Karl Bateman Karl Bateman - 3 months ago 18
Javascript Question

NodeJS request multiple api endpoints

Ok so I am trying to make two or more requests to API endpoints using the request module. I am rendering a HTML file and passing the returned JSON to a handlebars template using the below code:

res.render('list.html', {
title: 'List',
data: returnedJSON
}


I can then iterate over this JSON within my handlebars template fairly easily.

The problem I have, is that I am now needing to use multiple data sources where a category list will be built from a categories JSON response and a Staff list from a staff JSON response. I would like a simple solution where I can do this, but expand it to use any number of data sources.

Below is a full code snippet of what I have with one data source:

request({
url: 'https://api.com/categories',
headers: {
'Bearer': 'sampleapitoken'
}
}, function(error, response, body) {
if(error || response.statusCode !== 200) {
// handle error
} else {
var json = JSON.parse(body);
res.render('list.html', {
title: 'Listing',
data: json
});
}
});


This works great for one endpoint, but as mentioned before I now need to use multiple requests and have multiple data sources for example:

request({
url: ['https://api.com/categories','https://api.com/staff'],
headers: {
'Bearer': 'sampleapitoken'
}
}, function(error, response, body1, body2) {
if(error || response.statusCode !== 200) {
// handle error
} else {
var json1 = JSON.parse(body1);
var json2 = JSON.parse(body2);
res.render('list.html', {
title: 'Listing',
staff: json1,
categories: json2
});
}
});


I appreciate the above doesn't work like that, but I hope this can help convey what I am trying to achieve.

Thanks in advance :)

Answer

You can use the async library to map your request objects and pass them to an actual request and return all results in one callback.

var async = require("async");
var request = require("request");

// create request objects
var requests = [{
  url: 'https://api.com/categories',
  headers: {
    'Bearer': 'sampleapitoken'
  }
}, {
  url: 'https://api.com/staff',
  headers: {
    'Bearer': 'sampleapitoken'
  }
}];

async.map(requests, function(obj, callback) {
  // iterator function
  request(obj, function(error, response, body) {
    if (!error && response.statusCode == 200) {
      // transform data here or pass it on
      var body = JSON.parse(body);
      callback(null, body);
    } else {
      callback(error || response.statusCode);
    }
  });
}, function(err, results) {
  // all requests have been made
  if (err) {
    // handle your error
  } else {
    console.log(results);
    for (var i = 0; i < results.length; i++) {
      // request body is results[i]
    }
  }
});

However a simpler way would to leverage promises, this can be done with bluebird and promisifying the request lib, or use the already promisified request lib request-promise. You'll still want to include a promise/A+ lib to map the results asynchronously.

var Promise = require("bluebird");
var request = require('request-promise');

// create request objects
var requests = [{
  url: 'https://api.com/categories',
  headers: {
    'Bearer': 'sampleapitoken'
  }
}, {
  url: 'https://api.com/staff',
  headers: {
    'Bearer': 'sampleapitoken'
  }
}];

Promise.map(requests, function(obj) {
  return request(obj).then(function(body) {
    return JSON.parse(body);
  });
}).then(function(results) {
  console.log(results);
  for (var i = 0; i < results.length; i++) {
    // access the result's body via results[i]
  }
}, function(err) {
  // handle all your errors here
});

It's important to note that all latest versions of node and browsers support Promises out of the box and this can be implemented without external libraries.