How to specify child objects type in an NSArray with Mantle

Question

If I have a dictionary like

{
  name: "Bob",
  cars: [
    { make: "ford", year: "1972" },
    { make: "mazda", year: "2000" }
  ],
}

and two models like:

@interface CarModel : MTLModel

@property (nonatomic, strong) NSString *make;
@property (nonatomic, strong) NSString *year;

@end

@interface PersonModel : MTLModel

@property (nonatomic, strong) NSString *name;
@property (nonatomic, strong) NSArray *cars;

@end

How do I use Mantle so that my array of cars in my person model are CarModels?

score 21 · Accepted Answer · edited Jun 03 '14 at 18:19

21

Ah figured it out. I needed to add a private method:

+ (NSValueTransformer *)carsTransformer
{
    return [NSValueTransformer mtl_externalRepresentationArrayTransformerWithModelClass:[CarModel class]];
}

and make sure I used:

[PersonModel modelWithExternalRepresentation:dict];

edited Jun 03 '14 at 18:19

Kyle Clegg

38,547
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answered Dec 14 '12 at 18:45

Mr Rogers

6,091
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6

This method is deprecated, the new one is: [NSValueTransformer mtl_JSONArrayTransformerWithModelClass:[CarModel class]]; – KrauseFx Aug 23 '13 at 19:14
It didn't seem to drop into the property transformer method until I parsed the JSON like this: MyModelClass * myModel = [MTLJSONAdapter modelOfClass:[MyModelClass class] fromJSONDictionary:jsonDictionary error:&error]; – slim Aug 23 '13 at 22:27
Don't forget `#import ` – Kyle Clegg Jun 03 '14 at 18:20
3

now you have to use [MTLJSONAdapter arrayTransformerWithModelClass:[CarModel class]]; – gaRik Oct 14 '15 at 16:59

score 13 · Answer 2 · answered Jul 24 '13 at 08:59

13

+[NSValueTransformer mtl_externalRepresentationArrayTransformerWithModelClass:] is deprecated. The new API is +[NSValueTransformer mtl_JSONArrayTransformerWithModelClass:].

After switching to the new API, the models can be initialized with the default initializers provided by, e.g., MTLJSONAdapter.

answered Jul 24 '13 at 08:59

Manuel Binna

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2

Both of these are now deprecated, see http://stackoverflow.com/a/30735107/1652402 – Daniel Galasko Jun 15 '15 at 12:26

score 12 · Answer 3 · answered Jun 09 '15 at 14:33

A note on:

[NSValueTransformer mtl_JSONArrayTransformerWithModelClass:CarModel.class];

This methods seems to now be deprecated. I'm using this new method in my code and it appears to be working just fine:

[MTLJSONAdapter arrayTransformerWithModelClass:CarModel.class];

score 4 · Answer 4 · answered Apr 22 '14 at 08:35

4

+ (NSValueTransformer *)carsJSONTransformer {
    return [NSValueTransformer mtl_JSONArrayTransformerWithModelClass:CarModel.class];
}

How to specify child objects type in an NSArray with Mantle

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