xsd extension base element with attributes

Question

Suppose i have got schema

 <xs:complexType name="superType">

        <xs:sequence>
            <xs:element type="s:itemType" name="item" maxOccurs="unbounded" minOccurs="1">
            </xs:element>
        </xs:sequence>

        <xs:attribute type="s:stringNameType" name="name" use="required"/>
        <xs:attribute type="s:extraType" name="extra" use="optional" default="ALL"/>

    </xs:complexType>

and my next element:

<xs:complexType name="elegantType">
        <xs:simpleContent>
            <xs:extension base="xs:string">
                <xs:attribute type="s:stringNameType" name="name" use="required"/>
                <xs:attribute type="s:extraType" name="extra" use="optional" default="ALL"/>

            </xs:extension>
        </xs:simpleContent>
    </xs:complexType>

As you can see elegantType and superType have got the same attribute :

<xs:attribute type="s:stringNameType" name="name" use="required"/>
<xs:attribute type="s:extraType" name="extra" use="optional" default="ALL"/>

Its possible to create base type for that element using extension?

I try define base type but i have got error : The content type of a derived type and that of its base must both be mixed or both be element-only. Type 'superType' is element only, but its base type is not.

This is what i try to do :

            <xs:element type="s:itemType" name="item" maxOccurs="unbounded" minOccurs="1">
            </xs:element>
        </xs:sequence>
        </xs:extension>
    </xs:complexContent>


   <!-- <xs:attribute type="s:stringNameType" name="name" use="required"/>
    <xs:attribute type="s:extraType" name="extra" use="optional" default="ALL"/>-->

</xs:complexType>

<xs:complexType name="resourceBase" mixed="true">

    <xs:simpleContent>
        <xs:extension base="xs:string">
            <xs:attribute type="s:stringNameType" name="name" use="required"/>
            <xs:attribute type="s:extraType" name="extra" use="optional" default="ALL"/>

        </xs:extension>
    </xs:simpleContent>

</xs:complexType>

My problem is that i have got many element and most of them have got the same attribute. And i need create base element

Answer 1

If you have many elements with repeating attributes, you can use declare them in attribute groups and reuse the attributeGroup object in several elements:

In your schema you can declare a group like this:

<xs:attributeGroup name="attributes">
    <xs:attribute type="s:stringNameType" name="name" use="required"/>
    <xs:attribute type="s:extraType" name="extra" use="optional" default="ALL"/>
</xs:attributeGroup>

And then just add it in the place where you would add your attributes:

<xs:complexType name="superType">
    <xs:sequence>...</xs:sequence>
    <xs:attributeGroup ref="attributes"/>
</xs:complexType>

<xs:complexType name="elegantType">
    <xs:simpleContent>
        <xs:extension base="xs:string">
            <xs:attributeGroup ref="attributes"/>
        </xs:extension>
    </xs:simpleContent>
</xs:complexType>