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子元素之间没有重复元素?

分类: 技术问答 • 2022-07-26 14:03:13
问题描述：

假设我有以下复杂类型:

Imagine I have the following complex types:

<xs:complexType name="pet">
    <xs:sequence>
        <xs:element name="add" type="xs:string" minOccurs="1" maxOccurs="unbounded" />
    </xs:sequence>
</xs:complexType>

<xs:complexType name="pets">
    <xs:sequence>
        <xs:element name="dogs" type="pet" minOccurs="0" maxOccurs="1" />
        <xs:element name="cats" type="pet" minOccurs="0" maxOccurs="1" />
        <xs:element name="hamsters" type="pet" minOccurs="0" maxOccurs="1" />
        <xs:element name="horses" type="pet" minOccurs="0" maxOccurs="1" />
    </xs:sequence>
</xs:complexType>

这意味着我可以像这样指定我的 xml:

This means that I can specify my xml like this:

<pets>
    <dogs>
        <add>Fido</add>
        <add>Pluto</add>
    </dogs>
    <cats>
        <add>Zorro</add>
        <add>Batman</add>
    </cats>
    <hamsters>
        <add>Bob</add>
    </hamsters>
    <horses>
        <add>Mr Horse</add>
    </horses>
</pets>

但我真正想做的是让我的架构要求至少定义一种 pet 类型.如果我将 pets 类型更改为:

But what I really would like to do is to have my schema demand that at least one of the pet types are defined. If I change my pets type to:

<xs:complexType name="pets">
    <xs:choice  minOccurs="1" maxOccurs="unbounded">
        <xs:element name="dogs" type="pet" />
        <xs:element name="cats" type="pet" />
        <xs:element name="hamsters" type="pet" />
        <xs:element name="horses" type="pet" />
    </xs:choice>
</xs:complexType>

这种方式使它起作用，因为现在要求我至少定义一个 pet.但是，现在可以拥有多个相同类型的 pet 元素.这是我想要避免的.以下内容现在有效:

This sort of makes it work because it is now demanded that I have at least one pet defined. However, it is now valid to have multiple pet elements of the same type. This is what I want to avoid. The following is now valid:

<pets>
    <dogs>
        <add>Pluto</add>
    </dogs>
    <dogs>
        <add>Fido</add>
    </dogs>
</pets>

那么，是否有可能每种类型只接受一个 pet 元素?

So, is it possible to only accept one pet element per type?

答

XSD 1.0

@5gon12eder建议:

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="pets">
    <xs:complexType>
      <xs:choice>
        <xs:sequence>
          <xs:element name="dogs" type="pet"/>
          <xs:element name="cats" type="pet" minOccurs="0"/>
          <xs:element name="hamsters" type="pet" minOccurs="0"/>
          <xs:element name="horses" type="pet" minOccurs="0"/>
        </xs:sequence>
        <xs:sequence>
          <xs:element name="cats" type="pet"/>
          <xs:element name="dogs" type="pet" minOccurs="0"/>
          <xs:element name="hamsters" type="pet" minOccurs="0"/>
          <xs:element name="horses" type="pet" minOccurs="0"/>
        </xs:sequence>
        <xs:sequence>
          <xs:element name="hamsters" type="pet"/>
          <xs:element name="dogs" type="pet" minOccurs="0"/>
          <xs:element name="cats" type="pet" minOccurs="0"/>
          <xs:element name="horses" type="pet" minOccurs="0"/>
        </xs:sequence>
        <xs:sequence>
          <xs:element name="horses" type="pet"/>
          <xs:element name="dogs" type="pet" minOccurs="0"/>
          <xs:element name="cats" type="pet" minOccurs="0"/>
          <xs:element name="hamsters" type="pet" minOccurs="0"/>
        </xs:sequence>
      </xs:choice>
    </xs:complexType>
  </xs:element>
  <xs:complexType name="pet">
    <xs:sequence>
      <xs:element name="add" type="xs:string" minOccurs="1" maxOccurs="unbounded" />
    </xs:sequence>
  </xs:complexType>
</xs:schema>

XSD 1.1

使用xs:assert保证pets至少有一个孩子:

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
           xmlns:vc="http://www.w3.org/2007/XMLSchema-versioning" vc:minVersion="1.1">

  <xs:element name="pets">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="dogs" type="pet" minOccurs="0"/>
        <xs:element name="cats" type="pet" minOccurs="0"/>
        <xs:element name="hamsters" type="pet" minOccurs="0"/>
        <xs:element name="horses" type="pet" minOccurs="0"/>
      </xs:sequence>
      <xs:assert test="*"/>
    </xs:complexType>
  </xs:element>

  <xs:complexType name="pet">
    <xs:sequence>
      <xs:element name="add" type="xs:string" minOccurs="1" maxOccurs="unbounded" />
    </xs:sequence>
  </xs:complexType>

</xs:schema>

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