Using Promises, async / await with MongoDB

Using Promises, async / await with MongoDB

Using Promises, async / await with MongoDB . How to handle API requests with a chain of MongoDB queries

You are writing a backend service for your web app and you need to fetch data from your mongo cluster. The problem is, you do not want your request to be returned in a synchronous manor — instead I want mongo queries to be carried out, get the returned result, handle it and return the JSON to my front end when it is ready.

You want to conform to ES6/7 javascript standards to maintain your app code and stay relevant; you need to implement promises, async and await functionality, wrapped around your db.collection mongo requests.

Breaking down the process

Before the full example and explanation of a fully-fledged asynchronous API request, I want to briefly revisit promises and using async/await in javascript.

Promise

Promises give us a way to handle asynchronous processing in a more synchronous fashion. They represent a value that we can handle at some point in the future; it will eventually be returned, or resolved.

If we call a promise and console.log it, we will be greeted with a pending promise. The promise has not yet been resolved. It is in the middle of completing what we code it to do. When it has resolved we will be able to retreive the data we originally intended the promise to return to us.

Promises are immutable, the handler cannot be changed. We are also guaranteed to receive a return value: either what we intended or an error.

We will write our promises inside ES6 functions, and then asynchronously call it using await and async.

What does a promise look like? Something like this:

var myPromise = () => (
    new Promise((resolve, reject) => {
        
        //do something, fetch something....
        //you guessed it, mongo queries go here.
        db.collection('your_collection').find(...)
        //I can continue to process my result inside my promise
        .then(function(result){
            //another query can be called based on my result...
            return updatedResult;
        })
         //This promise may take a while...
         .then(function(result){
             //post processing, non related mongo code...
             //when you are ready, you can resolve the promise.
             resolve(result);
        });
    })
);

Notice the second handler (typically named reject). It is a function to call to reject the promise if it can't resolve the future value.

We could expand the previous psuedocode to account for rejecting unwanted data:

//when you are ready you can resolve the promise.
var somethingWentWrong = (dataReturned == null);
(somethingWentWrong)
   ? reject('something messed up') 
   : resolve(result);

Now let’s move onto asynchronously processing our promises.

async / await

As you can see, the async and await keywords are absent from our Promise code. We use them to configure asynchronous functions that call our promise and wait for it to complete, like this:

var callMyPromise = async () => {
    var result = await (myPromise());
    return result;
};

See how simple that was? Some articles online make the process look rather complicated. It is not — separate your promise declarations and your asynchronous functions. Make things simple to read and build upon; your team will appreciate it.

So the last piece of the puzzle is to coherently put everything together so we can finally return our API request, which looks something like this:

callMyPromise().then(function(result) {
    //close mongo client
    client.close();
    //feel free to process your final result before sending
    //it back to your front end
    //return the API request
    res.json(result);
});

Putting everything together

Let’s put everything we just went through together to create a full API request. Let’s say I am using Express as my backend service:

router.post('/api/get_data', (req, res, next) => {
   try {
      MongoClient.connect(connectionStr, mongoOptions, function(err, client) {
       assert.equal(null, err);
       const db = client.db('db');
      
       //Step 1: declare promise
      
       var myPromise = () => {
         return new Promise((resolve, reject) => {
        
            db
             .collection('your_collection')
             .find({id: 123})
             .limit(1)
             .toArray(function(err, data) {
                 err 
                    ? reject(err) 
                    : resolve(data[0]);
               });
         });
       };

       //Step 2: async promise handler
       var callMyPromise = async () => {
          
          var result = await (myPromise());
          //anything here is executed after result is resolved
          return result;
       };
 
       //Step 3: make the call
       callMyPromise().then(function(result) {
          client.close();
          res.json(result);
       });
    }); //end mongo client
   
   } catch (e) {
     next(e)
   }
});
module.exports = router;

Some points about this example:

  • The entire process is wrapped in a try catch so I can handle any errors that occur.
  • res.json returns the result of my data as a JSON object.

Now, what we have done here is mix _async_ and _await_ features with our _then()_ callback functions. However we could choose to utilise only one of these.

So why did we use both in the example above? Because it demonstrated how we can await an async function to resolve, which are also treated as promises.

Let’s explore how we can optimise the example below.

