How to define multiple elements in XML Schema with the same name and different attribute value allowed?

问题

I would like to create XML Schema for this chunk of xml, I would like to restrict the values of "name" attribute, so that in output document on and only one instance of day is allowed for each week day:

<a>
  <day name="monday" />
  <day name="tuesday" />
  <day name="wednesday" />
</a>

I have tried to use this:

 <xs:complexType name="a">
  <xs:sequence>
    <xs:element name="day" minOccurs="1" maxOccurs="1">
      <xs:complexType>
        <xs:attribute name="name" use="required">
          <xs:simpleType>
            <xs:restriction base="xs:string">
              <xs:enumeration value="monday" />
            </xs:restriction>
          </xs:simpleType>
        </xs:attribute>
      </xs:complexType>
    </xs:element>
    <xs:element name="day" minOccurs="1" maxOccurs="1">
      <xs:complexType>
        <xs:attribute name="name" use="required">
          <xs:simpleType>
            <xs:restriction base="xs:string">
              <xs:enumeration value="tuesday" />
            </xs:restriction>
          </xs:simpleType>
        </xs:attribute>
      </xs:complexType>
    </xs:element>
  </xs:sequence>
</xs:complexType>

but XML Schema validator in eclipse says error "Multiple elements with name 'day', with different types, appear in the model group.".

Is there any other way?

回答1:

You need something like this:

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
  <xs:element name="a">
    <xs:complexType>
      <xs:sequence>
        <xs:element maxOccurs="unbounded" ref="day"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="day">
    <xs:complexType>
      <xs:attribute name="name" use="required">
        <xs:simpleType>
            <xs:restriction base="xs:string">
                <xs:enumeration value="monday"/>
                <xs:enumeration value="tuesday"/>
                <xs:enumeration value="wednesday"/>
            </xs:restriction>
        </xs:simpleType>
        </xs:attribute>
    </xs:complexType>
  </xs:element>
</xs:schema>

回答2:

In order to satisfy the at-most-once constraint described in the original question, you need to use a xs:unique element in your schema.

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

  <xs:element name="a">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="day" maxOccurs="7" minOccurs="1">
          <xs:complexType>
            <xs:attribute name="name" use="required">
              <xs:simpleType>
                <xs:restriction base="xs:string">
                  <xs:pattern value="(mon|tues|wednes|thurs|fri|satur|sun)day"/>
                </xs:restriction>
              </xs:simpleType>
            </xs:attribute>
          </xs:complexType>
          <xs:unique name="eachDayAtMostOnce">
            <xs:selector xpath="day"/>
            <xs:field xpath="@name"/>
          </xs:unique>
        </xs:element>
      </xs:sequence>
    </xs:complexType>
  </xs:element>

</xs:schema>

回答3:

Have you considered something like this? (i.e. day is a type, and the elements are named after the days of the week)

<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:complexType name="day" />
  <xs:element name="a">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="monday" maxOccurs="1" minOccurs="0" type="day" />
        <xs:element name="tuesday" maxOccurs="1" minOccurs="0" type="day" />
        <xs:element name="wednesday" maxOccurs="1" minOccurs="0" type="day" />
      </xs:sequence>
    </xs:complexType>
  </xs:element>
</xs:schema>

回答4:

Try this:

<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="a">
    <xs:complexType>
        <xs:sequence>
            <xs:element maxOccurs="unbounded" name="day">
                <xs:complexType>
                    <xs:attribute name="atrib" type="xs:string" use="required" />
                </xs:complexType>
            </xs:element>
        </xs:sequence>
    </xs:complexType>
</xs:element>

I think the maxOccurs="unbounded" is what you need.

回答5:

Use choice instead of sequence

By that way u can have only day element one's in a element

And for name attribute use ref attribute and reference it with enumeration

来源：https://stackoverflow.com/questions/177945/how-to-define-multiple-elements-in-xml-schema-with-the-same-name-and-different-a

标签

xsd