Mongoose count() Function

Last Updated : 10 Sep, 2020

The Query.prototype.count() function is used to count the number of documents in a collection. This functions basically specifies this query as a count query.

Syntax:

Query.prototype.count()

Parameters: This function accepts one array parameter i.e. callback function.

Return Value: This function returns Query Object.

Installation of mongoose module:

You can visit the link to Install mongoose module. You can install this package by using this command.

npm install mongoose

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

npm version mongoose

After that, you can just create a folder and add a file for example, index.js as shown below.

Database: The sample database used here is shown below:

Example 1: Filename: index.js

javascript

const mongoose = require('mongoose');
  
// Database connection
mongoose.connect('mongodb://127.0.0.1:27017/geeksforgeeks', {
    useNewUrlParser: true,
    useCreateIndex: true,
    useUnifiedTopology: true
});
  
// User model
const User = mongoose.model('User', { 
    name: { type: String },
    age: { type: Number }
});
  
var query = User.find();
query.count(function (err, count) {
    if (err) console.log(err)
    else console.log("Count is", count)
});

Steps to run the program:

The project structure will look like this:

Run index.js file using below command:

node index.js

Output:

Count is 4

Example 2: Filename: index.js

javascript

const express = require('express');
const mongoose = require('mongoose');
const app = express()
  
// Database connection
mongoose.connect('mongodb://127.0.0.1:27017/geeksforgeeks', {
    useNewUrlParser: true,
    useCreateIndex: true,
    useUnifiedTopology: true
});
  
// User model
const User = mongoose.model('User', { 
    name: { type: String },
    age: { type: Number }
});
  
var query = User.find();
query.count(function (err, count) {
    if (err) console.log(err)
    else console.log("Count:", count)
});
  
app.listen(3000, function(error ) {
    if(error) console.log(error)
    console.log("Server listening on PORT 3000")
});

Steps to run the program:

The project structure will look like this:

Run index.js file using below command:

node index.js

Output:

Server listening on PORT 3000
Count: 4

Reference: https://mongoosejs.com/docs/api/query.html#query_Query-count

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