Sending few post request using
- (AFHTTPRequestOperation *)POST:(NSString *)URLString
parameters:(id)parameters
success:(void (^)(AFHTTPRequestOperation *operation, id responseObject))success
failure:(void (^)(AFHTTPRequestOperation *operation, NSError *error))failure
I want to perform one get request once all of the above request have processed so I have created AFHTTPRequestOperation and adding dependency as
for (AFHTTPRequestOperation *operation in manager.operationQueue.operations ) {
[AFHTTPRequestOperationObject addDependency:operation];
}
[manager.operationQueue addOperation: AFHTTPRequestOperationObject];
But the operation is performed before the completion of existing post request.
You shouldn't use NSOperation dependencies to solve this problem. In your case, later operations rely on processing with completionBlock but NSOperationQueue and AFNetworking both consider that work a side effect.
completionBlock is:
the block to execute after the operation’s main task is completed.
(my emphasis).
In the case of AFHTTPRequestOperation, "the operation’s main task" is "making an HTTP request". The "main task" doesn't include parsing JSON, persisting data, checking HTTP status codes, etc. - that's all handled in completionBlock.
To perform one request after other requests have processed, you'll need to make that request in the completion handler, once you've verified you have all the data you need to proceed.
While using OperationQueues, it is not necessary that the responses will be received in the same order as the requests made. You will have to make sure that you make the GETrequest after complete execution of multiple POST requests. This explains the process to perform the operations serially with a completionHandler (which in your case should be the GET request that you want to execute at the completion of the POST requests.)
It appears that AFHTTPRequestOperation(s) complete as soon as the HTTP call is made and returns. The success and failure blocks are called after these operations are complete. So if you have NSOperation A dependent on B which is a AFHTTPRequestOperation then you may see B run, followed by A, followed by B's success block. Seems to work if you create a "finished" operation and make A dependent on it. Then have B enqueue the "finished" operation for running when B calls its success or failure block. The "finished" operation in effect signals A that B has done all you wanted it to do.
Related
I tried AFHTTPRequestOperation objects combined with other NSOperation objects placed into a queue. But now I know that in AFHTTPRequestOperation only requests are performed in correct order (not response processing blocks).
I don't need the correct order of requests but I need to handle their responses in a correct order and send a "success" notification at the end. If one of the steps is failed then cancel the sequence. The only idea I have is the following:
NSBlockOperation *operation = [NSBlockOperation blockOperationWithBlock:^{
//synchronous request1
...
//handle request1 response
...
//synchronous request2
...
//handle request2 response
...
//send notification about success or failure
...
}];
It looks crazy but correct. Is this code correct? Could you advice anything better?
You're right. The basic thing is that you have to synchronize the responses based on completion. and it does not matter if you use sync or async way. scheme: request(sync/async) -> completion -> request 2 (sync/async) -> completion...etc..
I have a project which you can imagine is like the Facebook app and I'm having trouble grasping how to organize it with RestKit and handle tokens since I'm a RestKit beginner.
This is what I got so far:
Core Data NSManagedObject classes, for each of them I added a category called REST that has functions to provide RKObjectMapping and RKRouteSet
custom RKObjectManager subclass which handles setting up headers, MIME types, setting authorization headers and Core Data stores
RKObjectRequestOperation subclass
If you have organizational advice shoot, but my main question is how do I implement automatic token refreshing after recieving a 401 HTTP status code and firing the failed request again with a fresh token?
I started by overriding the metod in my RKObjectRequestOperation subclass:
- (void)setCompletionBlockWithSuccess:(void ( ^ ) ( RKObjectRequestOperation *operation , RKMappingResult *mappingResult ))success
failure:(void ( ^ ) ( RKObjectRequestOperation *operation , NSError *error ))failure
So now I can intercept a 401 response, but now I have to make another call to refresh the token and then re-enqueue the failed operation with a fresh token, please advise how to do that.
