populating core data through JSON receiving null entries - ios

Question

Trying to populate core data structure using JSON,
The code is listed below?
NSManagedObjectContext *context = managedObjectContext();
// Save the managed object context
NSError *error = nil;
if (![context save:&error]) {
NSLog(#"Error while saving %#", ([error localizedDescription] != nil) ? [error localizedDescription] : #"Unknown Error");
exit(1);
}
NSError* err = nil;
NSString* dataPath = [[NSBundle mainBundle] pathForResource:#"Exercises" ofType:#"json"];
NSArray* Exercises = [NSJSONSerialization JSONObjectWithData:[NSData dataWithContentsOfFile:dataPath]
options:kNilOptions
error:&err];
NSLog(#"Imported Exercises: %#", Exercises);
NSManagedObject *object = [NSEntityDescription insertNewObjectForEntityForName:#"Exercise" inManagedObjectContext:context];
NSString *theJSONString = #"{\"key\":\"value\"}";
NSError *theError = NULL;
NSDictionary *jsonDict = [NSDictionary dictionaryWithJSONString:theJSONString error:&theError];
Exercise *exercise = [NSEntityDescription insertNewObjectForEntityForName:#"Exercise"
inManagedObjectContext:context];
[Exercises enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSDictionary *attributes = [[object entity] attributesByName];
for (NSString *attribute in attributes) {
id value = [jsonDict objectForKey:attribute];
if (value == nil) {
continue;
}
[exercise setValue:value forKey:attribute];
}
NSError *error;
if (![context save:&error]) {
NSLog(#"Whoops, couldn't save: %#", [error localizedDescription]);
}
}];
The code compiles and after analysing the sqlite database created, all attributes are filled with null values.
NSString* secondDataPath = [[NSBundle mainBundle] pathForResource:#"Weights" ofType:#"json"];
NSArray* weightsFromJSON = [NSJSONSerialization JSONObjectWithData:[NSData dataWithContentsOfFile:secondDataPath]
options:kNilOptions
error:&err];
NSLog(#"Imported weightsFromJSON: %#", weightsFromJSON);
[weightsFromJSON enumerateObjectsUsingBlock:^(NSDictionary *weightDictionary, NSUInteger idx, BOOL *stop) {
Weight *weight = [NSEntityDescription insertNewObjectForEntityForName:#"Weight"
inManagedObjectContext:context];
NSDictionary *attributes = [[weight entity] attributesByName];
for (NSString *attribute in [attributes allKeys]) {
id value = [weightDictionary objectForKey:attribute];
if (value == nil) {
continue;
}
[weight setValue:value forKey:attribute];
}
NSError *error;
if (![context save:&error]) {
NSLog(#"Whoops, couldn't save: %#", [error localizedDescription]);
}
}];
Edited the code above for the second entity, but fails stating data parameter is hill

Answer 1

You're enumerating every object loaded from the JSON data on disk that you put into Exercises (as an aside, don't capitalize the names of local variables) but then you are not using those objects as the data source, instead you're using jsonDict which is hard-coded from a string and has only one key/value pair. Try changing the line
id value = [jsonDict objectForKey:attribute];
To instead say:
id value = [(NSDictionary *)obj objectForKey:attribute];
That should actually apply the data you loaded. However, there are other problems in your code - you only insert a single entity, not one for each element in Exercises, as well as inserting an extraneous one that you assign to object. Here's some code that I think may do what you're trying to do:
NSError* err = nil;
NSString* dataPath = [[NSBundle mainBundle] pathForResource:#"exercisesFromJSON" ofType:#"json"];
NSArray* exercisesFromJSON = [NSJSONSerialization JSONObjectWithData:[NSData dataWithContentsOfFile:dataPath]
options:kNilOptions
error:&err];
NSLog(#"Imported exercisesFromJSON: %#", exercisesFromJSON);
[exercisesFromJSON enumerateObjectsUsingBlock:^(NSDictionary exerciseDictionary, NSUInteger idx, BOOL *stop) {
Exercise *exercise = [NSEntityDescription insertNewObjectForEntityForName:#"Exercise"
inManagedObjectContext:context];
NSDictionary *attributes = [[exercise entity] attributesByName];
for (NSString *attribute in [attributes allKeys]) {
id value = [exerciseDictionary objectForKey:attribute];
if (value == nil) {
continue;
}
[exercise setValue:value forKey:attribute];
}
NSError *error;
if (![context save:&error]) {
NSLog(#"Whoops, couldn't save: %#", [error localizedDescription]);
}
}];