I'm making an iOS app with different types of quizzes, with all the questions and answer choices stored in CoreData.
I created two entities, one called QuestionData that has attributes such as 'question' 'answer1' (meaning, answer choice 1), 'answer2' etc, and then another entity called Quiz, with attributes like 'name' and 'quizId' and I created a to-many relationship on Quiz called 'dataData' that will refer to all the questions/answers etc.
When I created some test data (to experiment with the relationships), I first created the questionData, then set the name and id for the Quiz, and then I tried to set the data in the relationship like this,
[quizInfo setValue:questionData forKey:#"quizData"];
Which was supposed to store/set all the questions/answers in the quizData key of the Quiz entity. However, I got this unacceptable type error, telling me that it 'desired' an NSSet, but i instead gave it a type of QuestionData.
'NSInvalidArgumentException', reason: 'Unacceptable type of value for to-many relationship: property = "quizData"; desired type = NSSet; given type = QuestionData; value = <QuestionData: 0x89447a0> (entity: QuestionData; id: 0x8919900 <x-coredata:///QuestionData/t6B583F60-5794-47FA-8A51-
I understand the concept of a 'set' however, I'm not sure how I can make questionData a set when it comes time to do this
[quizInfo setValue:questionData forKey:#"quizData"];
Full code:
NSManagedObjectContext *context = [self managedObjectContext];
QuestionData *questionData = [NSEntityDescription
insertNewObjectForEntityForName:#"Questiondata"
inManagedObjectContext:context];
[questionData setValue:#"do you like big basketballs" forKey:#"question"];
[questionData setValue:#"yes" forKey:#"answer1"];
[questionData setValue:#"no" forKey:#"answer2"];
[questionData setValue:#"maybe" forKey:#"answer3"];
[questionData setValue:#"maybe" forKey:#"correctAnswer"];
Quiz *quizInfo = [NSEntityDescription
insertNewObjectForEntityForName:#"Quiz"
inManagedObjectContext:context];
[quizInfo setValue:#"1" forKey:#"quizId"];
[quizInfo setValue:#"sportsquiz" forKey:#"name"];
[quizInfo setValue:questionData forKey:#"quizData"];
You need to wrap your questionData inside a set. Since you only have one question at this time you can use
[quizInfo setValue:[NSSet setWithObject:questionData] forKey:#"quizData"];
When you have more than one question you can either use:
[quizInfo setValue:[NSSet setWithObjects:question1Data,question2Data,question3Data,nil] forKey:#"quizData"];
Or you could put your questions into an NSMutableArray and use
[quizInfo setValue:[NSSet setWithArray:questionArray] forKey:#"quizData"];
Related
1) I have NSFetchedResultsController with some Collection Views and I use defaultManagedObjectContext to keep context for it, which one is NSMainQueueConcurrencyType and it set, as a child for NSPrivateQueueConcurrencyType.
2) I have NSArray of NSStrings taken from CoreData in same defaultManagedObjectContext. This string I use like predicate, like filters option in window below. Filter works as it should.
3) And I have method to change Collection View element (for example, set LIKE) in another backgroundManagedObjectContext (NSPrivateQueueConcurrencyType), it set as child for defaultManagedObjectContext. Likes button works as it should.
But when I trying to use together (Predicate and Set like method), CoreData down with error:
The left hand side for an ALL or ANY operator must be either an
NSArray or an NSSet.
Should I use another context to keep predicate?
As child for defaultManagedObjectContext?
Predicate like this:
[NSEntityDescription entityForName:#"NMObject"
inManagedObjectContext:self.managedObjectContext];
self.selectedTypes = [[NSArray alloc] initWithObjects:#"музей", nil];
_predicate = [NSPredicate predicateWithFormat:#"ANY types.typeObjValue IN %#", self.selectedTypes];
So, NMObject has relationship with NMTypeObj as NMObject types <<-----> NMTypeObj objects
Thank you everybody!
The problem was with predicate format. if relationship is NMObject types <<--Many to One--> NMTypeObj objects is possibly to use ANY. Correct relationship for ANY is, for example, NMObject types <--One to Many-->> NMTypeObj objects
So, in my case, I change predicate to:
_predicate = [NSPredicate predicateWithFormat:#"types.typeObjValue IN %#", self.selectedTypes];
I know that several issues possibly duplicated being, however, no pointed solution solved my problem, so I decided to post my specific case.
