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EMF Validation on EAttributes [message #897573]

Tue, 24 July 2012 10:47

Eclipse User

Hi,

Is there any way to perform an EMF validation on individual EAttribute's of an EObject?

What I want to be able to do is to add an error message to a text field which represents the name of my EObject (which is an EAttribute of it) when that name is empty.

I can think of a way of doing it which would involve adding a constraint method to the overall EObject and setting the Diagnostic I create in that method's source value to be something which I can recognise in the UI and match it up but that seems wrong to me.

What I would really like is to be able to call something like validateName() on the field and for it to validate it for me in the same way that calling validate() on the entire model validates the model.

Any ideas?

Thanks,
Simon

Re: EMF Validation on EAttributes [message #897578 is a reply to message #897573]

Tue, 24 July 2012 11:00

Eclipse User

Simon,

Comments below.

On 24/07/2012 4:47 PM, Simon Barnett wrote:
> Hi,
>
> Is there any way to perform an EMF validation on individual
> EAttribute's of an EObject?
Constraints can only be declared for an EClassifier. Of course it can
validate one or the attributes.
>
> What I want to be able to do is to add an error message to a text
> field which represents the name of my EObject (which is an EAttribute
> of it) when that name is empty.
You could also define an EDataType that wraps java.lang.String...
>
> I can think of a way of doing it which would involve adding a
> constraint method to the overall EObject and setting the Diagnostic I
> create in that method's source value to be something which I can
> recognise in the UI and match it up but that seems wrong to me.
It's the only direct way.
>
> What I would really like is to be able to call something like
> validateName() on the field
Of course fields don't have methods...
> and for it to validate it for me in the same way that calling
> validate() on the entire model validates the model.
If you define a constraint on the EClass, the generated validator will
have a method you can call directly.
>
> Any ideas?
>
> Thanks,
> Simon

Re: EMF Validation on EAttributes [message #897598 is a reply to message #897578]

Tue, 24 July 2012 12:31

Eclipse User

Hi Ed,

Yes, sorry, I didn't mean literally "call a method on the field" - I meant that I'd like to be able to call a method on the EAttribute to which the field is linked, if that makes sense. So maybe something like a validation method on the "name" attribute of the model which I can call when I know that the Text field is bound to that attribute.

Does that make sense?

I've already experimented with adding constraint methods to the overall EClass which represents the entire model and I *think* I've got that all working - it just seems hacky somehow to have to map the source of a diagnostic to a UI form element so that I can validate that particular attribute. But hey, if it's the only way, I suppose that's the only choice I have.

Re: EMF Validation on EAttributes [message #897601 is a reply to message #897598]

Tue, 24 July 2012 12:44

Eclipse User

Just to add to my reply, I think I'd be right in saying that in order to validate a field which was bound to the name attribute (for instance) I'd then be validating the entire model every time, no? This would be the case for the validation of any given field for any given attribute - the entire model would be validated?

Re: EMF Validation on EAttributes [message #897604 is a reply to message #897601]

Tue, 24 July 2012 13:01

Eclipse User

Simon,

Comments below.

On 24/07/2012 6:44 PM, Simon Barnett wrote:
> Just to add to my reply, I think I'd be right in saying that in order
> to validate a field which was bound to the name attribute (for
> instance) I'd then be validating the entire model every time, no?
For each constraint on an EClass, there is a generated method in the
validator that can you can call directly with the one instance object,
e.g., EcoreValidator.validateEClass_AtMostOneID. (Sorry it's a
metamodel example; hopefully that doesn't confuse the issue.)
> This would be the case for the validation of any given field for any
> given attribute - the entire model would be validated?

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