Using a module's internal function as a callback in the "request" operation

Question

Using a module's internal function as a callback in the "request" operation

Within my primary code, I execute the following:

var module = require('./module')

module.FooA(module.FooB);

The contents of module.js are as follows:

var request = require('request'); //using npm "request"

exports.FooB = function(data){ /*operations on data here*/ };

exports.FooA = function(callback){

    var url = some_link;

    request(url, function (error, response, body) {
        if (!error && response.statusCode == 200) {
            callback(body);
        };
    });

};

An issue arises where callback(body) does not execute even when the conditions are met. While using var result = request(url) and then exports.FooB(result) seems to resolve the problem, it is evident that this approach lacks the asynchronous nature of a callback function and may lead to complications.

What would be the correct method for defining a callback function in such a scenario? Is there a need for it at all, or could it possibly be synchronous and overlooked?

node.js express module request asynccallback

Answer 1

Answer №1

Ensure to utilize the first function callback parameters for handling errors, as this is a default practice in the core of node.js and can be beneficial for your project functions.

Following @ShanSan's advice, make use of console.log, console.error, or console.trace for debugging purposes.

For instance:

var request = require('request'); //using npm package "request"

exports.FooB = function(error, data){ /*operations on data go here*/ };

exports.FooA = function(callback){

    var url = some_link;

    request(url, function (error, response, body) {
        if (error || response.statusCode != 200) {
          // pass error to callback and you may simply return without additional code block below
          console.error('Error in request', error);
          return callback(error, null); 
        } 

        // code executes here if no errors are present

        // for more information, consider using console.log(request); or console.log(body);

        // remember to place error as the first parameter in callback functions 

        callback(null, body);
    });

};

Answer 2

Ensure to utilize the first function callback parameters for handling errors, as this is a default practice in the core of node.js and can be beneficial for your project functions.

Following @ShanSan's advice, make use of console.log, console.error, or console.trace for debugging purposes.

For instance:

var request = require('request'); //using npm package "request"

exports.FooB = function(error, data){ /*operations on data go here*/ };

exports.FooA = function(callback){

    var url = some_link;

    request(url, function (error, response, body) {
        if (error || response.statusCode != 200) {
          // pass error to callback and you may simply return without additional code block below
          console.error('Error in request', error);
          return callback(error, null); 
        } 

        // code executes here if no errors are present

        // for more information, consider using console.log(request); or console.log(body);

        // remember to place error as the first parameter in callback functions 

        callback(null, body);
    });

};

Using a module's internal function as a callback in the "request" operation

Answer №1

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