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Re: Question on id constraints

• From: Eddie Robertsson <eddie@a...>
• To: "Anderson, John" <John@B...>, Xml-Dev <xml-dev@l...>
• Date: Wed, 01 Aug 2001 10:25:15 +1000

Let me see if I can shed some light on the key, unique and keyref issue.

I'm trying to decipher the schema spec on identity contstraint validity, but perhaps someone can save me a few hours and a few aspirin.

If I have:
<keyref name="ref" refers="pk" > ...

1. Is the key "pk" required to be defined physically earlier in the schema file (I would have thought not)

<xs:element name="root">

   <xs:element name="sub" type="whatever">
      <xs:key name="key">
         <xs:selector xpath="key"/>
         <xs:field xpath="@id"/>
      </xs:key>
   </xs:element>

   <xs:keyref name="keyref" refer="key">
      <xs:selector xpath="keyref"/>
      <xs:field xpath="@ref"/>
   </xs:keyref>

</xs:element>

The scoping element for the key declaration is a descendant of the scoping element for the keyref declaration.

However this is not allowed:

<xs:element name="root">

   <xs:element name="sub" type="whatever">
      <xs:keyref name="keyref" refer="key">
         <xs:selector xpath="keyref"/>
         <xs:field xpath="@ref"/>
      </xs:keyref>
   </xs:element>

   <xs:key name="key">
      <xs:selector xpath="key"/>
      <xs:field xpath="@id"/>
   </xs:key>

</xs:element>

2. Is pk required to be defined on the same element as ref, or on a descendant or anscetor of it, or just anywhere in the same schema?

Cheers,
/Eddie
 

• References:
  • Question on id constraints
    • From: "Anderson, John" <John@B...>

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