Using promises without async / await

Now, we could in fact remove the async / await keywords here along with step 2, and simply continue with a then() block after the promise is called:

//Step 1: declare promise
var myPromise = () => {
   ...
};

//omitting step 2

//step 3: make the call
myPromise().then(res => {
   client.close();
   res.json(result);
};

Indeed, this is cleaner syntax. In reality, your promise will be imported from an external modules file, therefore step 3 will be the only code present at your routes level.

Using async / await only

So why would we use the async / await keywords in this example?

Check out the rewritten example below.

We declare our promise as step 1 like before, but we then utilise await to pause execution until myPromise is resolved, before closing the mongo client and resolving the API call.

Notice the async keyword is now being used in the router callback function on the first line:

router.post('/api/get_data', async (req, res, next) => {
try {
MongoClient.connect(connectionStr, mongoOptions, function(err, client) {
   assert.equal(null, err);
   const db = client.db('db');
      
   //Step 1: declare promise
      
    var myPromise = () => {
       return new Promise((resolve, reject) => {
        
          db
          .collection('your_collection')
          .find({id: 123})
          .limit(1)
          .toArray(function(err, data) {
             err 
                ? reject(err) 
                : resolve(data[0]);
           });
       });
    };
   //await myPromise
   var result = await myPromise();
   //continue execution
   client.close();
   res.json(result);
}); //end mongo client
} catch (e) {
   next(e)
}
});
module.exports = router;

Which style do you prefer? then() may appear more readable for some, whereas await may look cleaner more minimal code for the more experienced programmer.

Ready to Continue?

I continue exploring the promises, async and await concepts in follow-on articles, that expands on the concepts in this article, to creating a library of promise based exports for your API calls.

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How to Use Express.js, Node.js and MongoDB.js

How to Use Express.js, Node.js and MongoDB.js

In this post, I will show you how to use Express.js, Node.js and MongoDB.js. We will be creating a very simple Node application, that will allow users to input data that they want to store in a MongoDB database. It will also show all items that have been entered into the database.

In this post, I will show you how to use Express.js, Node.js and MongoDB.js. We will be creating a very simple Node application, that will allow users to input data that they want to store in a MongoDB database. It will also show all items that have been entered into the database.

Creating a Node Application

To get started I would recommend creating a new database that will contain our application. For this demo I am creating a directory called node-demo. After creating the directory you will need to change into that directory.

mkdir node-demo
cd node-demo

Once we are in the directory we will need to create an application and we can do this by running the command
npm init

This will ask you a series of questions. Here are the answers I gave to the prompts.

The first step is to create a file that will contain our code for our Node.js server.

touch app.js

In our app.js we are going to add the following code to build a very simple Node.js Application.

var express = require("express");
var app = express();
var port = 3000;
 
app.get("/", (req, res) => {
  res.send("Hello World");
});
 
app.listen(port, () => {
  console.log("Server listening on port " + port);
});

What the code does is require the express.js application. It then creates app by calling express. We define our port to be 3000.

The app.use line will listen to requests from the browser and will return the text “Hello World” back to the browser.

The last line actually starts the server and tells it to listen on port 3000.

Installing Express

Our app.js required the Express.js module. We need to install express in order for this to work properly. Go to your terminal and enter this command.

npm install express --save

This command will install the express module into our package.json. The module is installed as a dependency in our package.json as shown below.

To test our application you can go to the terminal and enter the command

node app.js

Open up a browser and navigate to the url http://localhost:3000

You will see the following in your browser

Creating Website to Save Data to MongoDB Database

Instead of showing the text “Hello World” when people view your application, what we want to do is to show a place for user to save data to the database.

We are going to allow users to enter a first name and a last name that we will be saving in the database.

To do this we will need to create a basic HTML file. In your terminal enter the following command to create an index.html file.

touch index.html

In our index.html file we will be creating an input filed where users can input data that they want to have stored in the database. We will also need a button for users to click on that will add the data to the database.

Here is what our index.html file looks like.

<!DOCTYPE html>
<html>
  <head>
    <title>Intro to Node and MongoDB<title>
  <head>

  <body>
    <h1>Into to Node and MongoDB<&#47;h1>
    <form method="post" action="/addname">
      <label>Enter Your Name<&#47;label><br>
      <input type="text" name="firstName" placeholder="Enter first name..." required>
      <input type="text" name="lastName" placeholder="Enter last name..." required>
      <input type="submit" value="Add Name">
    </form>
  <body>
<html>

If you are familiar with HTML, you will not find anything unusual in our code for our index.html file. We are creating a form where users can input their first name and last name and then click an “Add Name” button.

