How to Connect MongoDB with Spring Boot?

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In recent times MongoDB has been the most used database in the software industry. It’s easy to use and learn This database stands on top of document databases it provides the scalability and flexibility that you want with the querying and indexing that you need. In this, we will explain how we connect MongoDB with Spring Boot.

Prerequisites:

Before starting the below software must be installed in your system.

Java
Any Spring Boot Supported IDE like STS (Spring Tool Suite), IntelliJ IDE, etc.
MongoDB

Adding Dependencies

Add the below dependencies in the pom.xml file.

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-mongodb</artifactId>
</dependency>
<dependency>
     <groupId>org.springframework.boot</groupId>
     <artifactId>spring-boot-starter-web</artifactId>
</dependency>

Below is the above dependency in pom.xml file for your reference.

MongoDB Connection Properties:

There is some important parameter we need to know to connect the MongoDB server with Spring Boot.

Port (By Default Port – 27017)
Host (By Default Host – localhost)
Database Name
Credential (Optional)

To connect to the MongoDB server, configure the following parameters in your application.properties file:

spring.data.mongodb.host=localhost
spring.data.mongodb.port=27017
spring.data.mongodb.database=demo
spring.data.mongodb.username=username_value  (optional)
spring.data.mongodb.password=password_value (optional)

Note: If there is no username and password set in your MongoDB, you can use the default URI format.

spring.data.mongodb.uri=mongodb://your_username:your_password@localhost:27017/demo

Note:

demo (Database Name)
By default, you can use like this (if there is no username and password set in your MongoDB) => “spring.data.mongodb.uri=mongodb://localhost:27017/demo”
By default, we do not need a user and password.

Connect MongoDB with Spring Boot Example Project

For Example, we are using STS (Spring Tool Suite) IDE, and we have created a new Project and added these Spring Data MongoDB, and Spring web dependencies to our project.

Step 1: Create the “User” Class

Create a User class and annotate it with @Document. This class will represent your MongoDB document.

Java

import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.Document;

@Document
public class User {
    @Id
    private String userId;
    private String name;
    private String rollNumber;
    
    public User(String name, String rollNumber) {
        super();
        this.name = name;
        this.rollNumber = rollNumber;
    }
    public String getUserId() {
        return userId;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getRollNumber() {
        return rollNumber;
    }
    public void setRollNumber(String rollNumber) {
        this.rollNumber = rollNumber;
    }
}

Step 2: Create the Repository Interface

We will create an Interface that will extend MongoRepository with the help of this interface we will perform CRUD (Create, Read, Update, Delete) operation in our database.

Note:

Please keep in mind if you want to create one or more document (Table) for that every document (Table) you need to define a new interface that will extend MongoRepository.
MongoRepository<User,String> here “User” is my class name and “String” is my ID data type that we already defined in the User class and annotated with “@Id”.

Java

import org.springframework.data.mongodb.repository.MongoRepository;

public interface UserRepository extends MongoRepository<User,String>{

}

Step 3: Define MongoDB Connection Parameters

We will define important connection parameters for the MongoDB server. In the application.properties file, define the connection parameters:

Note: # means that line of code is commented.

#spring.data.mongodb.host=localhost
#spring.data.mongodb.port=27017
#spring.data.mongodb.database=userDatabase
server.port=8081
spring.data.mongodb.uri=mongodb://localhost:27017/userDatabase

Step 4: Create the Controller Class

Now this is the final step in this step we will create the controller class from there we will perform CRUD operation in our database.

We annotate the controller class with @RestController.
We create an object of our repository and annotate it with @Autowired.

Java

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class UserController {
    
    @Autowired 
    private UserRepository userRepo;
    
    // Save method is predefine method in Mongo Repository
    // with this method we will save user in our database
    @PostMapping("/addUser")
    public User addUser(@RequestBody User user) {
        return userRepo.save(user);
    }
    
    // findAll method is predefine method in Mongo Repository 
    // with this method we will all user that is save in our database
    @GetMapping("/getAllUser")
    public List<User> getAllUser(){
        return userRepo.findAll(); 
    }
}

Step 5: Testing with Postman

To test the endpoints, you can use Postman:

Note:

MongoDB automatically generates a unique ID for each document.
The JSON keys in the request body must match the variable names in the User class.

Output:

After executing the above steps, you should be able to add and retrieve user documents from your MongoDB database.

Add User: Send a POST request to http://localhost:8081/addUser with a JSON body containing name and rollNumber.

Get All Users: Send a GET request to http://localhost:8081/getAllUsers.

Conclusion

Connecting MongoDB with Spring Boot is straightforward and provides a robust way to manage your data. By following these steps, you can easily integrate MongoDB into your Spring Boot application and perform CRUD operations efficiently.

Tags:

#Java-Spring-Boot #Advance Java

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