RE: [xml-dev] extend two elements?

Hi Amy:

I find your question a bit confusing but tolerance of ambiguity is the hallmark of the good consultant, so here is a simple answer, based on what I think you most likely want to achieve.

Unless the business/application context prevents you, you can add grad_address to the data model of grad_student as a sub-element like this:

    <xsd:complexType name="grad_student">
          <xsd:complexContent>
             <xsd:extension base="student">
                <xs:sequence>

<xs:element ref="xyz:grad_address" maxOccurs="unbounded" />

</xs:sequence>

                <xsd:attribute name="name" type="xsd:string" use="required"/>

                <xsd:attribute name="grade" type="xsd:string" use="required"/>

              </xsd:extension>

</xsd:complexContent>
</xsd:complexType>

This says a grad_student must have one or more grad_addresses.

You literally extend types, not elements. But you can have multiple levels of derivation by extension. So if you really wanted to extend grad_address (which is already an extension of address) you could:

          <xsd:complexType name="graduate_address">
             <xsd:complexContent>
                <xsd:extension base="grad_address">
                   <xsd:attribute name="address_category" type="xsd:string" use="required"/>
                </xsd:extension>
             </xsd:complexContent>
          </xsd:complexType>
       <xsd:element name="graduate_address" type="xyz:graduate_address"/>

And then use graduate_address in my first example instead of grad_address so that you could use address_category to differentiate between campus addresses and home addresses, for instance.

[Examples not validated]

BTW, some places follow the naming convention of adding …type to the names of the complex types to avoid confusion with element names.

If this is not the answer you need, I will let the big guns take over

Cheers

Jack Lindsey

From: Amy Wong [mailto:amy_wanes@yahoo.com]
Sent: Tuesday October 31, 2006 2:59 PM
To: xml-dev@lists.xml.org
Subject: [xml-dev] extend two elements?

Hi,

I have an element called "grad_student" which extends "student". Now I want to extend "grad_address" element too since "grad_student" element needs address related info. Unfortunately I cannot merge address info from "grad_address" element into "grad_student" element. I am wondering how I can
extend another element when this element already extends a base element?

regards,

    <xsd:complexType name="grad_student">

          <xsd:complexContent>

             <xsd:extension base="student">

                <xsd:attribute name="name" type="xsd:string" use="required"/>

                <xsd:attribute name="grade" type="xsd:string" use="required"/>

             </xsd:extension>

 </xsd:complexContent>

       </xsd:complexType>

       <xsd:element name="grad_student" type="xyz:grad_student"/>

       

          <xsd:complexType name="grad_address">

             <xsd:complexContent>

                <xsd:extension base="address"> 

                   <xsd:attribute name="state" type="xsd:string" use="required"/>

                   <xsd:attribute name="zip_code" type="xsd:string" use="required"/>

                </xsd:extension>

             </xsd:complexContent>

          </xsd:complexType>

       <xsd:element name="grad_address" type="xyz:grad_address"/>

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