Custom model class for every element. by qdvictory · Pull Request #616 · jsonmodel/jsonmodel

qdvictory · 2018-03-01T08:34:29Z

In the same location, if there are multiple models, this method can be used to output the corresponding model.

Such as,
[{ "background": "#ff0000", "foreground": "#0000ff", "typeField": "picture" }, { "body": "#ff0000", "tire": "#0000ff", "typeField": "car" }]

there is a list, it has many types. So you want convert to model, it's very inconvenient.

Now, you can create a super class and subclass like:

@interface MultipleModel : JSONModel
@property (strong, nonatomic) NSString *typeField;
@end

@interface MultiplePicModel : MultipleModel
@property (strong, nonatomic) NSString *background;
@property (strong, nonatomic) NSString *foreground;
@end

@interface MultipleCarModel : MultipleModel
@property (strong, nonatomic) NSString *body;
@property (strong, nonatomic) NSString *tire;
@end

---------------------------------------------
@class MultipleCarModel;
@class MultiplePicModel;

@implementation MultipleModel

+ (Class)classForModel:(NSDictionary *)dict
{
	if ([[dict valueForKey:@"typeField"] isEqualToString:@"picture"]) {
		return [MultiplePicModel class];
	}
	else if ([[dict valueForKey:@"typeField"] isEqualToString:@"car"]) {
		return [MultipleCarModel class];
	}
	return [self class];
}
@end

@implementation MultiplePicModel

@end

@implementation MultipleCarModel

@end

create model like before:

NSArray *array = [MultipleModel arrayOfModelsFromDictionaries:self.jsonArray error:&error];
NSLog(@"%@",array);

output:

(
<MultiplePicModel> 
   [foreground]: #0000ff
   [typeField]: picture
   [background]: #ff0000
</MultiplePicModel>,
<MultipleCarModel> 
   [tire]: #0000ff
   [typeField]: car
   [body]: #ff0000
</MultipleCarMode>
)

billinghamj · 2018-03-01T08:53:37Z

Ah okay, interesting. This is basically an implementation of the polymorphism support.

This is actually something which has been discussed quite a lot. So far, we have always suggested implementing a class cluster by overriding the initWithDictionary:error: method.

See: #229 (comment)

That being said, it has been mentioned many times, so I do agree that we should consider it.

Some important factors for me:

it would need to work the same way for direct properties on objects, for arrays, for dictionaries, and possibly even for root objects
it must not conflict with the “class for collection elements” method

heistings · 2018-03-01T09:22:12Z

@billinghamj It looks good for me.

Implementing a class cluster by overriding the - initWithDictionary:error: method means allocating a superclass instance and then allocating a subclass one.

So, class method is crucial to this issue. Another similar way to avoid allocating twice is wrapping the + modelWithDictionary:error: method, and implementing a class cluster by overriding the method.

heistings · 2018-03-01T09:55:18Z

@qdvictory

So is it seems a good idea to use the + modelWithDictionary:error: method?

qdvictory · 2018-03-01T10:13:28Z

@billinghamj
yea,
it's can't support root objects.
it's only can be use like:

NSDictionary *d = @{@"typeField":@"picture",@"background":@"aaa",@"foreground":@"ccc"};
MultipleModel *m = [[[MultipleModel classForModel:d] alloc] initWithDictionary:d error:nil];

output:
<MultiplePicModel> 
   [foreground]: ccc
   [typeField]: picture
   [background]: aaa
</MultiplePicModel>

it must not conflict with the “class for collection elements” method

I added a bit is this PR.

qdvictory · 2018-03-01T10:26:27Z

@heistings
I think it's a good idea. I will implement it later.

qdvictory · 2018-03-01T11:29:02Z

@heistings @billinghamj
now support modelWithDictionary:error:

NSDictionary *d = @{@"typeField":@"picture",@"background":@"aaa",@"foreground":@"ccc"};
MultipleModel *m = [MultipleModel modelWithDictionary:d error:nil];

output:
<MultiplePicModel> 
   [foreground]: ccc
   [typeField]: picture
   [background]: aaa
</MultiplePicModel>

heistings · 2018-03-01T12:19:19Z

@qdvictory It looks good for me. Overriding the + classForModel: method is easier than overriding the - initWithDictionary:error: method.

qdvictory added 3 commits March 1, 2018 16:19

Custom model class for every element.

f42f637

add test

b9560c3

merge class

1a4e53f

support classForCollectionProperty:

5e52346

add lost [

2b3c7d5

qdvictory added 2 commits March 1, 2018 19:25

add method modelWithDictionary:error:

b7e116e

add test

a67d058

add test for classForCollectionProperty

5145617

qdvictory added 2 commits March 28, 2018 18:10

change root project not be parsed.

0c926fd

fix class method.

582cea9

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Custom model class for every element.#616

Custom model class for every element.#616
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qdvictory commented Mar 1, 2018

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heistings commented Mar 1, 2018 •

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qdvictory commented Mar 1, 2018

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heistings commented Mar 1, 2018 •

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