The form will do a post call to the /addname endpoint. We will be talking about endpoints and post later in this tutorial.

Displaying our Website to Users

We were previously displaying the text “Hello World” to users when they visited our website. Now we want to display our html file that we created. To do this we will need to change the app.use line our our app.js file.

We will be using the sendFile command to show the index.html file. We will need to tell the server exactly where to find the index.html file. We can do that by using a node global call __dirname. The __dirname will provide the current directly where the command was run. We will then append the path to our index.html file.

The app.use lines will need to be changed to
app.use("/", (req, res) => {   res.sendFile(__dirname + "/index.html"); });

Once you have saved your app.js file, we can test it by going to terminal and running node app.js

Open your browser and navigate to “http://localhost:3000”. You will see the following

Connecting to the Database

Now we need to add our database to the application. We will be connecting to a MongoDB database. I am assuming that you already have MongoDB installed and running on your computer.

To connect to the MongoDB database we are going to use a module called Mongoose. We will need to install mongoose module just like we did with express. Go to your terminal and enter the following command.
npm install mongoose --save

This will install the mongoose model and add it as a dependency in our package.json.

Connecting to the Database

Now that we have the mongoose module installed, we need to connect to the database in our app.js file. MongoDB, by default, runs on port 27017. You connect to the database by telling it the location of the database and the name of the database.

In our app.js file after the line for the port and before the app.use line, enter the following two lines to get access to mongoose and to connect to the database. For the database, I am going to use “node-demo”.

var mongoose = require("mongoose"); mongoose.Promise = global.Promise; mongoose.connect("mongodb://localhost:27017/node-demo");

Creating a Database Schema

Once the user enters data in the input field and clicks the add button, we want the contents of the input field to be stored in the database. In order to know the format of the data in the database, we need to have a Schema.

For this tutorial, we will need a very simple Schema that has only two fields. I am going to call the field firstName and lastName. The data stored in both fields will be a String.

After connecting to the database in our app.js we need to define our Schema. Here are the lines you need to add to the app.js.
var nameSchema = new mongoose.Schema({   firstName: String,   lastNameName: String });

Once we have built our Schema, we need to create a model from it. I am going to call my model “DataInput”. Here is the line you will add next to create our mode.
var User = mongoose.model("User", nameSchema);

Creating RESTful API

Now that we have a connection to our database, we need to create the mechanism by which data will be added to the database. This is done through our REST API. We will need to create an endpoint that will be used to send data to our server. Once the server receives this data then it will store the data in the database.

An endpoint is a route that our server will be listening to to get data from the browser. We already have one route that we have created already in the application and that is the route that is listening at the endpoint “/” which is the homepage of our application.

HTTP Verbs in a REST API

The communication between the client(the browser) and the server is done through an HTTP verb. The most common HTTP verbs are
GET, PUT, POST, and DELETE.

The following table explains what each HTTP verb does.

HTTP Verb Operation
GET Read
POST Create
PUT Update
DELETE Delete

As you can see from these verbs, they form the basis of CRUD operations that I talked about previously.

Building a CRUD endpoint

If you remember, the form in our index.html file used a post method to call this endpoint. We will now create this endpoint.

In our previous endpoint we used a “GET” http verb to display the index.html file. We are going to do something very similar but instead of using “GET”, we are going to use “POST”. To get started this is what the framework of our endpoint will look like.

app.post("/addname", (req, res) => {
 
});
Express Middleware

To fill out the contents of our endpoint, we want to store the firstName and lastName entered by the user into the database. The values for firstName and lastName are in the body of the request that we send to the server. We want to capture that data, convert it to JSON and store it into the database.

Express.js version 4 removed all middleware. To parse the data in the body we will need to add middleware into our application to provide this functionality. We will be using the body-parser module. We need to install it, so in your terminal window enter the following command.

npm install body-parser --save

Once it is installed, we will need to require this module and configure it. The configuration will allow us to pass the data for firstName and lastName in the body to the server. It can also convert that data into JSON format. This will be handy because we can take this formatted data and save it directly into our database.

To add the body-parser middleware to our application and configure it, we can add the following lines directly after the line that sets our port.

var bodyParser = require('body-parser');
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));
Saving data to database

Mongoose provides a save function that will take a JSON object and store it in the database. Our body-parser middleware, will convert the user’s input into the JSON format for us.

To save the data into the database, we need to create a new instance of our model that we created early. We will pass into this instance the user’s input. Once we have it then we just need to enter the command “save”.

