Mongoose Query.prototype.count() API
Last Updated :
11 Jan, 2023
The Mongoose Query API count() method is used to count all the documents from a collection that matches the filter object provided in the arguments.
Syntax:
Query.prototype.count(filter, callback)
Parameters: It accepts the following parameters as mentioned above and described below:
- filter: It is a mongoose object which identifies the existing documents to count.
- callback: It is a callback function that accepts 2 parameters: error and count.
Return type: It returns a Query object as a response.
Creating node application And Installing Mongoose:
Step 1: Create a node application using the following command:
mkdir folder_name
cd folder_name
npm init -y
touch main.js
Step 2: After completing the Node.js application, Install the required module using the following command:
npm install mongoose
Example 1: In this example, we will use this method to count the documents in the collection that have the name “Luffy”.
Filename: main.js
Javascript
const mongoose = require( 'mongoose' )
{
dbName: 'event_db' ,
useNewUrlParser: true ,
useUnifiedTopology: true
}, err => err ? console.log(err)
: console.log( 'Connected to database' ));
const personSchema = new mongoose.Schema({
name: {
type: String,
},
age: {
type: Number,
}
});
const personsArray = [
{
name: 'Luffy' ,
age: 20
},
{
name: 'Nami' ,
age: 20,
},
{
name: 'Zoro' ,
age: 35
}
]
const Person = mongoose.model( 'Person' , personSchema);
(async () => {
await Person.insertMany(personsArray);
const res = await Person.where({ name: "Luffy" }).count();
console.log({ res });
})()
|
Step to Run Application: Run the application using the following command from the root directory of the project:
node main.js
Output:
GUI Representation of the Database using MongoDB Compass:
Example 2: In this example, we will use this method to count the documents in the collection that have the age “35”.
Filename: main.js
Javascript
const mongoose = require( 'mongoose' )
{
dbName: 'event_db' ,
useNewUrlParser: true ,
useUnifiedTopology: true
}, err => err ? console.log(err)
: console.log( 'Connected to database' ));
const personSchema = new mongoose.Schema({
name: {
type: String,
},
age: {
type: Number,
}
});
const personsArray = [
{
name: 'Luffy' ,
age: 20
},
{
name: 'Nami' ,
age: 20,
},
{
name: 'Zoro' ,
age: 35
}
]
const Person = mongoose.model( 'Person' , personSchema);
(async () => {
await Person.insertMany(personsArray);
const res = await Person.where({ age: 35 }).count();
console.log({ res });
})()
|
Step to Run Application: Run the application using the following command from the root directory of the project:
node main.js
Output:
GUI Representation of the Database using MongoDB Compass:
Reference: https://mongoosejs.com/docs/api/query.html#query_Query-count
Share your thoughts in the comments
Please Login to comment...