Handling MongoDB operations using Mongoose

1. Connection to MongoDB using Mongoose:

Create a Database in MongoDB Atlas>

To create Database in MongoDB atlas refer: https://www.mongodb.com/docs/atlas/create-database-deployment/

    const connectionInstance = async()=>{

    try {
        const connection= await mongoose.connect("Connection URL")
        console.log("MogoDB connection successfull");
    } catch (error) {
        console.log("MongoDB Error: ", error)
        process.exit(1)
    }

}

2. Create Basic Schema

In Mongoose, a schema serves as a blueprint for defining the structure of a Mongoose model. Let’s break it down:

1. Schema Definition:

   • A schema is a configuration object that specifies how the data in a Mongoose model should be organized.

   • It defines the fields, their types, default values, and any validation rules that should be applied to the data.

2. Model vs. Schema:

   • A model represents a MongoDB collection and provides an interface for creating, querying, updating, and deleting records based on the schema.

   • A schema, on the other hand, defines the structure of a document or record within that collection.

3. What Schemas Do:

   • Define the properties that documents saved in MongoDB can have.

   • Declare custom validation rules.

   • Specify virtuals (computed properties).

   • Define getters and setters for transforming data.

   • Declare static methods for querying the database based on the schema.

    import mongoose from "mongoose";      

const userSchema= new mongoose.Schema({
    firstname:{
        type:String,
        required: true
    },
    lastname:{
        type:String,
        required: true
    },
    email:{
        type:String,
        required: true
    },
    dob:{
        type:Date,
        required: true
    },

},{timestamps:true})

export const User= mongoose.model("User",userSchema)

//it will create a database for the define shema and set the name in lowercase in pulalr form 
//e.g User --> users

3. Fetch All records

To fetch records we can use find() method. Generally find method will take a filter ({name:"somename"}) in the argument but to fetch all records you can just give {} in argument

    //get all records(files) from MongoDB
    const users=await User.find({})
    console.log(users);

4. Insert new Record

    // Inser new user in MongoDb using Mongoose

    const newUser = new User()
    newUser.firstname="Akash"
    newUser.lastname="Chauhan"
    newUser.email="akash@akash.com"
    newUser.dob=Date.now()

    const savedUser= await newUser.save()
    console.log(savedUser);

5. Update the Records

By fetching the records and update it and then save the schema using save method

    const userToBeUpdated= await User.findOne({firstname:"Akash"})
    console.log("User: ", userToBeUpdated);
    userToBeUpdated.email="akash.akash@gmail.com"
    const updatedUser=await userToBeUpdated.save()
    console.log("updated User: ", updatedUser);

By moongoose FindOneAndUpdate method

    const updatedUser= await User.findOneAndUpdate(
    {
        firstname:"Akash" //filter for which name you want to change the values
    },
    {
        email:"akas.akash@akash.com" //Values that you want to change
    },
    {
        new:true
    }
    )
    console.log(updatedUser);