我可以根据子 Type 元素值验证多态 XML 元素吗? [英] Can I validate polymorphic XML elements based on a child Type element value?

问题描述

我想验证多态 Shape 元素，由 Type 子元素(not 属性)值区分.下面是兄弟 Circle 和 Rectangle Shape 元素.圆有一个 Radius 并且只有 1 个 Point.矩形没有 Radius 并且有 4 个 Point 元素:

I want to validate polymorphic Shape elements, differentiated by the Type child element (not attribute) value. Below are sibling Circle and Rectangle Shape elements. Circles have a Radius and only 1 Point. Rectangles don't have Radius and have 4 Point elements:

<?xml version="1.0" encoding="UTF-8" ?>
<Shapes>
  <Shape>
    <Type>Circle</Type>
    <ID>A1234</ID>
    <Label>This is round</Label>
    <Radius>5.4</Radius>
    <Points>
      <Point>
        <X>5.00</X>
        <Y>2.00</Y>
      </Point>
    </Points>
  </Shape>
  <Shape>
    <Type>Rectangle</Type>
    <ID>B4567</ID>
    <Label>This is not round</Label>
    <Points>
      <Point>
        <X>0.00</X>
        <Y>0.00</Y>
      </Point>
      <Point>
        <X>4.00</X>
        <Y>0.00</Y>
      </Point>
      <Point>
        <X>4.00</X>
        <Y>2.00</Y>
      </Point>
      <Point>
        <X>0.00</X>
        <Y>2.00</Y>
      </Point>
    </Points>
  </Shape>
</Shapes>

这是我希望做的事情的非功能模式:

Here's a NON-functional schema along the lines of what I was hoping to do:

  <xsd:simpleType name="ShapeTypeEnum">
    <xsd:restriction base="xsd:string">
      <xsd:enumeration value="Circle"/>
      <xsd:enumeration value="Rectangle"/>
    </xsd:restriction>
  </xsd:simpleType>

  <xsd:complexType name="ShapeBase">
    <xsd:sequence>
      <xsd:element name="Type" type="ShapeTypeEnum"/>
      <xsd:element name="ID" type="xsd:string"/>
      <xsd:element name="Label" type="xsd:string"/>
    </xsd:sequence>
  </xsd:complexType>

  <xsd:complexType name="Shape" type="Circle">
    <xsd:complexContent>
      <xsd:extension base="ShapeBase">
        <xsd:all>
          <xsd:element name="Radius" type="xsd:decimal"/>
          <xsd:element name="Points">
            <xsd:complexType>
              <xsd:sequence>
                <xsd:element minOccurs="1" maxOccurs="1" name="Point" type="Point"/>
              </xsd:sequence>
            </xsd:complexType>
          </xsd:element>
        </xsd:all>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>

  <xsd:complexType name="Shape" type="Rectangle">
    <xsd:complexContent>
      <xsd:extension base="ShapeBase">
        <xsd:all>
          <xsd:element name="Points">
            <xsd:complexType>
              <xsd:sequence>
                <xsd:element minOccurs="4" maxOccurs="4" name="Point" type="Point"/>
              </xsd:sequence>
            </xsd:complexType>
          </xsd:element>
        </xsd:all>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>

  <xsd:complexType name="Point">
    <xsd:all>
      <xsd:element name="X" type="xsd:decimal"/>
      <xsd:element name="Y" type="xsd:decimal"/>
    </xsd:all>
  </xsd:complexType>

行 和 不起作用.是否可以根据子元素(Type)的值来验证具有不同架构部分的同名元素?

The lines <xsd:complexType name="Shape" type="Rectangle"> and <xsd:complexType name="Shape" type="Circle"> don't work. Is it possible to validate identically named elements with different schema sections based on the value of a child Element (Type)?

推荐答案

在 XSD 1.0 中无法做到.在 XSD 1.1 中，它可以使用断言.

In XSD 1.0, it can't be done. In XSD 1.1, it can, using assertions.

尽管即使使用断言，也不是那么容易(如果 Type 是一个属性会容易得多).您需要定义一个内容模型，该模型实际上是针对不同形状的所有不同模型的联合(在此示例中您不能使用简单的 xs:choice，因为它会违反 UPA)，然后您需要定义像

Though even using assertions, it's not that easy (it would be much easier if Type were an attribute). You need to define a content model that's effectively a union of all the different models for different shapes (you can't use a simple xs:choice in this example because it would violate UPA), and then you need to define assertions like

<xs:assert test="exists(radius) = (type = 'Circle')"/>

<xs:assert test="count(points) = 4 or type != 'Rectangle'"/>

Altova、Saxon 和 Xerces 支持 XSD 1.1，但 Microsoft 模式处理器不支持.

XSD 1.1 is supported in Altova, Saxon, and Xerces, but not for example by the Microsoft schema processor.

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