I generally wouldn't use a custom RKObjectRequestOperation if you are using an object manager. I'd handle it at the object manager level.
In the object manager you can override each of the main request methods (which are supplied with success and failure blocks). You can implement these methods to call super but substituting the success and failure blocks with new versions which add some logic before calling the supplied versions.
Now, the additional logic would be a check of the response status. If it shows a token refresh is required it can be actioned and then the object manager can trigger a new load, using the parameters supplied in the first request.
Also, you shouldn't re-queue an operation unless the documentation states that it is supported as some operations won't work the second time they're executed...
I couldn't find a reasonable answer so i'll ask for this specific case.
I must perform a http call (setting a specific header as a token value) and parse the returned json. The json can both return a "operation completed" message or a "token expired" message.
In case of token expired i must execute another http call which will provide me the refreshed token, set the token as header and re-execute the original http call.
I decided to adopt this solution: from the main thread, i'm gonna create another thread using
...
dispatch_async(feedQueue
...
and in this thread i'm gonna performing the above descripted calls as synchronous calls using
...
[NSURLConnection sendSynchronousRequest:urlRequest
...
and only at the end of the flow i call the main thread passing results to a block.
This way code is simple, easy to read, it has a linear flow, it is completely scoped inside a unique thread, and i don't mess with delegates and different "finite-states" to manage calls chain.
But i'm not sure if this is the best approach for my specific use-case as i've read similar questions where people suggest to adopt asynchronous calls, using both finite-states or NSOperation instances, but it seems to me that both these approaches based on asynchronous calls, are not the best solutions for a http calls chain.
What is the best approach? How can i correctly implement a chain of http call?
The correct way to set this up would be to use asynchronous calls for NSURLConnection. In the connectionDidFinishLoading you will intercept the connection that just finished and launch the next chained http connection.
Setup a private variable called _connection1;
So basically, you will do something like this
NSURLRequest * request1 = ...
_connection1 = [[NSURLConnection alloc] initWithRequest:request1 delegate:self];
In the
- (void)connectionDidFinishLoading:(NSURLConnection *)connection{
if([connection isEqual:_connection1]){
NSURLRequest *request2 = ...
_connection2 = [NSURLConnection...]
}
if([connection isEqual:_connection2]){
NSURLRequest *request3 = ...
_connection2 = [NSURLConnection...request3 ]
// And so on ....
}
}
AFJSONRequestOperation has a successBlock block for when the request succeeds, but there is no way to set the "Authentication Block" other than on the operation itself, so if that fails then there is no way to send back to the caller of the AFJSONRequestOperation. Is that correct, or am I missing something?
I would expect to be able to tell the caller that the whole operation failed because authorization failed.
Actually the method takes two block as a parameters success and failure
AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:successBlock failure:failureBlock];
So in the failure block you should be able to notify the caller of the failure
The API I'm developing against requires me to present an authentication token in a custom HTTP header. This token expires every few minutes, and could happen while the user is still within the app as long as they have been idle long enough. When the token has expired I receive a 403 response but I only find out after attempting a request.
What's the best way to get RestKit to automatically reauthenticate and retry the request so I don't have to put in this logic everywhere I make a request? Responses to similar questions have suggested using the RKRequestDelegate protocol or the RKObjectLoaderDelegate protocol but unfortunately these are no longer part of RestKit (as of 0.20).
Any idea what the "correct" approach should be now? Should I be subclassing RKObjectManager and tacking on a retry to each of the request operations or should I provide a custom HTTPOperation or HTTPClient class or is there some better approach altogether? Thanks!
Catch it in Failure block , and check for the status code and re-do the authentication
RKObjectRequestOperation *requestOp = [[RKObjectRequestOperation alloc] initWithRequest:request responseDescriptors:#[getObjResp]];
[requestOp setCompletionBlockWithSuccess:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
....
}
} failure:^(RKObjectRequestOperation *operation, NSError *error){
// Here your status code check
// Here your retry-code
}