Mongoose - CRUD Operations

Mongoose has a flexible API and provides many ways to accomplish a task. We will not focus on the variations because that is out of scope for this article, but remember that most of the operations can be done in more than one way either syntactically or via the application architecture.

Create Record

Let’s create a todo and save into our database:

let newTask = {
      description: "task added using create",
};


Tasks.create(newTask)
  .then((data) => {
      console.log(data);
   })
   .catch((err) => {
      console.log(err);
});

Firstly we had created a newTask object with description of a todo which is a mandatory field required to create a document in the database. Mongoose model has a create() method which is a promise and on successful we get the response in data and in-case of failure it is catched and error is  displayed.

Find All Tasks

To get all the documents stored inside a collection.

//all tasks
    
Tasks.find({})
   .then((data) => {
       console.log("All tasks", data);
    })
    .catch((err) => {
       console.log(err);
 });

Find A Single Document or Record

Lets see how we can find a single document from the collection.

 //find with condition
     
  Tasks.find({ completed: false })
    .then((data) => {
         console.log("All tasks", data);
     })
     .catch((err) => {
         console.log(err);
    });

Update a Document

Let’s modify the record by updating the status completed:false to completed:true

    Tasks.findByIdAndUpdate({ _id: req.params.id },{
            $set: {completed:true},
          },
          { new: true, useFindAndModify: false } //get updated result
       )
       .then((data) => {
         console.log("Updated todo data", data);
       })
       .catch((err) => {
         console.log(err);
       });

Delete a document from the collection

 //delete all tasks
     Tasks.remove({});

// delete specific task

    Tasks.findByIdAndRemove(task_id)
       .then((data) => {
         console.log("All tasks", data);
       })
       .catch((err) => {
         console.log(err);
       });

In the above example replace the task_id with the value of _id of a task in mongoDB databse which looks like 5a78fe3e2f44ba8f85a2409a

So we have seen all  the CRUD operations namely, create, read, update, delete

Lets use them in our app.js file.

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");

    //all tasks
    Tasks.find({})
      .then((data) => {
        console.log("All tasks", data);
      })
      .catch((err) => {
        console.log(err);
      });

    // similary use all the other operation here

    // CAUTION: don't put all the operation together, use one operation
    // at a time
  },
  (err) => {
    console.log(err);
  }
);

const app = express();

app.use(express.json());

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

Now, run your server by using following command

first install,

npm install -g nodemon

then,

nodemon app.js