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From Paul Copeland <t...@jotobjects.com>
Subject Re: Behavior of ManyToMany CascadeType.REMOVE
Date Fri, 03 Apr 2009 22:30:10 GMT
After some investigation it looks like the path of least resistance is 
to just use SQL Alter Table to add the foreign keys with delete cascade 
(I'm using forward mapping to create the database).  It is not clear to 
me how to use the @ForeignKey annotation with a ManyToMany relation 
(possibly requires using the ContainerTable annotation also?).  I also 
tried setting the MappingDefaults property ForeignKeyDeleteAction value 
but this added foreign keys on all the OneToMany and OneToOne relations 
and changed the generated SQL forward mapping in other ways.  At this 
point the annotations seem less user friendly than SQL alter table.

As far as I can tell the only JPA "standard" way to do this is to remove 
the elements one at a time from the owner side collection of the 
ManyToMany relation before removing the  owner entity.

- Paul

On 4/3/2009 11:38 AM, Paul Copeland wrote:
> Looks like I can use the OpenJPA @ForeignKey annotation 
> deleteAction=CASCADE - will give it a try.
>
> On 4/3/2009 11:18 AM, Paul Copeland wrote:
>> This is from the JPA spec - Sounds like cascade=REMOVE should not be 
>> used on ManyToMany.  However I'm recalling that some databases do 
>> provide DDL for the kind of cascade delete behavior that I want.
>>
>> 2.1.7 - "The relationship modeling annotation constrains the use of 
>> the cascade=REMOVE specification. The
>> cascade=REMOVE specification should only be applied to associations 
>> that are specified as One-
>> ToOne or OneToMany. Applications that apply cascade=REMOVE to other 
>> associations are not portable."
>>
>> On 4/3/2009 10:43 AM, Paul Copeland wrote:
>>> Will CascadeType.REMOVE on a ManyToMany mapping remove the join 
>>> table row?  Even if the Collections has not been loaded lazily? Or 
>>> do I have to iterate over the Collection and remove each element 
>>> before removing the enity? I do NOT want to remove the referenced 
>>> Entity on the other side of the ManyToMany association, just the row 
>>> in the join table.
>>>
>>> @ManyToMany (fetch=FetchType.LAZY, 
>>> cascade={CascadeType.PERSIST,CascadeType.REMOVE})
>>>
>>> - Paul
>>>
>>>
>>>
>>>
>>
>>
>>
>
>
>


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