Re: Confused with delete rules in EntityModeler
Re: Confused with delete rules in EntityModeler
- Subject: Re: Confused with delete rules in EntityModeler
- From: Markus Ruggiero <email@hidden>
- Date: Wed, 27 Apr 2011 07:17:32 +0200
> Here is the model:
>
> ElectronicDocument <-->>TextblockReference<<-->Textblock. TextblockReference is more than a simple m:n join table. However I have a flattened m:n relationship between ElectronicDocument (called textblocks) and Textblock (called documents) across TextblockReference. There are other entities hanging off TextblockReference: TextblockReferemce<-->>Params<-->>Data.
On 26.04.2011, at 16:17, David Avendasora wrote:
>>>> And what should those be for the flattened relationship?
>>>
>>> I'm guessing that they should be "nullify" or "do nothing"
>>
>> Yes, only one delete rule should affect a given relationship. In fact, I always shy away from (nay, avoid completely) flattened relationships that hide objects I am actually interested in. In general, 'one path to the object' is the rule I try to follow.
>
> Absolutely! +1,000,000.
>
> EOF gets horribly confused if you have multiple paths. Never, never, never have more than one relationship in an Entity share a FK, or have a FK be a class attribute because you can set one without setting the other, or set them independently to different values, try to delete one relationship and the other still sees it as being valid but the object is long gone.
>
> Hmmm. That last one sounds familiar... :-)
That makes sense and is what caused the problems in the end. I removed the flattened relationship between ElectronicDocument and Textblock from the model and replaced it by a simple cover method in ElectronicDocument.java --> all problems gone.
Thanks to "The Davids" :-)
---markus--- _______________________________________________
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