Mongoose will return a promise on a save to the database. A promise is what is returned when the save to the database completes. This save will either finish successfully or it will fail. A promise provides two methods that will handle both of these scenarios.

If this save to the database was successful it will return to the .then segment of the promise. In this case we want to send text back the user to let them know the data was saved to the database.

If it fails it will return to the .catch segment of the promise. In this case, we want to send text back to the user telling them the data was not saved to the database. It is best practice to also change the statusCode that is returned from the default 200 to a 400. A 400 statusCode signifies that the operation failed.

Now putting all of this together here is what our final endpoint will look like.

app.post("/addname", (req, res) => {
  var myData = new User(req.body);
  myData.save()
    .then(item => {
      res.send("item saved to database");
    })
    .catch(err => {
      res.status(400).send("unable to save to database");
    });
});
Testing our code

Save your code. Go to your terminal and enter the command node app.js to start our server. Open up your browser and navigate to the URL “http://localhost:3000”. You will see our index.html file displayed to you.

Make sure you have mongo running.

Enter your first name and last name in the input fields and then click the “Add Name” button. You should get back text that says the name has been saved to the database like below.

Access to Code

The final version of the code is available in my Github repo. To access the code click here. Thank you for reading !

Node.js, ExpressJs, MongoDB and Vue.js (MEVN Stack) Application Tutorial

Node.js, ExpressJs, MongoDB and Vue.js (MEVN Stack) Application Tutorial

In this tutorial, you'll learn how to integrate Vue.js with Node.js backend (using Express framework) and MongoDB and how to build application with Node.js, ExpressJs, MongoDB and Vue.js

In this tutorial, you'll learn how to integrate Vue.js with Node.js backend (using Express framework) and MongoDB and how to build application with Node.js, ExpressJs, MongoDB and Vue.js

Vue.js is a JavaScript framework with growing number of users. Released 4 years ago, it’s now one of the most populare front-end frameworks. There are some reasons why people like Vue.js. Using Vue.js is very simple if you are already familiar with HTML and JavaScript. They also provide clear documentation and examples, makes it easy for starters to learn the framework. Vue.js can be used for both simple and complex applications. If your application is quite complex, you can use Vuex for state management, which is officially supported. In addition, it’s also very flexible that yu can write template in HTML, JavaScript or JSX.

This tutorial shows you how to integrate Vue.js with Node.js backend (using Express framework) and MongoDB. As for example, we’re going to create a simple application for managing posts which includes list posts, create post, update post and delete post (basic CRUD functionality). I divide this tutorial into two parts. The first part is setting up the Node.js back-end and database. The other part is writing Vue.js code including how to build .vue code using Webpack.

Dependencies

There are some dependencies required for this project. Add the dependencies below to your package.json. Then run npm install to install these dependencies.

  "dependencies": {
    "body-parser": "~1.17.2",
    "dotenv": "~4.0.0",
    "express": "~4.16.3",
    "lodash": "~4.17.10",
    "mongoose": "~5.2.9",
    "morgan": "~1.9.0"
  },
  "devDependencies": {
    "axios": "~0.18.0",
    "babel-core": "~6.26.3",
    "babel-loader": "~7.1.5",
    "babel-preset-env": "~1.7.0",
    "babel-preset-stage-3": "~6.24.1",
    "bootstrap-vue": "~2.0.0-rc.11",
    "cross-env": "~5.2.0",
    "css-loader": "~1.0.0",
    "vue": "~2.5.17",
    "vue-loader": "~15.3.0",
    "vue-router": "~3.0.1",
    "vue-style-loader": "~4.1.2",
    "vue-template-compiler": "~2.5.17",
    "webpack": "~4.16.5",
    "webpack-cli": "^3.1.0"
  },

Project Structure

Below is the overview of directory structure for this project.

  app
    config
    controllers
    models
    queries
    routes
    views
  public
    dist
    src

The app directory contains all files related to server-side. The public directory contains two sub-directories: dist and src. dist is used for the output of build result, while src is for front-end code files.

