AFNetworking send array in JSON parameters of post request

Question

I'm trying to send parameters to my server via POST, and it works generally, but I can't figure out how to send JSON that contains an array as one of the parameters. Here's what I've tried:

AFHTTPClient *httpClient = [[AFHTTPClient alloc] initWithBaseURL:[NSURL URLWithString:myURL]];
NSMutableArray *objectsInCart = [NSMutableArray arrayWithCapacity:[_cart count]];
for(NSDictionary *dict in _cart)
{
    NSObject *object = [dict objectForKey:@"object"];
    NSDictionary *objectDict = @{@"product_id": [NSString stringWithFormat:@"%d",[object productID]],
                                 @"quantity": [NSString stringWithFormat:@"%d", [[dict objectForKey:@"count"] intValue]],
                                 @"store_id": [NSString stringWithFormat:@"%d", [Store getStoreID]],
                                 @"price": [NSString stringWithFormat:@"%.2f", [object price]]};
    [objectsInCart addObject:objectDict];
}
NSError *error = nil;
NSString *cartJSON = [[NSString alloc] initWithData:[NSJSONSerialization dataWithJSONObject:objectsInCart
                                                                                    options:NSJSONWritingPrettyPrinted
                                                                                      error:&error]
                                           encoding:NSUTF8StringEncoding];

if(error)
{
    NSLog(@"Error serializing cart to JSON: %@", [error description]);
    return;
}

NSDictionary *parameters = @{@"status": @"SUBMITTED",
                             @"orders": cartJSON};

NSMutableURLRequest *orderRequest = [httpClient requestWithMethod:@"POST"
                                                             path:@"/app/carts"
                                                       parameters:parameters];

AFJSONRequestOperation *JSONOperation = [[AFJSONRequestOperation alloc] initWithRequest:orderRequest];

However, I get an error when sending this JSON. Any suggestions are much appreciated!

Answer 1

I don't see where you're specifying you want to post JSON, so I'm betting you're sending Form URL Parameter Encoding, which goes like this, according to the AFHTTPClient documentation:

If a query string pair has a an NSArray for its value, each member of the array will be represented in the format field[]=value1&field[]=value2. Otherwise, the pair will be formatted as "field=value". String representations of both keys and values are derived using the -description method. The constructed query string does not include the ? character used to delimit the query component.

If your server is indeed expecting you to post JSON, add this on the second line to tell AFNetworking that:

// AFNetworking 1.0
// httpClient is a subclass of AFHTTPClient
httpClient.parameterEncoding = AFJSONParameterEncoding;

// AFNetworking 2.0
// httpClient is a subclass of AFHTTPRequestOperationManager or AFHTTPSessionManager
httpClient.requestSerializer = AFJSONRequestSerializer;

You would then remove your call to NSJSONSerialization and just put objectsInCart into the parameters dictionary.

A side note: it's normal to subclass AFHTTPRequestOperationManager or AFHTTPSessionManager (AFNetworking 2.0) or AFHTTPClient (AFNetworking 1.0) and put this type of configuration in your initWithBaseURL: method. (You probably don't want to spin up a new client for every request.)