Mongoose count() Function
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 useNewUrlParser: true, useCreateIndex: true, useUnifiedTopology: true}); // User modelconst 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 useNewUrlParser: true, useCreateIndex: true, useUnifiedTopology: true}); // User modelconst 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
