我有一个包含问题结构的 XML 文件格式:

<question id="q101">
  <text>Do you like the color red?</text>
  <answer>yes</answer>
  <answer>no</answer>
</question>
<question id="q102">
  <text>What is your favorite color?</text>
  <answer>red</answer>
  <answer>blue</answer>
  <answer>white</answer>
  <answer>yellow</answer>
</question>

我在同一个文件中也有来自多个用户的回复。

<user id="bob">
  <response questionIdRef="q101">yes</response>
  <response questionIdRef="q102">white</response>
</user>
<user id="jane">
  <response questionIdRef="q101">no</response>
  <response questionIdRef="q102">blue</response>
</user>

我已经在 xml 中为问题 Id 定义了一个键和一个 keyref 元素:

<xsd:key name="questionId">
  <xsd:selector xpath=".//question" />
  <xsd:field xpath="@id" />
</xsd:key>
<xsd:keyref name="responseQuestionIdKeyRef" refer="questionId">
  <xsd:selector xpath=".//response" />
  <xsd:field xpath="@questionIdRef" />
</xsd:keyref>

我现在想做的是让架构验证用户对某个问题的回答值实际上是引用问题中提供的答案。我尝试使用以下键和 keyref 来执行此操作，但它只会识别第一个答案，所有其他答案都不会被识别为有效:

<xsd:key name="answerValue">
  <xsd:selector xpath=".//question" />
  <xsd:field xpath="@id" />
  <xsd:field xpath=".//answer/value" />
</xsd:key>
<xsd:keyref name="validAnswer" refer="answerValue">
  <xsd:selector xpath=".//response" />
  <xsd:field xpath="@questionIdRef" />
  <xsd:field xpath="." />
</xsd:keyref>

我得到的确切错误是:

The field 'answer' is expecting at most one value.

我应该注意，我正在使用 C# XML 验证器。

为了完整起见，下面是我所指的完整架构和 xml 实例: 架构:

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <xsd:element name="survey">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:element name="user" maxOccurs="unbounded">
          <xsd:complexType>
            <xsd:sequence>
              <xsd:element name="response" maxOccurs="unbounded">
                <xsd:complexType>
                  <xsd:simpleContent>
                    <xsd:extension base="xsd:string">
                      <xsd:attribute name="questionIdRef" type="xsd:string" use="required" />
                    </xsd:extension>
                  </xsd:simpleContent>
                </xsd:complexType>
              </xsd:element>
            </xsd:sequence>
            <xsd:attribute name="id" type="xsd:string" use="required" />
          </xsd:complexType>
        </xsd:element>
        <xsd:element name="question" maxOccurs="unbounded">
          <xsd:complexType>
            <xsd:sequence>
              <xsd:element name="text" type="xsd:string" />
              <xsd:element name="answer" maxOccurs="unbounded" type="xsd:string"/>
            </xsd:sequence>
            <xsd:attribute name="id" type="xsd:string" use="required" />
          </xsd:complexType>
          <xsd:unique name="uniqueAnswer">
            <xsd:selector xpath=".//answer" />
            <xsd:field xpath="@value" />
          </xsd:unique>
        </xsd:element>
      </xsd:sequence>
    </xsd:complexType>
    <!--

    <xsd:key name="questionId">
      <xsd:selector xpath=".//question" />
      <xsd:field xpath="@id" />
    </xsd:key>
    <xsd:keyref name="responseQuestionIdKeyRef" refer="questionId">
      <xsd:selector xpath=".//response" />
      <xsd:field xpath="@questionIdRef" />
    </xsd:keyref>

    -->
    <xsd:key name="answerValue">
      <xsd:selector xpath=".//question" />
      <xsd:field xpath="@id" />
      <xsd:field xpath=".//answer" />
    </xsd:key>
    <xsd:keyref name="validAnswer" refer="answerValue">
      <xsd:selector xpath=".//response" />
      <xsd:field xpath="@questionIdRef" />
      <xsd:field xpath="." />
    </xsd:keyref>
    <xsd:unique name="uniqueUserId">
      <xsd:selector xpath=".//user" />
      <xsd:field xpath="@id" />
    </xsd:unique>
  </xsd:element>
</xsd:schema>

示例 XML 实例:

<?xml version="1.0" encoding="utf-8"?>
<survey>
  <user id="bob">
    <response questionIdRef="q101">yes</response>
    <response questionIdRef="q102">white</response>
  </user>
  <user id="jane">
    <response questionIdRef="q101">no</response>
    <response questionIdRef="q102">blue</response>
  </user>
  <question id="q101">
    <text>Do you like the color red?</text>
    <answer>yes</answer>
    <answer>no</answer>
  </question>
  <question id="q102">
    <text>What is your favorite color?</text>
    <answer>red</answer>
    <answer>blue</answer>
    <answer>white</answer>
    <answer>yellow</answer>
  </question>
</survey>

最佳答案

好的，我发现了与我的问题相关的问题 ( XSD key/keyref: hierarchical key structure)。这个问题也没有可接受的答案。

这似乎是 XML Schema 技术的局限性。我决定重新排序模式，将用户的回答放在问题下。响应将指向用户。

下面是示例 XML 实例:

<?xml version="1.0" encoding="utf-8"?>
<survey>
  <user id="bob" />
  <user id="jane" />
  <question id="q101">
    <text>Do you like the color red?</text>
    <answer>yes</answer>
    <answer>no</answer>
    <response userIdRef="bob">yes</response>
    <response userIdRef="jane">no</response>
  </question>
  <question id="q102">
    <text>What is your favorite color?</text>
    <answer>red</answer>
    <answer>blue</answer>
    <answer>white</answer>
    <answer>yellow</answer>
    <response userIdRef="bob">white</response>
    <response userIdRef="jane">blue</response>
  </question>
</survey>

这是我使用的架构:

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <xsd:element name="survey">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:element name="user" maxOccurs="unbounded">
          <xsd:complexType>
            <xsd:attribute name="id" type="xsd:string" use="required" />
          </xsd:complexType>
        </xsd:element>
        <xsd:element name="question" maxOccurs="unbounded">
          <xsd:complexType>
            <xsd:sequence>
              <xsd:element name="text" type="xsd:string" />
              <xsd:element name="answer" maxOccurs="unbounded" type="xsd:string"/>
              <xsd:element name="response" maxOccurs="unbounded">
                <xsd:complexType>
                  <xsd:simpleContent>
                    <xsd:extension base="xsd:string">
                      <xsd:attribute name="userIdRef" type="xsd:string" use="required" />
                    </xsd:extension>
                  </xsd:simpleContent>
                </xsd:complexType>
              </xsd:element>
            </xsd:sequence>
            <xsd:attribute name="id" type="xsd:string" use="required" />
          </xsd:complexType>
          <xsd:key name="validAnswerKey">
            <xsd:selector xpath=".//answer" />
            <xsd:field xpath="." />
          </xsd:key>
          <xsd:keyref name="responseValidAnswerKeyRef" refer="validAnswerKey">
            <xsd:selector xpath=".//response" />
            <xsd:field xpath="." />
          </xsd:keyref>
        </xsd:element>
      </xsd:sequence>
    </xsd:complexType>
    <xsd:key name="userIdKey">
      <xsd:selector xpath=".//user" />
      <xsd:field xpath="@id" />
    </xsd:key>
    <xsd:keyref name="userResponse" refer="userIdKey">
      <xsd:selector xpath=".//response" />
      <xsd:field xpath="@userIdRef" />
    </xsd:keyref>
  </xsd:element>
</xsd:schema>

关于具有多个字段的 XML 模式键，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/1348753/