xs:key，为什么在键值不是键引用成员时验证通过？

Question

我希望定义一个关键约束在我的Xsd中。据我所知，使用xs:key应该将使用的值限制为引用值列表的成员。

假设我们正在使用示例Xsd，

<xs:schema
        xmlns:xs="http://www.w3.org/2001/XMLSchema"
        targetNamespace="namespace1"
        xmlns:r="namespace1"
        elementFormDefault="qualified">

  <xs:element name="root">
    <xs:complexType>
      <xs:sequence>

        <xs:element name="A" type="r:A" maxOccurs="unbounded">
          <xs:keyref name="dummy" refer="r:pNumKey">
            <xs:selector xpath="part"/>
            <xs:field xpath="@ref-number"/>
          </xs:keyref>
        </xs:element>

        <xs:element name="B" type="r:B"/>

      </xs:sequence>
    </xs:complexType>

    <xs:key name="pNumKey">
      <xs:selector xpath="r:B/r:part"/>
      <xs:field xpath="@key-number"/>
    </xs:key>

  </xs:element>

  <xs:complexType name="A">
    <xs:sequence>
      <xs:element name="part" maxOccurs="unbounded">
        <xs:complexType>
          <xs:simpleContent>
            <xs:extension base="xs:string">
              <xs:attribute name="ref-number" type="xs:integer"/>
            </xs:extension>
          </xs:simpleContent>
        </xs:complexType>
      </xs:element>
    </xs:sequence>
  </xs:complexType>

  <xs:complexType name="B">
    <xs:sequence>
      <xs:element name="part" maxOccurs="unbounded">
        <xs:complexType>
          <xs:simpleContent>
            <xs:extension base="xs:string">
              <xs:attribute name="key-number" type="xs:integer"/>
            </xs:extension>
          </xs:simpleContent>
        </xs:complexType>
      </xs:element>
    </xs:sequence>
  </xs:complexType>

</xs:schema>

样例XML：

<root xmlns="namespace1">
  <A>
    <!-- 
      if the ref-number is not equal to one of the key-number, 
      the validation will give error 
    -->
    <part ref-number="1"/>
  </A>
  <A>
    <!-- 
      if the ref-number is not equal to one of the key-number, 
      the validation will give error 
    -->
    <part ref-number="2"/>
  </A>
  <B>
    <part key-number="1"/>
    <part key-number="2"/>
    <part key-number="3"/>
  </B>
</root>

而且，需要进行一些简单的验证。

[TestMethod]
public void Test_Schema()
{
    string schemaFileName = @"sampleSchema.xsd";
    string xmlFileName = @"sampleXml.xml";
    XmlReaderSettings settings = new XmlReaderSettings
    {
        ValidationType = ValidationType.Schema,
        ValidationFlags = 
            XmlSchemaValidationFlags.ProcessInlineSchema |
            XmlSchemaValidationFlags.ProcessSchemaLocation | 
            XmlSchemaValidationFlags.ReportValidationWarnings,
    };
    settings.Schemas.Add (schema);
    settings.ValidationEventHandler += 
        (o, e) => { throw new Exception("CRASH"); };

    XmlSchema schema = 
        XmlSchema.Read (
        File.OpenText (schemaFileName), 
        (o, e) => { throw new Exception ("BOOM"); });

    XmlReader reader = XmlReader.Create (xmlFileName, settings);
    while (reader.Read ()) { }
}

当我使用不良值A/part[@ref-number]时，验证仍然成功，这是为什么？

<root xmlns="namespace1">
  <A>
    <!-- doesn't go CRASH BOOM bang! why not? :( -->
    <part ref-number="5"/>
  </A>
  <B>
    <part key-number="1"/>
    <part key-number="2"/>
    <part key-number="3"/>
  </B>
</root>

