callbacksModelAnswerLearning1

appLearningMA.js

// dealing with the Location
var location = require('./learningLocation.js');
// dealing with the Weather
var weather = require('./learningWeather.js');
// test the script.
// this works!!

location(function(userLocation){
	console.log('Location is: ', userLocation);
}); 

// test the script
// this doesn't work!!!
weather(location,function(weatherData){
	console.log('Weather is: ', weatherData);
});

learningLocation.js

// learningLocation
// NB: Location is not dependent on any user input
// Location is obtained from the IP address

module.exports = function(callback){

	// define variables
	var url = "http://ipinfo.io";
	var request = require('request');

	// Notification
	console.log('Obtaining the location...');

	// Logic
	request({
		url: url,
		json: true
	}, function(error, response, body){
		if(error){
			callback('');
		} else {
			callback(JSON.stringify(body, null, 4));
		}
	});
};

learningWeather.js

module.exports = function(location, callback){
	// define variables
	var request = require('request');
	var encodedLocation = encodeURIComponent(location);
	var url = 'http://api.openweathermap.org/data/2.5/weather?q=' + encodedLocation + '&appid=a0405ca935c126bca3f178e0230f75b5&units=metric';


	// Check if no location is provided
	if (!location){
		return callback('No location provided'); // ie end the program here
	}

	// Notify the user
	console.log('Fetching the weather data...');

	// Apply logic
	request({
		url: url,
		json: true
	},function(error, response, body){
		if(error){
			callback('Unable to fetch the weather data!');
		} else {
			//console.log(JSON.stringify(body,null, 4));
			callback('In city: ' + body.name +  ' the temperature is:  ' + body.main.temp + ' deg C.');
		}
	});
};

learningWeatherExpt1.js

// define variables
var request = require('request');
var encodedLocation = encodeURIComponent('Sutton');
var url = 'http://api.openweathermap.org/data/2.5/weather?q=' + encodedLocation + '&appid=a0405ca935c126bca3f178e0230f75b5&units=metric';

// Notification.
console.log('LearningWeatherExpt1: Getting weather data...');

// Apply logic
request({
	url : url,
	json: true
}, function(error, response, body){
	if(error){
		console.log('Unable to fetch weather data!!')
	} else {
		console.log(JSON.stringify(body, null, 4));
		console.log("Town: " , body.name + ': Country ' + body.sys.country + ': Temperature: ' + body.main.temp + ' deg C.');
	}
});

Hey,

The best way to debug this would be to following the execution of the application. On line 14 of appLearningMA.js the problem is not with the function that's called. The problem is with that first argument, location.

On line 14 the location function is getting passed in, not a string location like userLocation. That's why the program is crashing.

- Andrew