XML Schema How to Restrict Attribute by Enumeration

Question

I have the following XML Tag   lt price currency  euros  gt 20000 00 lt  price gt    How do I restrict the currency attribute to one the following    euros pounds dollars   AND the price to a double   I just get an error when I try to a type on both  here s what I ve got so far    lt xs element name  price  gt       lt xs complexType gt           lt xs attribute name  currency  gt               lt xs simpleType gt                   lt xs restriction base  xs string  gt                       lt xs enumeration value  pounds    gt                       lt xs enumeration value  euros    gt                       lt xs enumeration value  dollars    gt                   lt  xs restriction gt               lt  xs simpleType gt           lt  xs attribute gt       lt  xs complexType gt   lt  xs element gt

User · Answer

New answer to old question

None of the existing answers to this old question address the real problem.

The real problem was that xs:complexType cannot directly have a xs:extension as a child in XSD. The fix is to use xs:simpleContent first. Details follow...

Your XML,

<price currency="euros">20000.00</price>

will be valid against either of the following corrected XSDs:

Locally defined attribute type

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

  <xs:element name="price">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:decimal">
          <xs:attribute name="currency">
            <xs:simpleType>
              <xs:restriction base="xs:string">
                <xs:enumeration value="pounds" />
                <xs:enumeration value="euros" />
                <xs:enumeration value="dollars" />
              </xs:restriction>
            </xs:simpleType>
          </xs:attribute>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
</xs:schema>

Globally defined attribute type

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

  <xs:simpleType name="currencyType">
    <xs:restriction base="xs:string">
      <xs:enumeration value="pounds" />
      <xs:enumeration value="euros" />
      <xs:enumeration value="dollars" />
    </xs:restriction>
  </xs:simpleType>

  <xs:element name="price">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:decimal">
          <xs:attribute name="currency" type="currencyType"/>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
</xs:schema>

Notes

As commented by @Paul, these do change the content type of price from xs:string to xs:decimal, but this is not strictly necessary and was not the real problem.
As answered by @user998692, you could separate out the definition of currency, and you could change to xs:decimal, but this too was not the real problem.

The real problem was that xs:complexType cannot directly have a xs:extension as a child in XSD; xs:simpleContent is needed first.

A related matter (that wasn't asked but may have confused other answers):

How could price be restricted given that it has an attribute?

In this case, a separate, global definition of priceType would be needed; it is not possible to do this with only local type definitions.

How to restrict element content when element has attribute

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

  <xs:simpleType name="priceType">  
    <xs:restriction base="xs:decimal">  
      <xs:minInclusive value="0.00"/>  
      <xs:maxInclusive value="99999.99"/>  
    </xs:restriction>  
  </xs:simpleType>

  <xs:element name="price">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="priceType">
          <xs:attribute name="currency">
            <xs:simpleType>
              <xs:restriction base="xs:string">
                <xs:enumeration value="pounds" />
                <xs:enumeration value="euros" />
                <xs:enumeration value="dollars" />
              </xs:restriction>
            </xs:simpleType>
          </xs:attribute>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
</xs:schema>

User · Answer

lt xs element name  price  type  decimal  gt   lt xs attribute name  currency  type  xs string  value   euros pounds dollars     gt    lt  element gt     This would eliminate the need for enumeration completely  You could change type to double if required

User · Answer

you need to create a type and make the attribute of that type      lt xs simpleType name  curr  gt     lt xs restriction base  xs string  gt       lt xs enumeration value  pounds    gt       lt xs enumeration value  euros    gt       lt xs enumeration value  dollars    gt     lt  xs restriction gt   lt  xs simpleType gt    then      lt xs complexType gt       lt xs attribute name  currency  type  curr   gt   lt  xs complexType gt

User · Answer

The numerical value seems to be missing from your price definition  Try the following    lt xs simpleType name  curr  gt     lt xs restriction base  xs string  gt       lt xs enumeration value  pounds    gt       lt xs enumeration value  euros    gt       lt xs enumeration value  dollars    gt     lt  xs restriction gt   lt  xs simpleType gt      lt xs element name  price  gt           lt xs complexType gt               lt xs extension base  xs decimal  gt                 lt xs attribute name  currency  type  curr   gt               lt  xs extension gt           lt  xs complexType gt   lt  xs element gt

[xml] XML Schema How to Restrict Attribute by Enumeration

New answer to old question

Locally defined attribute type

Globally defined attribute type

Notes

How to restrict element content when element has attribute

Examples related to xml

Examples related to xsd