是否Xsd、Xml或验证中的任何一个或全部不正确？还是我误解了xs:key的预期目的？

- johnny g

Answer 1

通常情况下，经过一夜的休息和全新的视角，我在这个练习中发现了不少于2个错误。

1. 第一个错误是，验证身份约束是一个明确的过程，通过XmlReaderSettings.ValidationFlag设置的XmlSchemaValidationFlags.ProcessIdentityConstraints引入。
2. 第二个错误是，在msdn示例中模式存在错误，<xs:selector xpath="part"/>应该改为<xs:selector xpath="r:part"/>。

完整的工作样例如下：

<xs:schema
        xmlns:xs="http://www.w3.org/2001/XMLSchema"
        targetNamespace="namespace1"
        xmlns:r="namespace1"
        elementFormDefault="qualified">
  <xs:element name="root">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="A" type="r:A" maxOccurs="unbounded">
          <xs:keyref name="dummy" refer="r:pNumKey">
            <!-- without 'r:' below, key was not recognized, boo-urns msdn! -->
            <xs:selector xpath="r:part"/>
            <xs:field xpath="@ref-number"/>
          </xs:keyref>
        </xs:element>
        <xs:element name="B" type="r:B"/>
      </xs:sequence>
    </xs:complexType>
    <xs:key name="pNumKey">
      <xs:selector xpath="r:B/r:part"/>
      <xs:field xpath="@key-number"/>
    </xs:key>
  </xs:element>

  <xs:complexType name="A">
    <xs:sequence>
      <xs:element name="part" maxOccurs="unbounded">
        <xs:complexType>
          <xs:simpleContent>
            <xs:extension base="xs:string">
              <xs:attribute name="ref-number" type="xs:integer"/>
            </xs:extension>
          </xs:simpleContent>
        </xs:complexType>
      </xs:element>
    </xs:sequence>
  </xs:complexType>

  <xs:complexType name="B">
    <xs:sequence>
      <xs:element name="part" maxOccurs="unbounded">
        <xs:complexType>
          <xs:simpleContent>
            <xs:extension base="xs:string">
              <xs:attribute name="key-number" type="xs:integer"/>
            </xs:extension>
          </xs:simpleContent>
        </xs:complexType>
      </xs:element>
    </xs:sequence>
  </xs:complexType>
</xs:schema>

XML 示例

<root xmlns="namespace1">
  <A>
    <!-- goes CRASH BOOM bang! failure for the win! -->
    <part ref-number="5"/>
  </A>
  <B>
    <part key-number="1"/>
    <part key-number="2"/>
    <part key-number="3"/>
  </B>
</root>

简单的验证器

[TestMethod]
public void Test_Schema()
{
    string schemaFileName = @"sampleSchema.xsd";
    string xmlFileName = @"sampleXml.xml";

    XmlSchema schema = 
        XmlSchema.Read(
        File.OpenText(schemaFileName), 
        (o, e) => { throw new Exception("BOOM"); });

    XmlReaderSettings settings = new XmlReaderSettings
    {
        ValidationType = ValidationType.Schema,
        ValidationFlags = 
            XmlSchemaValidationFlags.ProcessInlineSchema | 
            XmlSchemaValidationFlags.ProcessSchemaLocation | 
            XmlSchemaValidationFlags.ReportValidationWarnings | 

            // d'oh! explicit flag for processing identity constraints!
            XmlSchemaValidationFlags.ProcessIdentityConstraints,
    };
    settings.Schemas.Add(schema);
    settings.ValidationEventHandler += 
        (o, e) => { throw new Exception("CRASH"); };

    XmlReader reader = XmlReader.Create(xmlFileName, settings);
    while (reader.Read()) { }
}

- johnny g

---

根据MSDN，ProcessIdentityConstraints默认启用。来自System.Xml.Schema的扩展方法XDocument.Load(inputXmlPath).Validate(schemas, null)运行良好。 - ilyaigpetrov

Answer 2

我想你应该使用ValidationEventHandler：

settings.ValidationEventHandler += new ValidationEventHandler (ValidationCallBack);

private static void ValidationCallBack (object sender, ValidationEventArgs args) {}

- Shrike

---

猜得不错，但是不对。仍然通过验证。不过我修改了我的帖子，包括在设置对象上添加一个明确的验证事件处理程序。 - johnny g