openerp-expert-framework team mailing list archive

[Cloves Almeida <cjalmeida@xxxxxxxxx>]

Many-to-many associations as so rare that we should keep them simple. 
Hibernate/JPA implement them as mapping between sets (no duplicates) I 
believe OERP should follow this behavior.

IMO, it's a bug.

Dukai Gábor escreveu:
> Hi!
> There is a problem with the data integrity of relations stored in many2many 
> fields. Currently code in OpenERP assumes that many2many relations doesn't have 
> duplicates (object1 is not connected to object2 more than one time). However, 
> those tables that store many2many relations allow the same object_id pairs get 
> duplicated, and when that happens, code that uses the many2many field starts to 
> misbehave.
>
> Examples:
> -Although the client theoretically doesn't allow this, a user managed to add 
> the same sales tax to a product two times. The client doesn't display the same 
> tax twice but the tax computing method in account.tax computes a double 
> amount. You can imagine, with lots of products, how difficult it is to spot this 
> kind of problems.
> -Adding relations one-at-a-time to a many2many field with [(4, object_id)] 
> doesn't check if that relation has already been added or not.
>
> IMHO if the ORM set unique(object1_id,object2_id) for the relation tables 
> would ensure that we are free from this kind of errors. I wonder why this 
> check hasn't been added to OpenERP so far.
>
> What is the opinion of the experts on this matter?
>
>
> Regards,
> Gábor Dukai
>
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