Create an Express application featuring a pair of API routes, each programmed to deliver one of two responses: either an error message or a

Need assistance with a REST API using Express? Let's build an Express application that operates on port 3000 and links to a database. The database should contain a user collection with the following user details:

a) userId - "user1", firstName - "Akshay", lastName - "Kumar", email - "[email protected]"

b) userId - "user2" firstName - "Rajnikanth", lastName - "", email - "[email protected]"

Please note that including the database part is not necessary (provided for context).

The application requires the following APIs: /users - returns JSON of all users in the DB /users/:userId - returns the object of a single user based on the userId passed

To complete this, modify the following files: response.js app.js

Create a fully operational REST API capable of producing two types of responses - a) Error response - {‘isError’:true,'status’: 500,'errorMessage':’Some error message’,successMessage:null} b) Success response - {‘isError’:false,'status’: 200,'errorMessage':null,successMessage:’Some result’}

PLEASE NOTE: app.listen() function will be handled by the system.

I have tried implementing this solution, but encountered logical errors. Unfortunately, I am unable to test the code as it needs to be submitted online with only syntax error feedback from the website compiler.

All JavaScript files are provided below:

app.js

const express = require('express');
const app = express();
const mongoose = require('mongoose');
const UserModel = require('./User.js');

let db = mongoose.connect('mongodb://testuser:<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="98e8f9ebebeff7eafca9aaabd8fceba9aca1aaadaab6f5f4f9fab6fbf7f5">[email protected]</a>:49252/assignment', { useMongoClient: true });
const responseLib = require('./responseLib');

app.get('/users', function(req, res, err) {

    UserModel.find(function(err, result){
         if(err) {
            let apiResponse = response.generateResponse(true, 500, "Some error message", null);
            res.send(apiResponse);
        } else {
            let apiResponse = response.generateResponse(false, 200, "Some result", result);
            res.send(apiResponse);
        }

    });
});

app.get('/users/:userId', function(req, res, err){

     BlogModel.findOne({ 'blogId': req.params.userId }, (err, result) => {

        if (err) {
            let apiResponse = response.generateResponse(true, 500, "Some error message", null);
            res.send(apiResponse);

        }  else {
            let apiResponse = response.generateResponse(false, 200, "Some result", result);
            res.send(apiResponse);
        }
    });
});



module.exports = app;

User.js

// importing mongoose module
// importing mongoose module
const mongoose = require('mongoose')
// import schema 
const Schema = mongoose.Schema;

let userSchema = new Schema(
    {
        userId: {
            type: String,
            unique: true
        },
        firstName: {
            type: String,
            default: ''
        },
        lastName: {
            type: String,
            default: ''
        },
        email: {
            type: String,
            default: ''
        }
    }
)

mongoose.model('User', userSchema);

module.exports = mongoose.model('User', userSchema)

responseLib.js

let generateResponse = (isError,status,errorMessage,successMessage) =>{

let response = {

    isError : isError,
    status : status,
    errorMessage : errorMessage,
    successMessage : successMessage
}
return response

};// end generate response. 

module.exports = {generateResponse:generateResponse}

Answer №1

When working on your routes for /users/:userId, make sure to use UserModel.findOne(). It is unnecessary to declare err in the app.get routes function since it is already declared in the callback function as (err, result)

  app.get('/users', (req, res) => {

    UserModel.find((err, result) => {
        if (err) {
            res.send(err);
        } else if (result == undefined || result == null || result == '') {
            res.send("No User Data Found");
        } else {
            res.send(result);
        }
    });
 });

 app.get('/users/:userId', (req, res) => {
    UserModel.findOne({ 'userId': req.params.userId }, (err, result) => {
        if (err) {
            res.send(err);
        } else if (result == undefined || result == null || result == '') {
            res.send("No Such User Found");
        } else {
            res.send(result);
        }
    });
 });`

Answer №2

Understanding the issue at hand can be a bit challenging without knowing the exact nature of the "logical error." However, it is possible that the problem lies in failing to set the Status in the HTTP response. Within a HTTP response, both Headers and Body play crucial roles, with the generated response forming the body. Oftentimes, novice developers overlook setting the Status in the Headers.

To rectify this, it is imperative to utilize res.status(200) or res.status(500) to establish the status in the header. This particular step should precede the execution of res.send, as the latter is responsible for sending out the response. By utilizing res.status, you are essentially preparing your response prior to transmission.

For further insights, feel free to consult the comprehensive documentation here.

Answer №3

Here is the code snippet for your assignment:

app.js

const express = require('express');
const app = express();
const mongoose = require('mongoose');
const UserModel = require('./User.js');

let db = mongoose.connect('mongodb://testuser:<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="6f1f0e1c1c18001d0b5e5d5c2f0b1c5e5b565d5a5d4102030e0d410c0002">[email protected]</a>:49252/assignment', { useMongoClient: true });
const response = require('./responseLib');
app.get('/users', (req, res) => {

    UserModel.find((err, result) => {
        if (err) {
            let apiResponse = response.generateResponse(true, 500, "Some error message", null);
            res.send(apiResponse);
        } else if (result ===undefined || result ===null || result ==='') {
            let apiResponse = response.generateResponse(true, 500, "Some error message", null);
            res.send(apiResponse);
        } else {
             let apiResponse = response.generateResponse(false, 200, null, 'Some result');
            res.send(apiResponse);
        }
    });
 });

 app.get('/users/:userId', (req, res) => {
    UserModel.findOne({ 'userId': req.params.userId }, (err, result) => {
        if (err) {
            let apiResponse = response.generateResponse(true, 500, "Some error message", null);
            res.send(apiResponse);
        } else if (result ===undefined || result ===null || result ==='') {
           let apiResponse = response.generateResponse(true, 500, "Some error message", null);
            res.send(apiResponse);
        } else {
             let apiResponse = response.generateResponse(false, 200, null, 'Some result');
            res.send(apiResponse);
        }
    });
 });



module.exports = app;

responseLib.js

let generateResponse = (isError,status,errorMessage,successMessage) =>{
   let response = {

    isError : isError,
    status : status,
    errorMessage : errorMessage,
    successMessage : successMessage
};
return response; 


};// end generate response. 

module.exports = {generateResponse:generateResponse};

user.js

// importing mongoose module
const mongoose = require('mongoose');
// import schema 
const Schema = mongoose.Schema;

let userSchema = new Schema(
    {
        userId: {
            type: String,
            unique: true
        },
        firstName: {
            type: String,
            default: ''
        },
        lastName: {
            type: String,
            default: ''
        },
        email: {
            type: String,
            default: ''
        }
    }
);
mongoose.model('User', userSchema);

module.exports = mongoose.model('User', userSchema);

Use this code snippet for your assignment.

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