CODEWITHSUNDEEP
iosswiftcore-data
Qian Wang
Qian Wang

Reputation: 854

IOS - How to clean database with NSBatchDeleteRequest

With swift 2.1 and CoreData, I want to delete all data of my database.

with following way, it works well

let context = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
let request = NSFetchRequest(entityName: "UserCourse")
let arr = try! context.executeFetchRequest(request)
for item in arr{
    context.deleteObject(item as! NSManagedObject)
    try! context.save()
}

but i heard that there is a better way to do that with NSBatchDeleteRequest

here is the code

let context = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
let model = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectModel
let delete = NSBatchDeleteRequest(fetchRequest: NSFetchRequest(entityName: "Data"))
let coordinator = NSPersistentStoreCoordinator(managedObjectModel: model)
try! coordinator.executeRequest(delete, withContext: context)

but it raise an error said 

2015-12-10 01:36:21.195 test[1090:40088] CoreData: error: Illegal attempt to save to a file that was never opened. "This NSPersistentStoreCoordinator has no persistent stores (unknown).  It cannot perform a save operation.". No last error recorded.
2015-12-10 01:36:21.202 test[1090:40088] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'This NSPersistentStoreCoordinator has no persistent stores (unknown).  It cannot perform a save operation.'

I wonder there must be something wrong with the model or coordinator, but I can't figure out how to get a correct coordinator instance, someone can help me?

Upvotes: 1

Views: 707

Answers (1)

pbasdf
pbasdf

Reputation: 21536

This line:

let coordinator = NSPersistentStoreCoordinator(managedObjectModel: model)

creates a new persistentStoreCoordinator, associated with your model, but does not link it to a persistentStore. Hence the error message.

I suspect actually need to use the existing persistentStoreCoordinator associated with your context:

let coordinator = context.persistentStoreCoordinator

Upvotes: 1

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