NSBatchUpdateRequest for one-to-many relationship

Question

I am trying to use NSBatchUpdateRequest to update a one-to-many relationship.

My entity, Presentation, has multiple Slide, which is another entity, and they have an inverse relationship.

When I try to update slides, I get this error:

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Invalid relationship ((), name slides, isOptional 1, isTransient 0, entity Presentation, renamingIdentifier slides, validation predicates ( ), warnings ( ), versionHashModifier (null) userInfo { }, destination entity Slide, inverseRelationship presentation, minCount 0, maxCount 0, isOrdered 0, deleteRule 1) passed to propertiesToUpdate:'

I've tried to search for this error, but couldn't find any results.

My code:

let entity = NSEntityDescription.entityForName("Presentation", inManagedObjectContext: managedObjectContext)
let batchRequest = NSBatchUpdateRequest(entity: entity!)
batchRequest.resultType = .UpdatedObjectIDsResultType
batchRequest.propertiesToUpdate = ["date_updated": formattedDateUpdated, "slides": presentationSlides]

do {
      let batchUpdateResult = try managedObjectContext.executeRequest(batchRequest) as! NSBatchUpdateResult
      let objectIds = batchUpdateResult.result as! [NSManagedObjectID]

      for objectId in objectIds {
          let managedObject = managedObjectContext.objectWithID(objectId)

          managedObjectContext.refreshObject(managedObject, mergeChanges: false)
      }
 } catch {
          let updateError = error as NSError
          print(updateError)
 }

date_updated updated just fine, so I don't think this is the correct way of updating a relationship.

If anyone needs more code, please let me know. Thanks for any help.

Answer 1

I think you need to separate this batch request for two, one is for Presentation class instances:

let entity = NSEntityDescription.entityForName("Presentation", inManagedObjectContext: managedObjectContext)
let batchRequest = NSBatchUpdateRequest(entity: entity!)
batchRequest.resultType = .UpdatedObjectIDsResultType
batchRequest.propertiesToUpdate = ["date_updated": formattedDateUpdated]

The second is for Slides class instances, that you can filter using predicate:

let entity = NSEntityDescription.entityForName("Slide", inManagedObjectContext: managedObjectContext)
let batchRequest = NSBatchUpdateRequest(entity: entity!)
batchRequest.resultType = .UpdatedObjectIDsResultType
batchRequest.predicate = NSPredicate(format: "presentation = %@ \(somePresentation)");
batchRequest.propertiesToUpdate = ["some_property": newValue]