Model

First, we define a model for Post using Mongoose. To make it simple, it only has two properties: title and content.

app/models/Post.js

  const mongoose = require('mongoose');

  const { Schema } = mongoose;

  const PostSchema = new Schema(
    {
      title: { type: String, trim: true, index: true, default: '' },
      content: { type: String },
    },
    {
      collection: 'posts',
      timestamps: true,
    },
  );

  module.exports = mongoose.model('Post', PostSchema);

Queries

After defining the model, we write some queries that will be needed in the controllers.

app/queries/posts.js

  const Post = require('../models/Post');

  /**
   * Save a post.
   *
   * @param {Object} post - Javascript object or Mongoose object
   * @returns {Promise.}
   */
  exports.save = (post) => {
    if (!(post instanceof Post)) {
      post = new Post(post);
    }

    return post.save();
  };

  /**
   * Get post list.
   * @param {object} [criteria] - Filter options
   * @returns {Promise.<Array.>}
   */
  exports.getPostList = (criteria = {}) => Post.find(criteria);

  /**
   * Get post by ID.
   * @param {string} id - Post ID
   * @returns {Promise.}
   */
  exports.getPostById = id => Post.findOne({ _id: id });

  /**
   * Delete a post.
   * @param {string} id - Post ID
   * @returns {Promise}
   */
  exports.deletePost = id => Post.findByIdAndRemove(id);

Controllers

We need API controllers for handling create post, get post listing, get detail of a post, update a post and delete a post.

app/controllers/api/posts/create.js

  const postQueries = require('../../../queries/posts');

  module.exports = (req, res) => postQueries.save(req.body)
    .then((post) => {
      if (!post) {
        return Promise.reject(new Error('Post not created'));
      }

      return res.status(200).send(post);
    })
    .catch((err) => {
      console.error(err);

      return res.status(500).send('Unable to create post');
    });

app/controllers/api/posts/delete.js

  const postQueries = require('../../../queries/posts');

  module.exports = (req, res) => postQueries.deletePost(req.params.id)
    .then(() => res.status(200).send())
    .catch((err) => {
      console.error(err);

      return res.status(500).send('Unable to delete post');
    });

app/controllers/api/posts/details.js

  const postQueries = require('../../../queries/posts');

  module.exports = (req, res) => postQueries.getPostById(req.params.id)
    .then((post) => {
      if (!post) {
        return Promise.reject(new Error('Post not found'));
      }

      return res.status(200).send(post);
    })
    .catch((err) => {
      console.error(err);

      return res.status(500).send('Unable to get post');
    });

app/controllers/api/posts/list.js

  const postQueries = require('../../../queries/posts');

  module.exports = (req, res) => postQueries.getPostList(req.params.id)
    .then(posts => res.status(200).send(posts))
    .catch((err) => {
      console.error(err);

      return res.status(500).send('Unable to get post list');
    });

app/controllers/api/posts/update.js

  const _ = require('lodash');

  const postQueries = require('../../../queries/posts');

  module.exports = (req, res) => postQueries.getPostById(req.params.id)
    .then(async (post) => {
      if (!post) {
        return Promise.reject(new Error('Post not found'));
      }

      const { title, content } = req.body;

      _.assign(post, {
        title, content
      });

      await postQueries.save(post);

      return res.status(200).send({
        success: true,
        data: post,
      })
    })
    .catch((err) => {
      console.error(err);

      return res.status(500).send('Unable to update post');
    });

Routes

We need to have some pages for user interaction and some API endpoints for processing HTTP requests. To make the app scalable, it’s better to separate the routes for pages and APIs.

app/routes/index.js

  const express = require('express');

  const routes = express.Router();

  routes.use('/api', require('./api'));
  routes.use('/', require('./pages'));

  module.exports = routes;


Below is the API routes.

app/routes/api/index.js

  const express = require('express');

  const router = express.Router();

  router.get('/posts/', require('../../controllers/api/posts/list'));
  router.get('/posts/:id', require('../../controllers/api/posts/details'));
  router.post('/posts/', require('../../controllers/api/posts/create'));
  router.patch('/posts/:id', require('../../controllers/api/posts/update'));
  router.delete('/posts/:id', require('../../controllers/api/posts/delete'));

  module.exports = router;


For the pages, in this tutorial, we use plain HTML file. You can easily replace it with any HTML template engine if you want. The HTML file contains a div whose id is app. Later, in Vue.js application, it will use the element with id app for rendering the content. What will be rendered on each pages is configured on Vue.js route on part 2 of this tutorial.

app/routes/pages/index.js

  const express = require('express');

  const router = express.Router();

  router.get('/posts/', (req, res) => {
    res.sendFile(`${__basedir}/views/index.html`);
  });

  router.get('/posts/create', (req, res) => {
    res.sendFile(`${__basedir}/views/index.html`);
  });

  router.get('/posts/:id', (req, res) => {
    res.sendFile(`${__basedir}/views/index.html`);
  });

  module.exports = router;

