Hi Andrew,
I'm jumping in late here, but I did something very similar to what you are
trying to do with CommunicationType.find(). I create (auto-populate) a
reference table record based upon some enum values if missing, or just
return the reference table record if I find it. I do this in a completely
separate (not a child) DataContext and copy the result into the main
destination context passed into the method.
This is from 3.1, so might vary a bit on the last line if you are on 4.x
(I'm using a deprecated method there and haven't updated yet):
public static ContractDesignation fetch(ObjectContext
destinationContext,
ContractMethodType
contractMethod,
ContractType contractType,
FundingVehicleType
fundingVehicle)
{
ContractDesignation contractDesignation = null;
DataContext dataContext =
CayenneUtils.createDataContext();
Expression exp1 =
ExpressionFactory.matchExp(CONTRACT_METHOD_PROPERTY, contractMethod);
Expression exp2 =
ExpressionFactory.matchExp(CONTRACT_TYPE_PROPERTY, contractType);
Expression exp3 =
ExpressionFactory.matchExp(FUNDING_VEHICLE_PROPERTY, fundingVehicle);
Expression exp =
exp1.andExp(exp2).andExp(exp3);
SelectQuery query = new
SelectQuery(ContractDesignation.class, exp);
@SuppressWarnings("unchecked")
List<ContractDesignation> contractDesignations =
dataContext.performQuery(query);
// If no contract designation is found, create a new one, else use
the
// one that was found (throwing an exception if too many are found).
if (contractDesignations.isEmpty())
{
contractDesignation =
dataContext.newObject(ContractDesignation.class);
contractDesignation.setContractMethod(contractMethod);
contractDesignation.setContractType(contractType);
contractDesignation.setFundingVehicle(fundingVehicle);
dataContext.commitChanges();
}
else if (contractDesignations.size() == 1)
{
contractDesignation = contractDesignations.get(0);
}
else
{
// There can be only one!
throw new TooManyResultsException("There can be at most one
match for ContractDesignation contractMethod='" + contractMethod +
"' / contractType='" +
contractType +
"' / fundingVehicle='" +
fundingVehicle + "'");
}
// Pull the fetched ContractDesignation into the destination
ObjectContext.
return (ContractDesignation)
DataObjectUtils.objectForPK(destinationContext,
contractDesignation.getObjectId());
}
On Wed, Sep 20, 2017 at 9:16 AM, Andrew Willerding <[email protected]
> wrote:
> I thought of this too but I'm trying to create the child object
> dynamically without having any impact on the parent object or making the
> coder of the parent object worry about creating child objects first.
>
>
>
> On 20/09/17 08:45 AM, Nikita Timofeev 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 <[email protected]>
>> 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
>>> <[email protected]> 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(CayenneData
>>>> Object.java:399)
>>>> at
>>>> org.apache.cayenne.CayenneDataObject.setToOneTarget(CayenneD
>>>> ataObject.java:355)
>>>> at
>>>> com.callistacti.clientbase.Database.auto._CommunicationLog.s
>>>> etCommunicationType(_CommunicationLog.java:65)
>>>> at
>>>> com.callistacti.clientbase.Panel.PanelGroups.windowClose(Pan
>>>> elGroups.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
>>>>>
>>>>>
>>>>>
>>
>>
>
