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Class Identity [message #377187]

Fri, 09 June 2006 16:18

Eclipse User

Originally posted by: pedram.corticon.com

Does EMF intend for only a single EAttribute of an EClass to have its ID
property set to true? If more than one EAttribute has its ID property set
to true, does this mean that the combination of the two forms a composite
key for the EClass?

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Re: Class Identity [message #377189 is a reply to message #377187]

Fri, 09 June 2006 17:22

Ed Merks

Messages: 33140
Registered: July 2009

Senior Member

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Pedram,

Please direct EMF questions to the EMF newsgroup. Yes, when we
implement 75933 <https://bugs.eclipse.org/bugs/show_bug.cgi?id=75933>,
which we are working on now for the next release, we will validate that
there is at most one attribute with isID true (just as XML Schema
restricts there to be at most one element/attribute of type xsd:ID). In
119586 <https://bugs.eclipse.org/bugs/show_bug.cgi?id=119586> there is a
patch for changes to Ecore that would allow an EReference to specify
which EAttributes of the referenced EClass represent a key with respect
to that particular reference; this would allow us to generate fragment
paths such as //@eNamedElement[name='xyz'] that are based on keys rather
than on position.

Pedram Abrari wrote:
> Does EMF intend for only a single EAttribute of an EClass to have its ID
> property set to true? If more than one EAttribute has its ID property set
> to true, does this mean that the combination of the two forms a composite
> key for the EClass?
>
>
>

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Pedram, 
 
Please direct EMF questions to the EMF newsgroup.  Yes, when we
implement <a href="https://bugs.eclipse.org/bugs/show_bug.cgi?id=75933">75933</a>,
which we are working on now for the next release, we will validate that
there is at most one attribute with isID true (just as XML Schema
restricts there to be at most one element/attribute of type xsd:ID). In
<a href="https://bugs.eclipse.org/bugs/show_bug.cgi?id=119586">119586</a>
there is a patch for changes to Ecore that would allow an EReference to
specify which EAttributes of the referenced EClass represent a key with
respect to that particular reference; this would allow us to generate
fragment paths such as //@eNamedElement[name='xyz'] that are based on
keys rather than on position. 
 
Pedram Abrari wrote:
<blockquote cite="mide6c70g$525$1@utils.eclipse.org" type="cite">
<pre wrap="">Does EMF intend for only a single EAttribute of an EClass to have its ID
property set to true? If more than one EAttribute has its ID property set
to true, does this mean that the combination of the two forms a composite
key for the EClass?

</pre>
</blockquote>
 
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Ed Merks
Professional Support: https://www.macromodeling.com/

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