Below is the HTML file

app/views/index.html

  <!DOCTYPE html>
  <html>
    <head>
      <meta charset="utf-8">
      <title>VueJS Tutorial by Woolha.com</title>
      <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.4.0/css/font-awesome.min.css" type="text/css" media="all" />
      <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
      <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
    </head>
    <body>
      <div id="app"></div>
      <script src="/dist/js/main.js"></script>
    </body>
  </html>

Below is the main script of the application, you need to run this for starting the server-side application.

app/index.js

  require('dotenv').config();

  const bodyParser = require('body-parser');
  const express = require('express');
  const http = require('http');
  const mongoose = require('mongoose');
  const morgan = require('morgan');
  const path = require('path');

  const dbConfig = require('./config/database');
  const routes = require('./routes');

  const app = express();
  const port = process.env.PORT || 4000;

  global.__basedir = __dirname;

  mongoose.Promise = global.Promise;

  mongoose.connect(dbConfig.url, dbConfig.options, (err) => {
    if (err) {
      console.error(err.stack || err);
    }
  });

  /* General setup */
  app.use(morgan('dev'));
  app.use(bodyParser.json());
  app.use(bodyParser.urlencoded({ extended: true }));
  app.use(morgan('dev'));

  app.use('/', routes);

  const MAX_AGE = 86400000;

  // Select which directories or files under public can be served to users
  app.use('/', express.static(path.join(__dirname, '../public'), { maxAge: MAX_AGE }));

  // Error handler
  app.use((err, req, res, next) => { // eslint-disable-line no-unused-vars
    res.status(err.status || 500);

    if (err.status === 404) {
      res.locals.page = {
        title: 'Not Found',
        noIndex: true,
      };

      console.error(`Not found: ${req.url}`);

      return res.status(404).send();
    }

    console.error(err.stack || err);

    return res.status(500).send();
  });

  http
    .createServer(app)
    .listen(port, () => {
      console.info(`HTTP server started on port ${port}`);
    })
    .on('error', (err) => {
      console.error(err.stack || err);
    });

  process.on('uncaughtException', (err) => {
    if (err.name === 'MongoError') {
      mongoose.connection.emit('error', err);
    } else {
      console.error(err.stack || err);
    }
  });

  module.exports = app;

That’s all for the server side preparation. On the next part, we’re going to set up the Vue.js client-side application and build the code into a single JavaScript file ready to be loaded from HTML.

Then, we build the code using Webpack, so that it can be loaded from HTML. In this tutorial, we’re building a simple application with basic CRUD functionality for managing posts.

Create Vue.js Components

For managing posts, there are three components we’re going to create. The first one is for creating a new post. The second is for editing a post. The other is for managing posts (displaying list of posts and allow post deletion)

First, this is the component for creating a new post. It has one method createPost which validate data and send HTTP request to the server. We use axios for sending HTTP request.

public/src/components/Posts/Create.vue

  <template>
    <b-container>
      <h1 class="d-flex justify-content-center">Create a Post</h1>
      <p v-if="errors.length">
        <b>Please correct the following error(s):</b>
        <ul>
          <li v-for="error in errors">{{ error }}</li>
        </ul>
      </p>
      <b-form @submit.prevent>
        <b-form-group>
          <b-form-input type="text" class="form-control" placeholder="Title of the post" v-model="post.title"></b-form-input>
        </b-form-group>
        <b-form-group>
          <b-form-textarea class="form-control" placeholder="Write the content here" v-model="post.content"></b-form-textarea>
        </b-form-group>
        <b-button variant="primary" v-on:click="createPost">Create Post</b-button>
      </b-form>
    </b-container>
  </template>

  <script>
    import axios from 'axios';

    export default {
      data: () => ({
        errors: [],
        post: {
          title: '',
          content: '',
        },
      }),
      methods: {
        createPost(event) {
          if (event) {
            event.preventDefault();
          }

          if (!this.post.title) {
            this.errors = [];

            if (!this.post.title) {
              this.errors.push('Title required.');
            }

            return;
          }

          const url = 'http://localhost:4000/api/posts';
          const param = this.post;

          axios
            .post(url, param)
            .then((response) => {
              console.log(response);
              window.location.href = 'http://localhost:4000/posts';
            }).catch((error) => {
              console.log(error);
            });
        },
      }
    }
  </script>


