccurs="unbounded" ref="b"/>
      </xsd:sequence>
    </xsd:complexType>
  </xsd:element>
  <xsd:element name="a">
    <xsd:complexType>
      <xsd:simpleContent>
        <xsd:extension base="xsd:string">
          <xsd:attribute name="id" use="required" type="xsd:ID"/>
        </xsd:extension>
      </xsd:simpleContent>
    </xsd:complexType>
  </xsd:element>
  <xsd:element name="b">
    <xsd:complexType>
      <xsd:simpleContent>
        <xsd:extension base="xsd:string">
          <xsd:attribute name="idref" use="required" type="xsd:IDREF"/>
        </xsd:extension>
      </xsd:simpleContent>
    </xsd:complexType>
  </xsd:element>
</xsd:schema>

示例 XML:

<doc xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:noNamespaceSchemaLocation="Untitled1.xsd">
  <a id="ID-1">
    ...........
  </a>
  <a id="ID-2">
    ............
  </a>
  <b idref="ID-1"/>
</doc>

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