how to do simple type extension with restriction?

[scorpion]

I have a simple type like this:

<xs:simpleType name="SizeType">
<xs:restriction base="xs:token">
<xs:enumeration value="small"/>
<xs:enumeration value="medium"/>
<xs:enumeration value="large"/>
<xs:enumeration value="xlarge"/>
</xs:restriction>
</xs:simpleType>

Now, I need to have an id attribute to that, so I'm trying to make it a complex type by extending to

<xs:complexType name="SizeType">
<xs:simpleContent>
<xs:extension base="xs:token">
....
</xs:extension>
</xs:simpleContent>
</xs:complexType>

Now, I'm stuck. How do I change that to a complex type, with the enumeration there? Better, is there a way to give an id to a simpleType, without changing it to a complexType, as the complexType is, er..., complex for such simple thing?

TIA.

 

[Martin Honnen]

I have a simple type like this:

<xs:simpleType name="SizeType">
<xs:restriction base="xs:token">
<xs:enumeration value="small"/>
<xs:enumeration value="medium"/>
<xs:enumeration value="large"/>
<xs:enumeration value="xlarge"/>
</xs:restriction>
</xs:simpleType>

Now, I need to have an id attribute to that, so I'm trying to make it a complex type by extending to

<xs:complexType name="SizeType">
<xs:simpleContent>
<xs:extension base="xs:token">
....
</xs:extension>
</xs:simpleContent>
</xs:complexType>

Now, I'm stuck. How do I change that to a complex type, with the enumeration there? Better, is there a way to give an id to a simpleType, without changing it to a complexType, as the complexType is, er..., complex for such simple thing?

As soon as you want an element to have an attribute you need a complex type for it, you can only use a simple type if the element has only text data as its content and no child elements and no attributes. As for your example it is not quite clear what you want to have, if you want to have an element with its content being of your SizeType and an additional ID attribute then the schema is

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

<xs:simpleType name="SizeType">
<xs:restriction base="xs:token">
<xs:enumeration value="small"/>
<xs:enumeration value="medium"/>
<xs:enumeration value="large"/>
<xs:enumeration value="xlarge"/>
</xs:restriction>
</xs:simpleType>

<xs:complexType name="SizeIdType">
<xs:simpleContent>
<xs:extension base="SizeType">
<xs:attribute name="id" type="xs:ID" />
</xs:extension>
</xs:simpleContent>
</xs:complexType>

<xs:element name="size" type="SizeIdType" />

</xs:schema>

and an example document is

<?xml version="1.0" encoding="UTF-8"?>
<size xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="test20040424Xsd.xml" id="theSize">medium</size>

 

[scorpion]

As soon as you want an element to have an attribute you need a complex type for it, you can only use a simple type if the element has only text data as its content and no child elements and no attributes. As for your example it is not quite clear what you want to have, if you want to have an element with its content being of your SizeType and an additional ID attribute then the schema is

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

<xs:simpleType name="SizeType">
<xs:restriction base="xs:token">
<xs:enumeration value="small"/>
<xs:enumeration value="medium"/>
<xs:enumeration value="large"/>
<xs:enumeration value="xlarge"/>
</xs:restriction>
</xs:simpleType>

<xs:complexType name="SizeIdType">
<xs:simpleContent>
<xs:extension base="SizeType">
<xs:attribute name="id" type="xs:ID" />
</xs:extension>
</xs:simpleContent>
</xs:complexType>

<xs:element name="size" type="SizeIdType" />

</xs:schema>

and an example document is

<?xml version="1.0" encoding="UTF-8"?>
<size xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="test20040424Xsd.xml" id="theSize">medium</size>

Thanks, I got it.

Is there any reason why attributes are not allowed on simpleType? There are a lot of cases where I can have very simple schema if I can have attributes directly on simpleType.

 

[Martin Honnen]

Is there any reason why attributes are not allowed on simpleType? There are a lot of cases where I can have very simple schema if I can have attributes directly on simpleType.

If XML schema only used types to type element content it might make sense but you can also type attributes and what should be the meaning of a schema where a simple type is defined which includes an attribute and then that type is assigned to an attribute elsewhere? Clearly there needs to be a distinction between types that can be applied to attributes and elements (which are the simple types) and those types that can only be applied to elements (which are the complex types)

 

[C. M. Sperberg-McQueen]

Is there any reason why attributes are not allowed on simpleType? There are a lot of cases where I can have very simple schema if I can have attributes directly on simpleType.

If you defined a simple type T as taking the
attributes foo (integer) and bar (string), what
would / should happen when you declare an
attribute as having type T?

I hope this helps.

-C. M. Sperberg-McQueen
World Wide Web Consortium