Below is the component for editing a post. Of course, we need the current data of the post before editing it. Therefore, there’s fetchPost method called when the component is created. There’s also updatePost method which validate data and call the API for updating post.

public/src/components/Posts/Edit.vue

  <template>
    <b-container>
      <h1 class="d-flex justify-content-center">Edit a Post</h1>
      <p v-if="errors.length">
        <b>Please correct the following error(s):</b>
        <ul>
          <li v-for="error in errors">{{ error }}</li>
        </ul>
      </p>
      <b-form @submit.prevent>
        <b-form-group>
          <b-form-input type="text" class="form-control" placeholder="Title of the post" v-model="post.title"></b-form-input>
        </b-form-group>
        <b-form-group>
          <b-form-textarea class="form-control" placeholder="Write the content here" v-model="post.content"></b-form-textarea>
        </b-form-group>
        <b-button variant="primary" v-on:click="updatePost">Update Post</b-button>
      </b-form>
    </b-container>
  </template>

  <script>
    import axios from 'axios';

    export default {
      data: () => ({
        errors: [],
        post: {
          _id: '',
          title: '',
          content: '',
        },
      }),
      created: function() {
        this.fetchPost();
      },
      methods: {
        fetchPost() {
          const postId = this.$route.params.id;
          const url = `http://localhost:4000/api/posts/${postId}`;

          axios
            .get(url)
            .then((response) => {
              this.post = response.data;
              console.log('this.post;');
              console.log(this.post);
          });
        },
        updatePost(event) {
          if (event) {
            event.preventDefault();
          }

          if (!this.post.title) {
            this.errors = [];

            if (!this.post.title) {
              this.errors.push('Title required.');
            }

            return;
          }

          const url = `http://localhost:4000/api/posts/${this.post._id}`;
          const param = this.post;

          axios
            .patch(url, param)
            .then((response) => {
                console.log(response);
              window.alert('Post successfully saved');
            }).catch((error) => {
              console.log(error);
            });
        },
      }
    }
  </script>


For managing posts, we need to fetch the list of post first. Similar to the edit component, in this component, we have fetchPosts method called when the component is created. For deleting a post, there’s also a method deletePost. If post successfully deleted, the fetchPosts method is called again to refresh the post list.

public/src/components/Posts/List.vue

  <template>
    <b-container>
      <h1 class="d-flex justify-content-center">Post List</h1>
      <b-button variant="primary" style="color: #ffffff; margin: 20px;"><a href="/posts/create" style="color: #ffffff;">Create New Post</a></b-button>
      <b-container-fluid v-if="posts.length">
        <table class="table">
          <thead>
            <tr class="d-flex">
              <td class="col-8">Titleqqqqqqqqq</td>
              <td class="col-4">Actions</td>
            </tr>
          </thead>
          <tbody>
            <tr v-for="post in posts" class="d-flex">
              <td class="col-8">{{ post.title }}</td>
              <td class="col-2"><a v-bind:href="'http://localhost:4000/posts/' + post._id"><button type="button" class="btn btn-primary"><i class="fa fa-edit" aria-hidden="true"></i></button></a></td>
              <td class="col-2"><button type="button" class="btn btn-danger" v-on:click="deletePost(post._id)"><i class="fa fa-remove" aria-hidden="true"></i></button></td>
            </tr>
          </tbody>
        </table>
      </b-container-fluid>
    </b-container>
  </template>

  <script>
    import axios from 'axios';

    export default {
      data: () => ({
        posts: [],
      }),
      created: () => {
        this.fetchPosts();
      },
      methods: {
        fetchPosts() {
          const url = 'http://localhost:4000/api/posts/';

          axios
            .get(url)
            .then((response) => {
              console.log(response.data);
              this.posts = response.data;
          });
        },
        deletePost(id) {
          if (event) {
            event.preventDefault();
          }

          const url = `http://localhost:4000/api/posts/${id}`;
          const param = this.post;

          axios
            .delete(url, param)
            .then((response) => {
              console.log(response);
              console.log('Post successfully deleted');

              this.fetchPosts();
            }).catch((error) => {
              console.log(error);
            });
        },
      }
    }
  </script>


All of the components above are wrapped into a root component which roles as the basic template. The root component renders the navbar which is same across all components. The component for each routes will be rendered on router-view.

