a strict version of modelOfClass:fromJSONDictionary: ?

[knlr]

Consider I'm using modelOfClass:fromJSONDictionary: and I want to be able to tell if something in the mapping went wrong, like a missing key or a type error (e.g. property is a NSNumber but it's a string in the JSON and an NSString is assigned).

I could write validation functions in my model classes checking the validity of each property. Or there could be a 'strict' version of modelOfClass:fromJSONDictionary that returns nil and gives an error when a key was not found or a wrong type is assigned to a property. Is it possible? If so, would you add this?

[jspahrsummers]

AFAIK the method should already have this “strict” behavior. Are you seeing something different?

[knlr]

Yes I do. Maybe I didn't make myself clear. When a mapped key is not contained in the JSON, the mapped property will be nil, the model object will be created and the error is nil. Example:

@interface MTLTweet : MTLModel <MTLJSONSerializing>

@property (nonatomic) NSString* text;
@property (nonatomic) NSString* userName;
@property (nonatomic) NSString* profileImageURL;

@end

@implementation MTLTweet

+ (NSDictionary *)JSONKeyPathsByPropertyKey {
        return @{
             @"text": @"Text", 
             @"userName": @"user.name",
             @"profileImageURL": @"user.profileimageurl" // intentionelly misspelled 
             };
}

@end

the NSDictionary (abbreviated):
(lldb) po response

{        
    text = "Piraeus Egypt has highest retail banking portfolio growth for 2014 http://t.co/t4YI8M7bee #DaytonFinancialAdvice";    
    user =     {    
        name = "John Stamos";
        "profile_image_url" = "http://pbs.twimg.com/profile_images/378800000731641435/275da1fb86bcb0d8b55a9da640881643_normal.jpeg";
    };
}

instantiating the model object:

MTLTweet* tweet = [MTLJSONAdapter modelOfClass:MTLTweet.class
                            fromJSONDictionary:response
                                         error:&error];

(lldb) po tweet
<MTLTweet: 0xc767c80> {
    profileImageURL = "<null>";
    text = "Piraeus Egypt has highest retail banking portfolio growth for 2014 http://t.co/t4YI8M7bee #DaytonFinancialAdvice";
    userName = John Stamos;
}

I want the tweet to be nil if one of the properties is nil.

[robb]

I could write validation functions in my model classes checking the validity of each property.

In this case, -validateProfileImageURL:error: would never be invoked. I'd recommend overriding -[MTLModel validate:] and check profileImageURL != nil there.

[danielgalasko]

So @knlr just to confirm, you would like to specify a list of non nullable properties on an MTLModel subclass?

Like a MTLJSONCompulsoryKeyPathsSerializing protocol that the JSONAdapter would use as an added step during serialization?

[github-actions]

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