Sending a JSON via POST in NSURLRequest

Question

I have a problem with sending a JSON to a Server with REST API. This is the code i use:

NSString *jsonPostBody = [NSString stringWithFormat:@"'json' = '{\"user\":{\"username\":"
                          "\"%@\""
                          ",\"password\":"
                          "\"%@\""
                          "}}'",
                          [username stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding],
                          [password stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];       
NSData *postData = [jsonPostBody dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];
NSString *apiPathParams = [NSString stringWithFormat:@"%@",
                           @"getUser"
                           ];

NSURL *url = [NSURL URLWithString:[[apiPath retain] stringByAppendingString:apiPathParams]];    
NSMutableURLRequest* request = [NSMutableURLRequest requestWithURL:url
                                                       cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
                                                   timeoutInterval:180.0];
[request setHTTPMethod:@"POST"];
[request setHTTPBody:postData];
NSString* postDataLengthString = [[NSString alloc] initWithFormat:@"%d", [postData length]];
[request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
[request setValue:postDataLengthString forHTTPHeaderField:@"Content-Length"];
[self internalRequest:request];

This is what the API would look like, if it was a html form:

<form method="post" action="someAPI-URL">
<input name="json" value="{"user":...}" />
</form>

This is what my POST Data looks like when i add it to the request:

json={"user":{"username":"someUser","password":"somePassword"}}

For a reason I don't know the POST Data does not arrive at the server. Have i done something wrong with the formatting of the dataString? How exactly must i format my dataString so that it matches the String a form as shown above would deliver to the server?

Any help would be highly appreciated.

P.S. I would rather not use ASIHttpRequest, since i took over the project from somebody else an every other request works fine, except this post-request. So changing this whole bulk to an other connection framework would be very time consuming.

Here is the internalRequest Method's sourcecode

NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:req delegate:self];
NSMutableDictionary *di = [NSMutableDictionary dictionaryWithObject:[[NSMutableData alloc] init] forKey:@"receivedData"];   
[di setObject:[NSString stringWithFormat:@"%i",identifier] forKey:@"identifier"];
if (delegate == nil) 
{ 
    delegate = self;         
}
[di setObject:delegate forKey:@"delegate"];

CFDictionaryAddValue(connectionToInfoMapping, connection, di)

Solution

since you try to submit a HTTP POST header like

json={"user":{"username":"%@","password":"%@"}},

this example is fully qualified to end up in confusion.

It's a mixture of application/x-www-form-urlencoded for the whole body and application/json for the value.

Maybe a way to resolve this:

You'll probably need to adjust that HTTP header:

 [request setValue:@"application/x-www-form-urlencoded" 
forHTTPHeaderField:@"Content-Type"];

due to an encoding of the JSON part (value) of the HTTP body:

[request setHTTPBody:[[jsonPostBody stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding]
                      dataUsingEncoding:NSUTF8StringEncoding 
                   allowLossyConversion:YES]];    

where stringByAddingPercentEscapesUsingEncoding is objective c jabberwocky for the PHP equivalent urlencode.

HTH

Comments

[Maverick1st]

Well, since JSON is nothing more than a special String Representation of a certain context which can be transformed to Dictionarys and Arrays very easily I don't think this will make a difference. Especially since i used POST Requests earlier without a JSON framework. But I'll give it a try. May be it works :)

[Maverick1st]

You are my hero of the day. Works like a charm. No i only have to mess up the guy who gave me the interface description... :)