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: Aaron Rosenzweig <email@hidden>
- Date: Sun, 13 Jan 2019 12:45:23 -0500
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 <http://www.chatnbike.com/>
e: email@hidden <mailto: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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