public/src/App.vue

  <template>
    <div>
      <b-navbar toggleable="md" type="dark" variant="dark">
        <b-navbar-toggle target="nav_collapse"></b-navbar-toggle>
        <b-navbar-brand to="/">My Vue App</b-navbar-brand>
        <b-collapse is-nav id="nav_collapse">
          <b-navbar-nav>
            <b-nav-item to="/">Home</b-nav-item>
            <b-nav-item to="/posts">Manage Posts</b-nav-item>
          </b-navbar-nav>
        </b-collapse>
      </b-navbar>
      <!-- routes will be rendered here -->
      <router-view />
    </div>
  </template>

  <script>

  export default {
    name: 'app',
    data () {},
    methods: {}
  }
  </script>


For determining which component should be rendered, we use Vue.js’ router. For each routes, we need to define the path, component name and the component itself. A component will be rendered if the current URL matches the path.

public/src/router/index.js

  import Vue from 'vue'
  import Router from 'vue-router'

  import CreatePost from '../components/Posts/Create.vue';
  import EditPost from '../components/Posts/Edit.vue';
  import ListPost from '../components/Posts/List.vue';

  Vue.use(Router);

  let router = new Router({
    mode: 'history',
    routes: [
      {
        path: '/posts',
        name: 'ListPost',
        component: ListPost,
      },
      {
        path: '/posts/create',
        name: 'CreatePost',
        component: CreatePost,
      },
      {
        path: '/posts/:id',
        name: 'EditPost',
        component: EditPost,
      },
    ]
  });

  export default router;


Lastly, we need a main script as the entry point which imports the main App component and the router. Inside, it creates a new Vue instance

webpack.config.js

  import BootstrapVue from 'bootstrap-vue';
  import Vue from 'vue';

  import App from './App.vue';
  import router from './router';

  Vue.use(BootstrapVue);
  Vue.config.productionTip = false;
  new Vue({
    el: '#app',
    router,
    render: h => h(App),
  });

Configure Webpack

For building the code into a single JavaSript file. Below is the basic configuration for Webpack 4.

webpack.config.js

  const { VueLoaderPlugin } = require('vue-loader');

  module.exports = {
    entry: './public/src/main.js',
    output: {
      path: `${__dirname}/public/dist/js/`,
      filename: '[name].js',
    },
    resolve: {
      modules: [
        'node_modules',
      ],
      alias: {
        // vue: './vue.js'
      }
    },
    module: {
      rules: [
        {
          test: /\.css$/,
          use: [
            'vue-style-loader',
            'css-loader'
          ]
        },
        {
          test: /\.vue$/,
          loader: 'vue-loader',
          options: {
            loaders: {
            }
            // other vue-loader options go here
          }
        },
        {
          test: /\.js$/,
          loader: 'babel-loader',
          exclude: /node_modules/
        },
      ]
    },
    plugins: [
      new VueLoaderPlugin(),
    ]

After that, run ./node_modules/webpack/bin/webpack.js. You can add the command to the scripts section of package.json, so you can run Webpack with a shorter command npm run build, as examplified below.

  "dependencies": {
    ...
  },
  "devDependencies": {
    ...
  },
  "scripts": {
    "build": "./node_modules/webpack/bin/webpack.js",
    "start": "node app/index.js"
  },

Finally, you can start to try the application. This code is also available on Woolha.com’s Github.

Build a REST API using Node.js, Express.js, Mongoose.js and MongoDB

Build a REST API using Node.js, Express.js, Mongoose.js and MongoDB

Node.js, Express.js, Mongoose.js, and MongoDB is a great combination for building easy and fast REST API. You will see how fast that combination than other existing frameworks because of Node.js is a packaged compilation of Google’s V8 JavaScript engine and it works on non-blocking and event-driven I/O. Express.js is a Javascript web server that has a complete function of web development including REST API.

Node.js, Express.js, Mongoose.js, and MongoDB is a great combination for building easy and fast REST API. You will see how fast that combination than other existing frameworks because of Node.js is a packaged compilation of Google’s V8 JavaScript engine and it works on non-blocking and event-driven I/O. Express.js is a Javascript web server that has a complete function of web development including REST API.

This tutorial divided into several steps:

Step #1. Create Express.js Application and Install Required Modules
Step #2. Add Mongoose.js Module as ORM for MongoDB
Step #3. Create Product Mongoose Model
Step #4. Create Routes for the REST API endpoint
Step #5. Test REST API Endpoints

Source codes here:
https://github.com/didinj/NodeRestApi...