How to return value from node to origin (angular2 request)

Question

I have code in my nodejs instance that receives a post request (successfully) and also shows arguments sent via json (I'm requiring body-parser in the server side). As soon as the post requests is received I immediately perform return "testing"; to check on whether the value is being returned successfully. However, my angular2 callback (done as shown) does not fire or display any logs. Any idea on why?

  var to_send = JSON.stringify({"test": argument});

  var headers = new Headers();
    headers.append('Content-Type', 'application/json');

   this.http
    .post('http://localhost:8080/', 
      to_send, {
        headers: headers
      })
    .map((res) => res.json() )
    .subscribe(
      (response) => { console.log("Success Response" + response)},
      (error) => { console.log("Error happened" + error)},
      () => { this.parseResponse(res); }
    );

The function parseResponse simply console.logs("something returned");

EDIT:

Here is how my code is now, still failing (no log inside parseResponse is triggered):

var to_send = JSON.stringify({"test": argument});

  var headers = new Headers();
    headers.append('Content-Type', 'application/json');

  this.http
    .post('http://localhost:8080/', 
      to_send, {
        headers: headers
      })
    .map((res) => res.json() )
    .subscribe(
      (response) => { console.log("Success Response",response)},
      (error) => { console.log("Error happened",error)},
      () => { this.parseResponse(res); }
    );

And in my server I am returning the following:

var to_return = {};

to_return["message"] = "success";

return to_return;

Still, it does not work at all. Any idea on why? parseResponse is a simple log "feedback received"...

Andrei Zhytkevich · Accepted Answer · 2016-07-13T15:01:44.670

2

You do

this.http...
  .map((res) => res.json() )

By this you convert response to json, since it's not json, it fails. You can use method text() instead to get string:

.map((res) => res.text())

Or you can return an object from back-end:

return {result: "testing"}

and read field result inside subscribe

Update:

You can output the res in map method to see what it really contains:

.map((res) => {
  console.log(res);
  return res.json();
})

One more thing: call this.parseResponse(res); res doesn't exist in this scope. It will be undefined inside parseResponse

edited Jul 13 '16 at 15:01

answered Jul 04 '16 at 18:39

Andrei Zhytkevich

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updated. please also add the code of `parseResponse` and try a `console.log` before `this.parseResponse` – Andrei Zhytkevich Jul 13 '16 at 15:02

score 0 · Answer 2 · answered Jul 07 '16 at 21:08

Try this, self.parseResponse(res); :

...
 let self = this;
 this.http
    .post('http://localhost:8080/', 
      to_send, {
        headers: headers
      })
    .map((res) => res.json() )
    .subscribe(
      (response) => { console.log("Success Response",response)},
      (error) => { console.log("Error happened",error)},
      () => { self.parseResponse(res); }
    );

score 0 · Answer 3 · edited Jun 20 '20 at 09:12

I doubt your server code. Have you verified that server is really sending any response. and it is really reaching your client side.?

return to_return;

You have not mentioned exactly where your server code is running. This doc clearly says the response object already created by core HTTP module and it always passes it along with request object. So Ideally you just have to use response object. and call its API like send.

but you have not at all shown any code where you use response object.

How to return value from node to origin (angular2 request)

EDIT:

3 Answers3