Skip to main content

Java Spring Boot code to connect to MongoDB

Here's an example Java Spring Boot code to connect to a MongoDB database:​

1. Add the MongoDB Java driver dependency to your pom.xml file:​

<dependency>
    <groupId>org.mongodb</groupId>
    <artifactId>mongodb-driver-sync</artifactId>
    <version>4.4.3</version>
</dependency>

2. Define the MongoDB connection properties in your application.properties file:​

spring.data.mongodb.uri=mongodb://localhost:27017/mydatabase

3. Create a MongoConfig class to configure the MongoDB connection:​

import com.mongodb.client.MongoClient;
import com.mongodb.client.MongoClients;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.mongodb.config.AbstractMongoClientConfiguration;
import org.springframework.data.mongodb.repository.config.EnableMongoRepositories;

@Configuration
@EnableMongoRepositories(basePackages = "com.example.myapp.repository")
public class MongoConfig extends AbstractMongoClientConfiguration {

    @Override
    protected String getDatabaseName() {
        return "mydatabase";
    }

    @Override
    @Bean
    public MongoClient mongoClient() {
        return MongoClients.create();
    }
}

This code creates a 'MongoConfig' class that extends 'AbstractMongoClientConfiguration' and overrides two methods: 'getDatabaseName()' and 'mongoClient()'. 'getDatabaseName()' returns the name of the MongoDB database, while 'mongoClient()' returns a MongoClient object that connects to the MongoDB server using the connection URI defined in 'application.properties'.

4. Use the MongoRepository interface to define your MongoDB repository:​

import org.springframework.data.mongodb.repository.MongoRepository;
import com.example.myapp.model.User;

public interface UserRepository extends MongoRepository<User, String> {
}

This code creates a UserRepository interface that extends MongoRepository and provides basic CRUD operations for the User class.

Now you can use UserRepository to interact with your MongoDB database. For example:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import com.example.myapp.model.User;
import com.example.myapp.repository.UserRepository;

@SpringBootApplication
public class MyApp implements CommandLineRunner {

    @Autowired
    private UserRepository userRepository;

    public static void main(String[] args) {
        SpringApplication.run(MyApp.class, args);
    }

    @Override
    public void run(String... args) throws Exception {
        // Create a new user
        User user = new User("John", "Doe", "john.doe@example.com");
        userRepository.save(user);

        // Find all users
        Iterable<User> users = userRepository.findAll();
        for (User u : users) {
            System.out.println(u);
        }
    }
}

This code creates a Spring Boot application that injects UserRepository and uses it to save a new user and retrieve all users from the MongoDB database. Note that you don't need to write any explicit code to connect to the database - Spring Boot takes care of it for you.