CODEWITHSUNDEEP
ioscore-datarestkitrestkit-0.20
Tyler Cloutier
Tyler Cloutier

Reputation: 2050

Exception when creating an RKConnectionDescription with initWithRelationship:attributes:

I am having an interesting problem with RestKit. I want to be able to map my objects by their uniqueIDs in CoreData. It looks like RKConnectionDescription should allow me to do just that. I want to set up a connection between a RegisteredUser and a BasicModel object. The thing is that when I create the connection I receive an NSInternalInconsistencyException because RestKit says, Cannot connect relationship: invalid attributes given for source entity 'RegisteredUser'

Below is the code I have to create the mapping for the user.

RKEntityMapping *userEntityMapping = [RKEntityMapping mappingForEntityForName:@"RegisteredUser" inManagedObjectStore:[RKManagedObjectStore defaultStore]];
[userEntityMapping addAttributeMappingsFromArray:@[@"uniqueID",
                                                   @"createdAt",
                                                   @"updatedAt",
                                                   @"firstName",
                                                   @"middleName",
                                                   @"lastName",
                                                   @"email",
                                                   @"gender",
                                                   @"dateOfBirth",
                                                   @"profileImageUpdatedAt"]];
NSEntityDescription *userEntity = [NSEntityDescription entityForName:@"RegisteredUser" inManagedObjectContext:[RKManagedObjectStore defaultStore].mainQueueManagedObjectContext];
NSRelationshipDescription *basicModelRelationship = [userEntity relationshipsByName][@"basicModel"];
RKConnectionDescription *connection = [[RKConnectionDescription alloc] initWithRelationship:basicModelRelationship attributes:@{@"basicModel": @"uniqueID"}];
[userEntityMapping addConnection:connection];

In core data a RegisteredUser has a one to one relationship with a BasicModel entity called basicModel. Additionally the BasicModel entity has a uniqueID attribute.

As far as I can figure, I am creating the RKConnectionDescription correctly according to the example here. The problem is that when I call initWithRelationship:attributes:, it asserts that there is a basicModel attribute on the RegisteredUser entity, which of course the isn't. There is only a basicModel relationship and so I get the crash I described above.

Why does RestKit even check that the RegisteredUser has an attribute basicModel if it expects me to be creating a connection for a relationship? Am I missing something here?

Upvotes: 0

Views: 238

Answers (1)

Wain
Wain

Reputation: 119031

Using a RKConnectionDescription is correct, but how you're using it is wrong. In this line:

initWithRelationship:basicModelRelationship attributes:@{@"basicModel": @"uniqueID"}];

you are telling RestKit about the relationship, but that it should use an attribute named basicModel in the RegisteredUser entity to find the BasicModel to connect to, matching the value of basicModel in the RegisteredUser with uniqueID in the BasicModel.

So, it is basicModel that needs to change. You need to add an attribute, like basicModelId to the RegisteredUser entity. It can be transient. Add it to the RegisteredUser mapping and use basicModelId in the RKConnectionDescription.

Upvotes: 1

Related Questions