Question

could you help me and tell me why my entity is empty ?

i’m populating my entity with my JSON, my entity’s attributes has the same name as in my JSON

this is my code to populate my entity :

  NSManagedObjectContext *cxt = [self managedObjectContext];
    NSManagedObject *newBoxes = [NSEntityDescription insertNewObjectForEntityForName:@"Boxes" inManagedObjectContext:cxt];
    NSDictionary *parsedFeed = [[newBoxes entity] attributesByName];
    for (NSString *key in parsedFeed) {
        id value = [parsedFeed objectForKey:key];
        // Don't assign NSNull, it will break assignments to NSString, etc.
        if (value && [value isKindOfClass:[NSNull class]])
            value = nil;

        @try {
            [Boxes setValue:value forKey:key];
        } @catch (NSException *exception) {
            // Exception means such attribute is not defined in the class or some other error.
        }
    }

    NSError *err;
    if (![cxt save:&err]) {
        NSLog(@"An error has occured: %@", [err localizedDescription]);
    }



NSLog(@"ENTITY  %@", newBoxes);

this is the result of my NSLOG :

2012-04-30 11:16:23.352 Wonder[9987:fb03] ENTITY  <Boxes: 0x6d87330> (entity: Boxes; id: 0x6d8b010 <x-coredata://EFDCC0BA-644D-42AC-8DE8-452F02B7C680/Boxes/p26> ; data: {
    codeArticle = nil;
    descriptionBox = nil;
    dlu = 0;
    kindBox = nil;
    nameBox = nil;
    nbActivities = 0;
    note = 0;
    priceBox = 0;
    texteMarketing = nil;
    typeBox = nil;
})

this is my JSON :

{
    "totalBox":{
        "boxes":[
        {
         "codeArticle": "WPCDE01C412L",
         "nameBox": "boxName",
         "texteMarketing": "boxTextMarketing",
         "descriptionBox" : "boxDescritpion",
         "nbActivities": 1650,
         "kindBox": "boxKind",
         "typeBox": "boxType",
         "priceBox": 20,
         "dlu": 2014,
         "note": 3
        },
        {
         "codeArticle": "BOOYAKA!!",
         "nameBox": "boxNameName",
         "texteMarketing": "boxTextMarketing",
         "descriptionBox" : "boxDescritpion",
         "nbActivities": 1650,
         "kindBox": "boxKind",
         "typeBox": "boxType",
         "priceBox": 39,
         "dlu": 2014,
         "note": 3
         }
        ]
            }
}

this is my entity :

EDIT : i give my JSON, so i should “tell” my coredata what it should read to populate my entity, right ?

dataToDisplay = [[NSMutableArray alloc] init];

//récupération du chemin vers le fichier contenant le JSON
NSString *filePath = [[NSBundle mainBundle] pathForResource:@"JSON" ofType:@"txt"];

//création d'un string avec le contenu du JSON
NSString *myJSON = [[NSString alloc] initWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:NULL];   

//Parsage du JSON à l'aide du framework importé
NSDictionary *json    = [myJSON JSONValue];

//récupération  du total des Boxes
NSDictionary *resultats    = [json objectForKey:@"totalBox"];

Answer 1

In the code above you are trying to set values on a non object.

[Boxes setValue:value forKey:key];

Should be

[newBoxes setValue:value forKey:key];

I would recommend that you take a look at http://rentzsch.github.com/mogenerator/ and this super useful article on JSON and CoreData http://www.cimgf.com/2012/01/11/handling-incoming-json-redux/

Cheers
mbogh