Question

I have defined the following two types in my XSD-file:

<complexType name="primitive">
  <attribute name="seq_num" type="int"/>
  <element name="prim_to" type="int"/>
</complexType>


<complexType name="configdata">
  <sequence>
    <element name="enable" type="boolean"/>
    <element name="type" default="int"/>
   </sequence>
</complexType>

Both types are used in a number of definitions, i.e. I would rather not change these them. I would like to define a new element set which extends primitive and contains all sub-elements of configdata. The XML-file for this element would look like this (please note, that enable and type are at the same level as prim_to):

<set seq_num="1234">
  <prim_to>22</prim_to>
  <enable>true<enable>
  <type>42</type>
</set>

I could declare set the following way:

<element name="set">
  <complexType>
    <complexContent>
      <extension base="primitive">
        <sequence>
          <element name="config" type="configdata"/>
        </sequence>
      </extension>
    </complexContent>
  </complexType>
</element>

In this case the XML-file would look like this:

<set seq_num="1234">
  <prim_to>22</prim_to>
  <config>
    <enable>true<enable>
    <type>42</type>
  </config>
</set>

My challenge is to define set in such a way that it extends primitive and contains all sub-elements of configdata – but does not contain an element of the type configdata. Basically for the XML-file above it is a question of not having the two ‘config’-tags. Is this possible in XSD? I would highly appreciate any hints.

Thanks in Advance,
Witek

Answer 1

A type can only extend a single other one (in other words, there is no multiple inheritance). So, your set element can extend configdata (with xsd:extension) and have additional elements, or it can extend another type and you could copy configdata elements to extend it. You can use groups to avoid redundancy.