I'm working with CoreData in my application, and some objects are instantiated without being effectively saved on the ground, my startup code in these cases is as follows:
-(id)initEntity:(NSManagedObjectContext*)context{
AppDelegate appDelegate * = [[UIApplication sharedApplication] delegate];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Endereco" inManagedObjectContext: appDelegate.managedObjectContext];
self = (Endereco*)[[Endereco alloc] initWithEntity:entity insertIntoManagedObjectContext:nil];
return self;
}
However, an attribute of this object is the municipality that is already saved on the base, and is selected by a ActionSheet:
if (actionSheet == actionSheetMunicipios) {
Municipio *municipio = [municipios objectAtIndex:buttonIndex-1];
endereco.municipio = municipio;
[textMunicipio setText:endereco.municipio.nome];
}
in line
endereco.municipio = municipio;
I get the following error:
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Illegal attempt to establish a
relationship' municipio 'between objects in different contexts.
The error is clear, I am trying to establish a relationship of objects with different contexts, but in my case, in which the Parent object is not saved on the base, and that the child object is already there, how could I solve?
Your comments seem to indicate you know the answer. Add endereco to the context (use insertIntoManagedObjectContext: context rather than insertIntoManagedObjectContext: nil). It's not a matter of being saved; you need to make sure that the two objects are in the same context. There is no way around that. You cannot create cross-context relationships in properties (you can in fetched properties, but it's complicated and this doesn't seem like a case where you want it).
I managed to solve the problem by adding the Endereco in the managedContext of the Municipio:
if (actionSheet == actionSheetMunicipios) {
Municipio *municipio = [municipios objectAtIndex:buttonIndex-1];
[municipio.managedObjectContext insertObject:endereco];
[endereco setMunicipio:municipio];
[textMunicipio setText:endereco.municipio.nome];
}
I do not know if it's the best solution, but it worked perfectly in this case.
I'm building an app that requires a core data relationship as such:
entityA <<---> entityB (e.g. any given entityA can hold many entityB objects)
I have two tableviews with entityA list items in which I want to be able to store entityB objects in any given entityA object.
I'm new to using relationships with core data (and fairly new to swift) and would like to learn how to make this work. Does anyone have any swift tutorials in mind that would be good for me to take a look at or any other resources that may help me learn?
Sorry if my question doesn't make much sense, ask me to clarify if you need.
Thanks!
UPDATE:
Here's a bit more specificity on what I'm wanting to learn.
Lets say I have the entity "Person" (attributes may include name, age, etc.) and a tableview in which my app users can add a person to. (this I have established and know how to do appropriately) But, now I want to add the entity "Meal" (attributes may include food items), and Meal is a tableview of its own that I can access by choosing the person that I want to add a meal to. Each person can have more than one meal, but there can only be one person per meal.
The question is: what would my core data model, fetchRequests, etc look like in order to accomplish this?
Hope that is clear enough! :)
Thanks
Here's a code snippet of my function for creating a meal:
func createMeal() {
let entityDescription = NSEntityDescription.entityForName("Meal", inManagedObjectContext: managedObjectContext!)
let meal = Meal(entity: entityDescription!, insertIntoManagedObjectContext: managedObjectContext)
meal.mealName = mealNameTxt.text
meal.mealItem1 = mealItem1Txt.text
managedObjectContext?.save(nil)
}
Well, it's pretty simple. Let's have an example, you have a branch and the branch has lots of specifications. Firstly you need to go to your xcdatamodel and create your data entities
Then you open you editor (table style) and make the relation in your branch entity
After that you will need to set up the relation typo in your branchSpecs too
And that's it! You have just created a relationship between your CoreData entities. All you need to do is to generated the subclassed objects
And now you're all set. You will find a NSSet * object in your branch class that holds the data related specs of that branch. Also your will find a method called addSpecsObject that you can use to store the specs object.
A code sample in my case:
Branch * branch = [NSEntityDescription insertNewObjectForEntityForName:#"Branch"
inManagedObjectContext:managedObjectContext];
branch.name = obj.name;
branch.lattitude = obj.latitude;
branch.longitude = obj.longitude;
branch.dispalyedDescription = obj.dispalyedDescription;
for (FLBranchesSpecs * spec in obj.branchSpecs) {
BranchSpecs * branchSpec = [NSEntityDescription insertNewObjectForEntityForName:#"BranchSpecs"
inManagedObjectContext:managedObjectContext];
branchSpec.type = #(spec.type);
branchSpec.key = spec.key;
branchSpec.value = spec.value;
[branch addSpecsObject:branchSpec];
}
NSError *error;
if (![managedObjectContext save:&error])
NSLog(#"Whoops, couldn't save: %#", [error localizedDescription]);
A something similar than what you want
let person: AnyObject = NSEntityDescription.insertNewObjectForEntityForName("Person", inManagedObjectContext: self.managedObjectContext!)
