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using UUIDs in FragmentProvider [message #1130203]

Wed, 09 October 2013 06:06

Eclipse User

Hi,

I'm referencing EObject from non-Xtext (EMF-based) models.

I've read the following section in the documentation.
http://www.eclipse.org/Xtext/documentation.html#fragmentProvider

Could anyone give me insights on how to use UUIDs. In order to return the uuid of the EObject in the getFragment() method.

Many thanks in advance,
Benoît

Re: using UUIDs in FragmentProvider [message #1130270 is a reply to message #1130203]

Wed, 09 October 2013 07:30

Eclipse User

Hi I don't get your point if you want to reference non Xtext models
you have to implement a iresourceserviceprovider

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Re: using UUIDs in FragmentProvider [message #1130280 is a reply to message #1130270]

Wed, 09 October 2013 07:47

Eclipse User

Hi Christian,

actually I think this is the other way around. I have a non-xtext model in which I reference xtext EObjects.

This is the exact topic of the section "Fragment Provider (Referencing Xtext Models From Other EMF Artifacts)" in the Xtext documentation.

In the xtext doc it is mentioned the following "[...] With an XMI or other binary-like serialization it is also common and possible to use UUIDs [...]"

So in the doc, it says it is common and possible to use UUIDs but I don't have any clue on how to get started.

My question is :

How do I setup my DSL to use UUIDs in my DSL's fragment provider ?

Re: using UUIDs in FragmentProvider [message #1130281 is a reply to message #1130280]

Wed, 09 October 2013 07:48

Eclipse User

Sorry I have no idea on that

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Re: using UUIDs in FragmentProvider [message #1130285 is a reply to message #1130280]

Wed, 09 October 2013 07:53

Eclipse User

BTW the docs indicates you can use the fragment provider to identify
objects by a "business key" and not a real uuid. If you want so you
would have to implement the stuff yourself ....(I doubt this is
impossible besides e.g. hashing business keys)

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Re: using UUIDs in FragmentProvider [message #1130337 is a reply to message #1130280]

Wed, 09 October 2013 08:59

Eclipse User

Benoit,

The fragment provider would need to compute the fragment value from
information available in your Xtext-based model, so unless your
Xtext-based model somehow specifies UUIDs in the syntax, I don't think
this is possible. After all, while something like an XMIResourceImpl
can assign UUIDs automatically, those UUIDs are part of the
serialization of the model, so if you wanted something similar for
Xtext, there too, the UUIDs or whatever information you want to use for
the fragment would need to be part of the serialization...

On 09/10/2013 1:47 PM, Benoit Ries wrote:
> Hi Christian,
>
> actually I think this is the other way around. I have a non-xtext
> model in which I reference xtext EObjects.
>
> This is the exact topic of the section "Fragment Provider (Referencing
> Xtext Models From Other EMF Artifacts)" in the Xtext documentation.
>
> In the xtext doc it is mentioned the following "[...] With an XMI or
> other binary-like serialization it is also common and possible to use
> UUIDs [...]"
>
> So in the doc, it says it is common and possible to use UUIDs but I
> don't have any clue on how to get started.
>
> My question is :
>
> How do I setup my DSL to use UUIDs in my DSL's fragment provider ?

Re: using UUIDs in FragmentProvider [message #1130389 is a reply to message #1130203]

Wed, 09 October 2013 10:04

Eclipse User

thanks for your answers.

Re: using UUIDs in FragmentProvider [message #1138663 is a reply to message #1130285]

Tue, 15 October 2013 04:33

Eclipse User

Hi Christian, Ed,

I'm following up on this post.

I started the implementation for this issue on giving uuids values to my EObjects. I have added a new attribute "uuid" to my EObject in my DSL's metamodel.

For now what I do is the code below. But the problem is that the value of uuid is not stable and is regenerated every time I access it.

So I guess that the value should not be initialized in this method.

My question is => Where can I initialize the uuid values of my EObjects ??

***
public String getFragment(EObject obj, Fallback fallback) {
String uuid = "";
if (obj instanceof PackageDeclaration) {
PackageDeclaration packageDeclaration = (PackageDeclaration) obj;
if (packageDeclaration.getUuid() == null
|| (packageDeclaration.getUuid() != null
&& packageDeclaration.getUuid().equals(""))) {
packageDeclaration.setUuid(EcoreUtil.generateUUID());
}
uuid = packageDeclaration.getUuid();
}
return !uuid.equals("")? uuid : fallback.getFragment(obj);
}
***

[Updated on: Tue, 15 October 2013 04:41] by Moderator

Re: using UUIDs in FragmentProvider [message #1138719 is a reply to message #1138663]

Tue, 15 October 2013 05:23

Eclipse User

Hi as said before: this is not possible. The ids have to be
(syntactically) part of the model or derived from it

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Re: using UUIDs in FragmentProvider [message #1138735 is a reply to message #1138719]

Tue, 15 October 2013 05:40

Eclipse User

I understand that ids have to be syntactically part of the model.

I have just switched to a manually maintained metamodel, in which I added an uuid attribute to some of my DSL's EObjects.

Do we understand each other ?

Re: using UUIDs in FragmentProvider [message #1138747 is a reply to message #1138735]

Tue, 15 October 2013 05:49

Eclipse User

You have to write in your model file

Element myelement id yourid

--
Need training, onsite consulting or any other kind of help for Xtext?
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Re: using UUIDs in FragmentProvider [message #1140216 is a reply to message #1138747]

Wed, 16 October 2013 03:52

Eclipse User

thanks for your very clear answer.
I thought manually maintaining my metamodel would be a workaround and now understand it is not. Sad

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