API Request returns correctly, but is null in the callback function

Question

I am using npm Express and Request modules to obtain movie information via an API:

var express = require("express");
var app = express();
var request = require("request");

app.get("/results", function(req, res){
    console.log(getBody("http://www.omdbapi.com/?s=The+Shining&page=1&apikey=myKey"));
});

function getBody(requestString){
    request(requestString, function(error, response, body){
        return body;
    };
}

I removed error checking on the request here for the sake of readability.

Within the request, logging "body" shows that the request did return proper JSON. However, when I return to app.get, the value of the logging is undefined.

Is it not possible to return this value to app.get's callback function?

Andy · Accepted Answer · 2017-07-23 17:48:47Z

1

request is an async function, so you need to use one of the many techniques (callback, promise etc) to return the data successfully.

Here's an example with a callback:

app.get("/results", function(req, res) {
  getBody(endpoint, function (data) {
    console.log(data);
  });
});

function getBody(endpoint, callback) {
  request(endpoint, function(error, response, body) {
    callback(body);
  });
}

And an example using a promise:

app.get("/results", function(req, res) {
  getBody(endpoint).then(function (data) {
    console.log(data);
  });
});

function getBody(endpoint, callback) {
  return new Promise(function (resolve, reject) {
    request(endpoint, function(error, response, body) {
      if (error) reject('Request failed');
      resolve(body);
    });  
  });
}

edited Jul 23, 2017 at 17:48

answered Jul 23, 2017 at 17:41

Andy

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