//do you code assignment here
for meal in listOfMeals{
person.addMealObject(meal)
}
var error: NSError?
self.managedObjectContext?.save(&error)
I've got a really frustrating problem that I'd like help understanding and perhaps even fixing.
I'm learning Core Data by building a rather simple app.
My model is as follows:
User
Attributes
name
gender
dob
Relationships
hasCompletedItem - "A user can complete many list items, A list item can be completed by many users"
isInAgeGroup - "A user is in one AgeGroup, an AgeGroup can contain multiple users"
AgeGroup
Attributes
title
Relationships
hasItems - "An AgeGroup has many ListItems associated with it, a ListItem can only be associated with one AgeGroup"
hasUsers - "An AgeGroup has many users associated with it, A user can only be in 1 AgeGroup"
ListItem
Attributes
itemText
Relationships
completedByUser - "A list item can be completed by many users, a user can complete many list items".
forAgeGroup - "A list item is assigned to a single AgeGroup, an AgeGroup can have multiple listItems"
My program is set up as follows:
The AppDelegate handles creating the CoreData stack.
didFinishLaunchingWithOptions accesses MenuViewController and passes through the managedObjectContext for it to use:
id navigationController = [[self window] rootViewController];
id controller = [navigationController topViewController];
[controller setManagedObjectContext:[self managedObjectContext]];
The MenuViewController displays. It is a UIViewController with a few buttons which each segue to other view controllers.
When the 'Start' button is pressed on the MenuViewController, the existing managedObjectContext is passed on in the prepareForSegue method:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:#"selectprofile"]) {
[[segue destinationViewController] setManagedObjectContext:[self managedObjectContext]];
}
}
The SelectProfileTableViewController is then shown. It lists each User in a table. It has a button to allow adding new Users. The data for the tableview is provided by an NSFetchedResultsController which basically just fetches all records from the User entity.
Tapping the "Add" button will load the AddProfileViewController but not before passing on the managedObjectContext:
AddProfileViewController *viewController = (AddProfileViewController *)[[segue destinationViewController] topViewController];
[viewController setManagedObjectContext:self.managedObjectContext];
The AddProfileViewController is just a UIViewController. It has textFields for the name, D.O.B, etc.
It has a method addProfileDone that gets called when the user taps the "Done" button. In this method a new User managedObject is created and its attributes are set:
User *newMO = [NSEntityDescription insertNewObjectForEntityForName:#"User" inManagedObjectContext:_managedObjectContext];
newMO.name = self.nameTextField.text;
newMO.dob = _dob;
// etc
Next, it also attempts to set the relationship between this new User entity and it's corresponding AgeGroup entity.
NSFetchRequest *ageGroupRecordRequest = [NSFetchRequest fetchRequestWithEntityName:#"AgeGroup"];
NSSortDescriptor *sort = [[NSSortDescriptor alloc] initWithKey:#"title"
ascending:YES];
[ageGroupRecordRequest setSortDescriptors:[NSArray arrayWithObject:sort]];
// Make a predicate to find the correct AgeGroup based on what was calculated
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"(title == %#)", ageGroup];
[ageGroupRecordRequest setPredicate:predicate];
// Run the fetch request, should only ever get 1 result back.
NSError *fetchError;
// Result will be an array with a single AgeGroup entity
NSArray *fetchedObjects = [_managedObjectContext executeFetchRequest:ageGroupRecordRequest error:&fetchError];
// Set up the relationship using the fetched entity
// Crashes when saving if below line is uncommented
newMO.isInAgeGroup = fetchedObjects[0];
As noted in the code, when the line is uncommented and the managedObjectContext goes to save, i get the following error:
CoreData: error: failed to resolve optimistic locking failure: optimistic locking failure with (null)
CoreData: error: failed to resolve optimistic locking failure. Old save request was: { inserts ((
"0x942dd40 "
)), updates ((
"0x8e4ed60 "
)), deletes () locks () }
2014-04-12 20:00:09.482 ChekList[6076:60b] CoreData: error: failed to resolve optimistic locking failure. Next attempt will be: { inserts ((
"0x942dd40 "
)), updates ((
"0x8e4ed60 "
)), deletes () locks () }
sql: BEGIN EXCLUSIVE
annotation: getting max pk for entityID = 3
annotation: updating max pk for entityID = 3 with old = 4017 and new = 4018
sql: COMMIT
sql: BEGIN EXCLUSIVE
sql: UPDATE ZAGEGROUP SET Z_OPT = ? WHERE Z_PK = ? AND (Z_OPT = ? OR Z_OPT IS NULL)
details: SQLite bind[0] = (int64)1
details: SQLite bind[1] = (int64)6
details: SQLite bind[2] = nil
sql: ROLLBACK
sql: SELECT Z_PK,Z_OPT FROM ZAGEGROUP WHERE Z_PK IN (6) ORDER BY Z_PK
annotation: sql execution time: 0.0006s
My understanding is that basically something else has modified the context, and during the save CoreData has noticed this and stopped. I've read about changing the MergePolicy on the ManagedObjectContext but I don't really want to do this without knowing why I have to.
