Function gets called twice

[romuye123]

The function gets called twice even if I execute the URL only once.. What could be the problem ?

Following is my code:

rest.function("status",espstatus);
.
.
.
.

int espstatus(String command){
  Serial.print("Command recd: ");
  Serial.println(command);
  return 1;
}

This is how i call the url from browser: http://esp-ip-address/status?params=testf123

And following is the output on my Serial monitor:

Command recd: testf123
Command recd: testf123

[marcoschwartz]

Hello,

This might happen when using aREST in your browser, as browsers usually send several requests to the server. If you are using it from a web app however this won't happen. Is this an issue for you?

[romuye123]

Yes i am accessing the URL from web browser. Did not tried from app yet, will try and let you know the feedback.

[adadgio]

Is there any update on this issue ? I think it's still quite a problem for a Rest (;-)) like API not to be called properly from browser. Solution, skip OPTIONS request in the source code maybe ?

[marcoschwartz]

Still working on it - I found the source of the problem but it's hard to fix without breaking the compatibility with older boards like the Arduino Uno.

[pta-]

Found out that in chrome it come twice, but in edge only once. First time when I liked edge for a short time :)

[JLartigaud]

Hello @marcoschwartz, maybe you could create a branch for a working version with earlier versions ? Really impressed by the aRest library btw 👍

[pkerspe]

I could "solve" the issue of duplicate function calls in Chrome (when directly calling using GET request from the browser URL field) by registering a second function for requests to "favicon.ico": rest.function("favicon.ico", favIcon); Just create a handler function that returns just anything for this call. Once I set this up I do not get duplicate calls anymore to my other rest endpoints. Maybe this helps one or the other. Obviously this does not help for OPTIONS requests.

[JLartigaud]

Haha, excellent! Didn't think about the favicon chrome call... Thank you for this really useful hint 👍

[pkerspe]

I created a fork that handles OPTIONS calls by directly sending a hopefully proper OPTIONS response (RC = 204, correct headers and no content). Use at your own risk :-) https://github.com/pkerspe/aREST

I changed the aRest.h file only, basically added a function to set the OPTIONS response headers in line 309 (please note: I followed the approach of the author to use : Access-Control-Allow-Origin: * even though this is not a good practice in regards to security!)

void send_options_http_headers(){
	addToBuffer(F("HTTP/1.1 200 OK\r\nAccess-Control-Allow-Origin: *\r\nAllow: POST, GET, OPTIONS\r\nAccess-Control-Allow-Methods: POST, GET, OPTIONS\r\nAccess-Control-Max-Age: 86400\r\n\r\n"));
}

and a check for OPTIONS request type in line 864:

if (answer.startsWith("OPTIONS")){
	state = 'x'; //not sure about this state parameter, I just chose a value that seemed ok
	command = 'o'; //this is a new command type, that has not been used before
	return;
}

at at last a check for the new command type 'o' (which I added) in line 1096:

 if (command == 'o'){ //checking for the new command type here
  	resetBuffer(); //clear output buffer, might not be needed, just wanted to be sure nothing is sent except for the headers
  	send_options_http_headers(); //send proper preflight-request response headers
  	return true;
  }

That's basically it. Since I only use direct http rest api calls I did not test if it has any side effects on the rest to the module (pubsub calls etc.), unfortunately the inline doc is not very good, so I had to guess a bit if what I was doing was ok :-)

[marcoschwartz]

@pkerspe Thanks for your work! Indeed I know it's a nasty bug, basically I am mostly using it with direct REST calls from apps in Node.js so the favicon issue doesn't appear :)

Could you actually submit a pull request with your changes? That would be awesome!

[nenadvkc]

@marcoschwartz The function still gets called twice when using aREST in the browser, is there a solution for this problem? is code that @pkerspe made, merged?

[nenadvkc]

@marcoschwartz Actually rest.function("favicon.ico", favIcon); works fine for me, sry :)