Question

In my app i’m using core data as a db manager. This is more or less my database scheme:

Table: Device(
id: String,
name: String,
specsId: String
);
Table: Specs(
specsId: String,
/**/
);

The two tables are not joined in any way.

What i want to do is when i query a device from the Device table then automatically query the specs to it from the Specs table based on the matching specsId.

What is the proper way to do so?

Thanks,

Z

Answer 1

The proper way to do this is to drop the “specsId” field from the Device table and to create a relationship to the Specs table called something like “spec”.

This way, once you have the Device object you can just use…

myDeviceObject.spec.<property of spec>;

to access the spec.

Without having the join you would have to create an NSFetchRequest to get the Device object that you want and then to create a new NSFetchRequest to get the Spec object for that Device.

The second NSFetchRequest will have a predicate something like…

@"specsId = %@", device.specsId