Ndtyjky

I have 2 tables in my database: Car and Garage

where Car and Garage are connected via foreign keys with each other:

In Car, the foreign key is carHasGarages. The whole schema looks like:

Destination: Garage

Inverse: `garageHasCar`

Delete rule: `Cascade`

Type: `To Many`

In Garage the foreign key is garageHasCar and the schema is:

Destination: Car

Inverse: `carHasGarage`

Delete rule: `Nullify`

Type: `To Many`

When I try to batch delete my garages by using the predicate:

let predicate = NSPredicate(format: "carNbr IN %@", inactiveCars)



let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Car")

request.predicate = predicate

let batchDelete = NSBatchDeleteRequest(fetchRequest: request)



do {

    try context.execute(batchDelete)

}...

where inactiveCars is the array of [Int32]

I get the next error:

error: Unhandled error from executeBatchDeleteRequest Constraint

violation: Batch delete failed due to mandatory MTM nullify inverse on Garage/garageHasCar and userInfo {

"_NSCoreDataOptimisticLockingFailureConflictsKey" =     (

    "<null>"

);

}

Can someone point to my mistake? I'm trying to solve this problem 2 days already and cannot manage it. So I thought maybe I do not see anything or miss something.
Thanks in advance for your time!

From the documentation, this request is directly called on the backing store (most probably you are using sqlite here). Since the core data framework layer isn't much involved here, it looks like your deletion is leaving your sqlite in a bad state.

My guess on bad state: all inactive cars are deleted, but the garages still hold a reference to them since their relationship wasn't handled.