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Mongoose findById() Function

Last Updated : 08 Jan, 2024
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The findById() function is used to find a single document by its _id field. The _id field is cast based on the Schema before sending the command.

Syntax:

Model.findById(id)

Parameters:

  • Model: This is the name of the collection used to retrieve the document corresponding to the provided ID.
  • id: This is the identifier for the document you intend to locate.
  • callback`findById` also accepts a callback function, which can manage errors or perform actions with the retrieved document.

Steps to Install of Mongoose ModuleMongoose:

Step 1: You can visit the link Install Mongoose module. You can install this package by using this command.

npm install mongoose

Step 2: After installing the mongoose module, you can check your mongoose version in command prompt using the command.

npm version mongoose

Project Structure:

NodeProj

The updated dependencies in package.json file will look like:

"dependencies": {
"mongoose": "^7.6.5",
}

Step 3: After that, you can just create a folder and add a file for example index.js, To run this file you need to run the following command.

node index.js

Example: Below the code example for the findById() method:

javascript




const mongoose = require('mongoose');
 
// Database connection
    useNewUrlParser: true,
    useCreateIndex: true,
    useUnifiedTopology: true
});
 
// User model
const User = mongoose.model('User', {
    name: { type: String },
    age: { type: Number }
});
 
// Finding a document whose id=5ebadc45a99bde77b2efb20e
var id = '5ebadc45a99bde77b2efb20e';
User.findById(id, function (err, docs) {
    if (err){
        console.log(err);
    }
    else{
        console.log("Result : ", docs);
    }
});


Steps to run the program:

node index.js

Below is the sample data in the database before the function is executed, You can use any GUI tool or terminal to see the database, like we have used Robo3T GUI tool as shown below: DatabaseConsole Output:

So this is how you can use the mongoose findById() function to find a single document by its _id field.


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