XML Schema How to Restrict Attribute by Enumeration

Question

I have the following XML Tag

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

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:

<xs:element name="price">     <xs:complexType>         <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:complexType> </xs:element> 

Answer 1

The numerical value seems to be missing from your price definition. Try the following:

<xs:simpleType name="curr">   <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:extension base="xs:decimal">               <xs:attribute name="currency" type="curr"/>             </xs:extension>         </xs:complexType> </xs:element> 

Answer 2

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>