Using REST API on iOS returns 'Entity can't be empty'

General
1

I’m trying to create a new data object using the REST API on iOS, as follows:
NSString *url= @“http://api.backendless.com/v1/data/MyData”;
NSString *dataString= @"{data:“some data”}";
NSData *data = [dataString dataUsingEncoding:NSUTF8StringEncoding];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
[request setURL:[NSURL URLWithString:url]];
[request setHTTPMethod:@“POST”];
[request setValue:<my-app-id> forHTTPHeaderField:@“application-id”];
[request setValue:<my-secret-key> forHTTPHeaderField:@“secret-key”];
[request setValue:@“REST” forHTTPHeaderField:@“application-type”];
[request setValue:[NSString stringWithFormat:@"%d", [data length]] forHTTPHeaderField:@“Content-Length”];
[request setHTTPBody:data];
NSData *responseData= [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
NSLog( @"%@", [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding] );
Here’s the output:
2013-11-06 17:54:59.281 XXXXXX[6982:1403] Entity can’t be empty

2

Thanks Mark, that worked. I’m now having a problem with the update:

&lt;body&gt;


	&lt;h1&gt;Action not found&lt;/h1&gt;




	&lt;p id=&quot;detail&quot;&gt;

		For request 'POST /v1/data/MyData/&lt;objectID&gt;

	&lt;/p&gt;




&lt;/body&gt;
3

Hi Russell,

Any chance you could post the code which makes the request?

Regards,
Mark

4

NSString *url= [NSString stringWithFormat:@“http://api.backendless.com/v1/data/MyData/DCF92457-…”];

    NSString *dataString= @"{\"data\":\"some updated data\"}";




    NSData *data = [dataString

dataUsingEncoding:NSUTF8StringEncoding];

    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];

    [request setURL:[NSURL URLWithString:url]];

    [request setHTTPMethod:@"POST"];

    [request setValue:@"1775476F" forHTTPHeaderField:@"application-id"];

    [request setValue:@"937F8ED7" forHTTPHeaderField:@"secret-key"];

    [request setValue:@"REST" forHTTPHeaderField:@"application-type"];

    [request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];

    [request setValue:[NSString stringWithFormat:@"%d", [data length]] forHTTPHeaderField:@"Content-Length"];

    [request setHTTPBody:data];




    NSError *error = nil;

    NSURLResponse *response = nil;

    NSData *responseData= [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
5

Make sure to use HTTP PUT. I think your code is doing HTTP PUT. So change this:

[request setHTTPMethod:@"POST"];

to this:

 [request setHTTPMethod:@"PUT"];
6

make sure to add the following line of code and it will work:

 [request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];

Cheers,
Mark