How to get batch-inserts with back references to work?

Question

Here's my Android problem that I've spend hours on already:

I am inserting objects in table CARS, followed by objects in table DRIVERS. I need DRIVERS's foreign-key to be set correctly to reference the just inserted row in CARS. Also, if row in DRIVERS cannot be saved, CARS should not be saved, as well. (transactiomn-semantics)

I am using the ContentProvider-approach.

I understand I should use a batch insert and withValueBackReference for this task.

Example code:

// (populate carData obejct..)

ArrayList<ContentProviderOperation> opList = new
                ArrayList<ContentProviderOperation>();

ContentValues carv = new ContentValues();
carv.put(Car.CAR_MAKE, carData.make);
carv.put(Car.CAR_MODEL, carData.model);
carv.put(BaseColumns._ID, 0); // this HAS to be here or withBackValues doesn't work

opList.add(ContentProviderOperation.newInsert(Car.CONTENT_URI).withValues(carv).build());

ContentValues driverv = new ContentValues();
driverv.put(Driver.DRIVER_NAME, carData.driverName);
driverv.put(Driver.DRIVER_CAR_FK, 0); // THIS should set the ID of the car above!

opList.add(ContentProviderOperation. newInsert(Driver.CONTENT_URI).withValues(driverv)
          .withValueBackReference(Driver.DRIVER_CAR_FK, 0).build());

//... applyBatch etc.

If I leave out carv.put(BaseColumns._ID, 0) it doesn't work. If I leave it in, I have to set the value AUTO INCREMENT would have assigned. (Driver._ID is set to be the primary key.)

So my question is,

how to to have the CARS row set its own _ID, and reference this id in the second insert of the batch, when I insert the DRIVER?

Help is very appreciated, the documentation isn't very clear..

Answer 1

This is probably too late to help, but you seem to have the right idea. From your example your db naming scheme is a little confusing. You should not need carv.put(BaseColumns._ID, 0); because the database should be creating this value for you. You also don't need to put driverv.put(Driver.DRIVER_CAR_FK, 0); though it won't hurt - according to the docs value back references take precedence. If there are still issues then it is probably because of the way the foreign keys in your database are set up.

ArrayList<ContentProviderOperation> opList = new
        ArrayList<ContentProviderOperation>();

ContentValues carv = new ContentValues();
carv.put(Car.CAR_MAKE, carData.make);
carv.put(Car.CAR_MODEL, carData.model);
opList.add(ContentProviderOperation.newInsert(Car.CONTENT_URI).withValues(carv).build());

ContentValues driverv = new ContentValues();
driverv.put(Driver.DRIVER_NAME, carData.driverName);

opList.add(ContentProviderOperation.newInsert(Driver.CONTENT_URI)
          .withValues(driverv)
          .withValueBackReference(Driver.DRIVER_CAR_FK, 0).build());