pass a variable from a function to parent scope using promises or any other suitable way of doing it

Question

How do I pass the value of var flower from inside form.parse() into response.write() so that I can output it?

Answers to similar questions suggest using promises however if that's the way to do it I would appreciate some help in how to apply a promise in this case

var formidable = require("formidable");
function upload(response, request) {
       var form = new formidable.IncomingForm();
       form.on('fileBegin', function(name, file, flower) {
            file.path = './uploads/' + file.name;
            var flowerImage = file.name ;
       });

      form.parse(request,  function(error, fields, files ) {
      });

      response.writeHead(200, {"Content-Type": "text/html"});
      response.write("image name is " + flowerImage);
      response.end();
  }

possible duplicate of [How to return the response from an asynchronous call?](http://stackoverflow.com/questions/14220321/how-to-return-the-response-from-an-asynchronous-call) — ben, Jul 06 '15 at 09:50
managed to solve by thinking about it in a different way and rephrasing the question and got some help here http://stackoverflow.com/questions/31246875/how-to-pass-the-node-response-stream-object-into-an-event-handler-function?noredirect=1#comment50492233_31246875 — jojojohn, Jul 06 '15 at 15:04

Khalid · Answer 1 · 2015-07-06T10:47:40.300

1

You just need to return the response on the Callback itself

function upload(response, request) {

       var form = new formidable.IncomingForm();

       form.on('fileBegin', function(name, file, flower) {
            file.path = './uploads/' + file.name;
            var flowerImage = file.name ;
            this.writeHead(200, {"Content-Type": "text/html"});
            this.write("image name is " + flowerImage);
            this.end();
       }.bind(response));

  }

edited Jul 06 '15 at 10:47

answered Jul 06 '15 at 09:51

Khalid

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thanks for your answer, I tried this. For some reason it cannot access the response object from inside the form.on() function, I thought n javascript variables can access values in the parent function but it doesn't seem to be doing it here... – jojojohn Jul 06 '15 at 10:03
take a look to the update, I used the `Function.prototype.bind` method to set the response as the context of the callback – Khalid Jul 06 '15 at 10:48
thanks.. I got really excited about this answer but I'm still not able to get the variable into the response object although I must be getting closer.. – jojojohn Jul 06 '15 at 11:19
I reworded the question and reposted using your answer and it is solved now - thanks for you help .. http://stackoverflow.com/questions/31246875/how-to-pass-the-node-response-stream-object-into-an-event-handler-function?noredirect=1#comment50492233_31246875 – jojojohn Jul 06 '15 at 15:03

score 0 · Answer 2 · edited May 23 '17 at 12:29

0

declare the var flowerImage next not the var form

EDIT: My bad... flowerImage is created using an async call... This has been answered many times.

See How do I return the response from an asynchronous call?

edited May 23 '17 at 12:29

Community

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answered Jul 06 '15 at 09:48

ben

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1
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are you saying I should use promises? Any advice in how to implement one in this case ? – jojojohn Jul 06 '15 at 10:34

pass a variable from a function to parent scope using promises or any other suitable way of doing it

2 Answers2