Re: To-one relationship with propagating primary key
Re: To-one relationship with propagating primary key
- Subject: Re: To-one relationship with propagating primary key
- From: Ricardo Parada <email@hidden>
- Date: Thu, 24 Jan 2019 13:49:36 -0500
Hi Aaron,
In my case there cannot be a B without an A and viceversa. So I am okay with
this behavior.
Regards
Ricardo
Sent from my iPhone
> On Jan 13, 2019, at 12:45 PM, Aaron Rosenzweig <email@hidden> wrote:
>
> Wait a second… thinking about this more.
>
> If you are going A -> B where A has a primary key and you have a two one
> relationship to B where you “propagate” primary key - this is a very bad
> thing!!!!!!
>
> What it means is the PK of A also points to the PK of B… it will always think
> there is a B… so it “has to” make an EO over there.
>
> You would be better off making a new integer FK on A pointing to B. Do not
> propagate primary key.
>
> AARON ROSENZWEIG / Chat 'n Bike
> e: email@hidden t: (301) 956-2319
>
>
>>> On Jan 13, 2019, at 12:42 PM, Johann Werner <email@hidden> wrote:
>>>
>>>
>>>
>>> Am 13.01.2019 um 18:37 schrieb Ricardo Parada <email@hidden>:
>>>
>>> When I create A will it have a B set in the to-one?
>>
>> I think so. It is a loooong time ago I used key propagation though.
>>
>>>
>>> Ricardo
>>>
>>>> On Jan 13, 2019, at 12:35 PM, Johann Werner <email@hidden>
>>>> wrote:
>>>>
>>>> Hi Ricardo,
>>>>
>>>> don’t fight the system ;-)
>>>>
>>>> When you have your to-one relationship A -> B with key propagation just
>>>> create an instance of A and you automatically have a B in place when you
>>>> check the relationship A.toB(). You just have to (re)use the present B
>>>> instead of creating and connecting your own B.
>>>>
>>>> jw
>>>>
>>>>
>>>>> Am 13.01.2019 um 13:07 schrieb Ricardo Parada <email@hidden>:
>>>>>
>>>>> Hi Johann,
>>>>>
>>>>> My workaround is to model the relationship as a to-many propagating the
>>>>> primary key. It’s less elegant but at least it works.
>>>>>
>>>>> Thanks
>>>>> Ricardo
>>>>>
>>>>>> On Jan 13, 2019, at 7:02 AM, Johann Werner <email@hidden>
>>>>>> wrote:
>>>>>>
>>>>>> Hi Ricardo,
>>>>>>
>>>>>> when using pk propagation I vaguely remember that EOF is automatically
>>>>>> creating an instance of the dependent entity. Thus when you create a
>>>>>> second object B and set the relationship to A the auto created object is
>>>>>> left without connection.
>>>>>>
>>>>>> jw
>>>>>>
>>>>>>> Am 13.01.2019 um 12:44 schrieb Ricardo Parada <email@hidden>:
>>>>>>>
>>>>>>> Hi all,
>>>>>>>
>>>>>>> I have an entity A with a to-one relationship to entity B.
>>>>>>>
>>>>>>> The relationship is setup in eomodeler to propagate it’s primary key
>>>>>>> from A to B.
>>>>>>>
>>>>>>> I then create A and B, insert into editing context and set the to-one
>>>>>>> relationship in A to point to B. When I save changes EOF is trying to
>>>>>>> insert TWO instances of B. The second instance of B has NULL in all its
>>>>>>> properties:
>>>>>>>
>>>>>>> INSERT INTO HOSTING_COMPANY(CUSTOMER_ID, name) VALUES (?, ?)"
>>>>>>> withBindings: 1:20462(customerID), 2:"test"(name)>
>>>>>>>
>>>>>>> INSERT INTO HOSTING_COMPANY(CUSTOMER_ID, name) VALUES (NULL, NULL)
>>>>>>>
>>>>>>>
>>>>>>> Is this a know bug? I am using a very old version of Wonder.
>>>>>>>
>>>>>>> The relationship is also set up to own the destination and Cascade on
>>>>>>> Delete.
>>>>>>>
>>>>>>> Thanks in advance for any help.
>>>>>>>
>>>>>>> Ricardo
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>>>>
>>>
>>
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