It's interesting to note that if I comment out the line that attempts to set the relationship it works fine. (except of course the relationship isn't set)
As far as I can see I am passing the managedObjectContext correctly to each view controller. I have also made sure that there are not multiple contexts accessing the same persistent store.
Is it likely to be the FetchedResultsController in the previous View Controller that is modifying the context for some reason?
Is anyone able to offer some information and perhaps a possible solution? I'd rather not have to change the merge policy. I can't see why I should have to considering its a rather simple example. I've been pulling my hair out most of the day on this.
I can't help but think it's most likely something simple I'm missing.
Thanks,
Brett.
I was able to figure out the solution.
Turns out that my whole problem was caused by my preloaded database.
I have a preloaded database that I copy over in the AppDelegate. Turns out that something was wrong with it.
I found this out by commenting out the lines that copied the database over and instead manually added the preloaded data in the AppDelegate. I was able to add data and also set the relationships.
From there I created a new preloaded database and it works fine.
I also found a great Apple developer example -
https://developer.apple.com/library/ios/samplecode/iPhoneCoreDataRecipes/Introduction/Intro.html
Which also showed me an alternative way of adding new entities. In this case they create the actual entity in the prepareForSegue method and pass just the entity not the entire context.
I changed my app to use that method as well (before I figured out that the database was the issue) but it still crashed. I've decided to keep it that way though as it seems more elegant.
I had this same issue but the suggested solution wasn't working for me. What worked was to create the context using concurrency type: NSMainQueueConcurrencyType even though I don't need it and I'm not using concurrency at all but somehow copying the preloaded database created the optimistic locking failure. Then wrap the save call in a the context's performBlockAndWait:
To create the context:
[[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
To save changes:
__block NSError *error = nil;
__block BOOL savedOK = NO;
[managedObjectContext performBlockAndWait:^{
savedOK = [managedObjectContext save:&error];
}];
This is even documented in iOS API, look for Concurrency inside NSManagedObjectContext class.
There is a core data model with two entities i my iOS application.
Entity: Unit / Attributes: unit_name - NSString
->> Relationship to Exercise (one to many)
Entity: Exercise / Attributes: exercise_name - NSString .
So one unit can have many exercises.
In my table view controller are all available exercises listed.
(So in the first time, i make a fetch request for the Exercise entity and the managedObjectContext points to this entity.
If i want to save a "NEW" unit with exercises the save function doesn't work.
There is no error at all, but the unit table is still empty.
Here is the code for the save function:
Units *newUnit = [NSEntityDescription insertNewObjectForEntityForName:#"Units" inManagedObjectContext:[self.coreDataHelper managedObjectContext]];
newUnit.unit_name = unitTextField.text;//Attribute
newUnit.exercises = exerciseSet;//Relationship (NSSet)
NSError *error = nil;
if (![[self.coreDataHelper managedObjectContext]save:&error]) {
NSLog(#"There was an error! %#", error);
}
else {
NSLog(#"Success!");
}
It seems like the managedObjectContext still points to the Exercise entity. (Because it was initialized the first time with this entity) the coreDataHelper has the NSPersistentStoreCoordinator, the NSManagedObjectContext, the NSManagedObjectModel and some methods to read write and delete.
Thanks for help!
Just to verify that everything is connected the way it ought to be, add
NSAssert(self.coreDataHelper, #"null coreDataHelper");
NSAssert(self.coreDataHelper.managedObjectContext, #"null MOC");
NSLog(#"available entities: %#",
self.coreDataHelper.managedObjectContext.persistentStoreCoordinator.managedObjectModel.entitiesByName);
You ought to see "Units" as one of your entities, if you've set everything up correctly.
And then after your insertion of newUnit, verify that it worked:
NSAssert(newUnit, #"newUnit didn't get inserted");
This smells like a logic error to me, by the way: you're creating a new Units instance every time you save? Are you sure you don't want to use a find-or-create pattern instead?