Re: Many-to-Many Join Table PK
Re: Many-to-Many Join Table PK
- Subject: Re: Many-to-Many Join Table PK
- From: Mike Schrag <email@hidden>
- Date: Tue, 16 Nov 2010 12:51:39 -0500
Probably entity modeler should have a validation check that if you check propagates pk, but the receiving end is not a pk, then it should be an error. As far as the tool not always doing the right thing, technically the tool did the right thing when it made his join entity, and then he later mucked with the entity structure making the current state invalid. I would say that the tool could pretty easily correct for this, though. I think where you see an argument for not using the tool, I see an argument for having our tools suck less.
ms
On Nov 16, 2010, at 12:32 PM, Ray Kiddy wrote:
>
> On Nov 16, 2010, at 6:32 AM, David Avendasora wrote:
>
>> Hi all,
>>
>> I have a Many-to-Many relationship and the join table does _not_ have a compound PK. It has a normal PK with a dataType of Long. The FKs that represent the to-One relationships on the join table are simply FKs and not part of the PK.
>>
>> I would like to flatten the toMany relationships, but when I add an object to the relationship and EOF tries to create a row in the join table it tries to create a compound PK for the join table, even though the Model is very clear as to what the PK is.
>>
>> Is this the normal EOF behavior to ignore the Model's PK settings for the join table and just assume that the PK is compound?
>>
>> I've always avoided flattened relationships because every time I try to use them I run into problems and give up and go back to regular relationships because it seems the work that flattened relationships save always gets offset by the limitations they impose (either that or my limitations of ability to use them properly).
>>
>> Dave _______________________________________________
>
> Riffing off a problem I had recently, I would guess that the tool (ever so helpfully) set the 'propagate primary key' on the relationships going into the join table. If that property is set on the two relationships, that may be enough to confuse things.
>
> If you use WOLips to create the many-to-many relationships and the join table, it did set the 'propagate primary key'. The tools may not always (as an aside to ms) do the right thing..... When I have created the scenario you describe, I never had problems, because I was creating the relationships manually and not setting 'propagate primary key'.
>
> Unfortunately, if one comes come up with the matrix of configurations for all the relationships and keys involved in a many-to-many relationship, there seems to be a lot of ways of configuring things. Some work and some do not.
>
> - ray
>
>
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