Re: Restricting attribute use from optional to required

OK, so let's say we get rid off this repeating of content model
declaration using named model group, see below.
There's still one place I'd like to fix - the enumeration of all
attributes from 'attributes' attributeGroup inside the
'parentWithReqLabelAttr' type declaration.

<xsd:attributeGroup name="attributes">
  <xsd:attribute name="label" type="xsd:string" />
  ...
</xsd:attributeGroup>

<xsd:group name="commonElements">
  <xsd:sequence>
      ...
  </xsd:sequence>
</xsd:group>

<xsd:complexType name="parent">
  <xsd:group ref="commonElements"/>
  <xsd:attributeGroup ref="attributes"/>
</xsd:complexType>

<xsd:complexType name="parentWithReqLabelAttr">
  <xsd:complexContent>
    <xsd:restriction base="parent">
      <xsd:group ref="commonElements"/>
      <xsd:attribute name="label" type="xsd:string" use="required"/>
      ... list all remaining attributes from 'attributes' group!!!
    </xsd:restriction>
  </xsd:complexContent>
</xsd:complexType>

<xsd:complexType name="derivedWithOptLabelAttr">
  <xsd:complexContent>
    <xsd:extension base="parent">
      <xsd:sequence>
        <xsd:element ref="style"/>
      </xsd:sequence>
      <xsd:attribute name="icon" type="xsd:string" use="optional"/>
    </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

<xsd:complexType name="derivedWithReqLabelAttr">
  <xsd:complexContent>
    <xsd:extension base="parentWithReqLabelAttr">
      <xsd:sequence>
        <xsd:element ref="parameter" minOccurs="0" maxOccurs="unbounded"/>
      </xsd:sequence>
      <xsd:attribute name="name" type="xsd:string" use="required"/>
    </xsd:extension>
  </xsd:complexContent>
</xsd:complexType>

I'd like to have there something like a restriction of attributeGroup,
either local or a global inside the type 'parentWithReqLabelAttr':

<xsd:attributeGroup name="attributesWithReqLabelAttr">
  <xsd:attributeGroup ref="attributes">
    <xsd:attribute ref="label" use="required"/>
  </xsd:attributeGroup>
</xsd:attributeGroup>

If this can be achieved then I would be able to add a new attribute to
the 'attributes' attributeGroup without changing the
'parentWithReqLabelAttr' type. However as far as I know there's no
such mechanism.

Jan Pridal

2009/8/17 Michael Kay <mike@saxonica.com>:
>> But it is then more than a little bit awkward - as I have to
>> add a new complexType that restricts the complexType 'parent'
>> and then within it I have to repeat all the stuff declared
>> the 'parent' and its parent types (by extension) etc.
>
> Yes, that's a particularly nasty feature of derivation by restriction.
>
> If you're only restricting the attributes, and not the content model, you
> can get around it by having both the base type and the derived type
> reference the same named model group.
>
> Regards,
>
> Michael Kay
> http://www.saxonica.com/
> http://twitter.com/michaelhkay
>
>

Received on Wednesday, 26 August 2009 07:23:34 UTC