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From Mike Kienenberger <mkien...@gmail.com>
Subject Re: Question on how to properly create parent-child nested dependent objects?
Date Wed, 20 Sep 2017 12:59:15 GMT
Yes, much easier if it's just a matter of creating objects in a
different order :-)

On Wed, Sep 20, 2017 at 8:45 AM, Nikita Timofeev
<ntimofeev@objectstyle.com> wrote:
> Other option is to create CommunicationType first and then just use it:
>
> CommunicationType type = CommunicationType.find("Email");
>
> CommunicationLog cl = oc.newObject(CommunicationLog.class);
> cl.setCommunicationDT(LocalDateTime.now());
> cl.setCommunicationType(type);
> oc.commitChanges();
>
> In this case everything will be in one context, and you can freely
> commit CommunicationType to DB.
>
> On Wed, Sep 20, 2017 at 3:37 PM, Mike Kienenberger <mkienenb@gmail.com> wrote:
>> I haven't followed the details, so I don't know if using a separate
>> object context is necessary, but all you need to do to move a data
>> object (in your case "child") to a different context is to call
>> parentContext.localObject(childDataObject) which will return
>> childDataObjectInParentContext.   Note that this requires either a
>> hollow or committed childDataObject as a modified (uncommitted) or new
>> (uncommitted) data object's changes only exist in the
>> childObjectContext.
>>
>> I may also have the syntax for localObject() wrong as I'm probably
>> using an older version of Cayenne than you are.
>>
>>
>>
>> On Wed, Sep 20, 2017 at 8:30 AM, Andrew Willerding
>> <awillerding@itsurcom.com> wrote:
>>> I guess my issue is with how independent the commits can be.  Now that I
>>> better understand this, my code example works as Nikita suggested (with the
>>> fix for my problem with the PrimaryKey table) and if I drop the commit
>>> during the creation of the child object otherwise the commit during the
>>> child creation will fail because the parent has not yet been assigned with
>>> the child object.
>>>
>>> My objective is that I want the creation of the child to be completely
>>> independent of the parent object for this situation. To do this I have to
>>> create a new ObjectContext  for the child object to make it independent of
>>> the parent's ObjectContext but when I return the newly created child object
>>> to the parent object I get the following
>>>
>>> Caused by: org.apache.cayenne.CayenneRuntimeException: [v.4.0.B1 Jun 02 2017
>>> 15:11:18] Cannot set object as destination of relationship communicationType
>>> because it is in a different ObjectContext
>>>     at
>>> org.apache.cayenne.CayenneDataObject.willConnect(CayenneDataObject.java:399)
>>>     at
>>> org.apache.cayenne.CayenneDataObject.setToOneTarget(CayenneDataObject.java:355)
>>>     at
>>> com.callistacti.clientbase.Database.auto._CommunicationLog.setCommunicationType(_CommunicationLog.java:65)
>>>     at
>>> com.callistacti.clientbase.Panel.PanelGroups.windowClose(PanelGroups.java:423)
>>>
>>> So what I then needed to do is lookup the child object with the same
>>> ObjectContext that the parent was using.
>>>
>>> Out of curiousity, is there any simpler way of doing this?
>>>
>>>
>>>
>>> On 19/09/17 09:16 AM, Aristedes Maniatis wrote:
>>>>
>>>> On 19/9/17 11:01PM, Andrew Willerding wrote:
>>>>>
>>>>> The CommunicationType object does not yet exist permanently in the
>>>>> database table so how or when does it generate the primary key for the
>>>>> object to be referenced by another object before it is committed?  I
was
>>>>> hoping to not have to worry about this as a "high-level" user of Cayenne.
>>>>
>>>>
>>>> You are right, you don't need to worry about all that. Just create one
>>>> context and save it at the end. Cayenne tracks the relationships between
>>>> objects with a temporary key internally, but you don't need to think about
>>>> that. Once Caynenne commits, everything is assigned proper primary keys and
>>>> joined.
>>>>
>>>> Ari
>>>>
>>>>
>>>
>
>
>
> --
> Best regards,
> Nikita Timofeev

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