Mongoose - Creating an Application

So lets create a project folder “node-mongoose” and inside your project folder create a folder called models and inside that create a file called todos.js and paste below code into it and your todos.js model file should look like this:

// models/todos.js


const mongoose = require("mongoose");
const Schema = mongoose.Schema;

const todoSchema = new Schema(
  {
    description: {
      type: String,
      required: [true, "please enter task details"],
    },
    completed: {
      type: Boolean,
      default: false,
    },
  },
  {
    timestamps: true,
  }
);

var Todos = mongoose.model("Todo", todoSchema);

module.exports = Todos;

In previous section we had implemented this model, if you haven't followed that checkout this, then you are good to continue this section.

Folder Structure:

node-mongoose
  - models
     - todos.js

Now, open a terminal in node-mongoose i.e root folder of your project and follow below steps:-

1. npm init -y
2. Create a file called app.js
3. Install express using npm install express
4. Install mongoose using npm install mongoose
5. Install dotenv using npm install dotenv
6. Create a file called app.js in root folder of your project
7. Now follow the steps in this blog and get the database url which will look like this :
   • mongodb+srv://sample_user:<password>@my-sample-cluster-b3ugy.mongodb.net/<dbname>?retryWrites=true&w=majority
8. Create a .env file in the root folder
9. Add this line in the .env file with your password and database name DATABASE_URL=mongodb+srv://sample_user:<password>@my-sample-cluster-b3ugy.mongodb.net/<dbname>?retryWrites=true&w=majority
10. Also to ensure your database connection should not visible to other if you are storing your code on a service like Github. Create a .gitignore file and enter the file name .env inside it. So git will not keep track of this file.
11. Also add one more variable on new line inside .env file called PORT=3000

Your .env file should look like:

DATABASE_URL=mongodb+srv://sample_user:<password>@my-sample-cluster-b3ugy.mongodb.net/<dbname>?retryWrites=true&w=majority
PORT=3000

Your .gitignore file should look like

node_modules
.env

Now, lets import the packages we have install into the app.js file

const express = require("express");
const mongoose = require("mongoose");
const dotenv = require("dotenv");

Now, lets load the environment variable

dotenv.config({ path: ".env" });
const PORT = process.env.PORT;
const dbURI = process.env.DATABASE_URL;

Now lets import the model todos we have created inside the models/ folder

//model
const Tasks = require("./models/todos");

now , lets create a database connection:
 

const connect = mongoose.connect(dbURI, {
  useNewUrlParser: true,
  useUnifiedTopology: true,
});

connect.then(
  (db) => {
    console.log("Connected Successfully to Mongodb Server");

  },
  (err) => {
    console.log(err);
  }
);

Lets initialize the express app:

const app = express();

Lets add a middleware which converts the request body into json:

app.use(express.json());

Finally lets create a listener to accept incoming HTTP request on specific port:

app.listen(PORT, () => {
  console.log(`Server is running at http://localhost:${PORT}`);
});

Your Final app.js should look like this: 

const express = require("express");
const mongoose = require("mongoose");
const dotenv = require("dotenv");

dotenv.config({ path: ".env" });
const PORT = process.env.PORT;
const dbURI = process.env.DATABASE_URL;

//model
const Tasks = require("./models/todos");

const connect = mongoose.connect(dbURI, {
  useNewUrlParser: true,
  useUnifiedTopology: true,
});

connect.then(
  (db) => {
    console.log("Connected Successfully to Mongodb Server");

  },
  (err) => {
    console.log(err);
  }
);

const app = express();

app.use(express.json());

app.listen(PORT, () => {
  console.log(`Server is running at http://localhost:${PORT}`);
});

Now we are good to go with basic CRUD operations.