MongoDB

MongoDB is an open-source NoSQL document database that uses a JSON-like schema instead of traditional table-based relational data. Spring Boot offers several conveniences for working with MongoDB, including the spring-boot-starter-data-mongodb and spring-boot-starter-data-mongodb-reactive “Starters”.

Connecting to a MongoDB Database

To access MongoDB databases, you can inject an auto-configured org.springframework.data.mongodb.MongoDatabaseFactory. By default, the instance tries to connect to a MongoDB server at mongodb://localhost/test. The following example shows how to connect to a MongoDB database:

Java
Kotlin

import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;
import org.bson.Document;

import org.springframework.data.mongodb.MongoDatabaseFactory;
import org.springframework.stereotype.Component;

@Component
public class MyBean {

	private final MongoDatabaseFactory mongo;

	public MyBean(MongoDatabaseFactory mongo) {
		this.mongo = mongo;
	}

	// ...

	public MongoCollection<Document> someMethod() {
		MongoDatabase db = this.mongo.getMongoDatabase();
		return db.getCollection("users");
	}

}

import com.mongodb.client.MongoCollection
import org.bson.Document
import org.springframework.data.mongodb.MongoDatabaseFactory
import org.springframework.stereotype.Component

@Component
class MyBean(private val mongo: MongoDatabaseFactory) {

	// ...

	fun someMethod(): MongoCollection<Document> {
		val db = mongo.mongoDatabase
		return db.getCollection("users")
	}

}

If you have defined your own MongoClient, it will be used to auto-configure a suitable MongoDatabaseFactory.

The auto-configured MongoClient is created using a MongoClientSettings bean. If you have defined your own MongoClientSettings, it will be used without modification and the spring.data.mongodb properties will be ignored. Otherwise a MongoClientSettings will be auto-configured and will have the spring.data.mongodb properties applied to it. In either case, you can declare one or more MongoClientSettingsBuilderCustomizer beans to fine-tune the MongoClientSettings configuration. Each will be called in order with the MongoClientSettings.Builder that is used to build the MongoClientSettings.

You can set the spring.data.mongodb.uri property to change the URL and configure additional settings such as the replica set, as shown in the following example:

Properties
YAML

spring.data.mongodb.uri=mongodb://user:secret@mongoserver1.example.com:27017,mongoserver2.example.com:23456/test

spring:
  data:
    mongodb:
      uri: "mongodb://user:secret@mongoserver1.example.com:27017,mongoserver2.example.com:23456/test"

Alternatively, you can specify connection details using discrete properties. For example, you might declare the following settings in your application.properties:

Properties
YAML

spring.data.mongodb.host=mongoserver1.example.com
spring.data.mongodb.port=27017
spring.data.mongodb.additional-hosts[0]=mongoserver2.example.com:23456
spring.data.mongodb.database=test
spring.data.mongodb.username=user
spring.data.mongodb.password=secret

spring:
  data:
    mongodb:
      host: "mongoserver1.example.com"
      port: 27017
      additional-hosts:
      - "mongoserver2.example.com:23456"
      database: "test"
      username: "user"
      password: "secret"

If spring.data.mongodb.port is not specified, the default of 27017 is used. You could delete this line from the example shown earlier.

You can also specify the port as part of the host address by using the host:port syntax. This format should be used if you need to change the port of an additional-hosts entry.

If you do not use Spring Data MongoDB, you can inject a MongoClient bean instead of using MongoDatabaseFactory. If you want to take complete control of establishing the MongoDB connection, you can also declare your own MongoDatabaseFactory or MongoClient bean.

If you are using the reactive driver, Netty is required for SSL. The auto-configuration configures this factory automatically if Netty is available and the factory to use has not been customized already.

MongoTemplate

Spring Data MongoDB provides a MongoTemplate class that is very similar in its design to Spring’s JdbcTemplate. As with JdbcTemplate, Spring Boot auto-configures a bean for you to inject the template, as follows:

Java
Kotlin

import com.mongodb.client.MongoCollection;
import org.bson.Document;

import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.stereotype.Component;

@Component
public class MyBean {

	private final MongoTemplate mongoTemplate;

	public MyBean(MongoTemplate mongoTemplate) {
		this.mongoTemplate = mongoTemplate;
	}

	// ...

	public MongoCollection<Document> someMethod() {
		return this.mongoTemplate.getCollection("users");
	}

}

import com.mongodb.client.MongoCollection
import org.bson.Document
import org.springframework.data.mongodb.core.MongoTemplate
import org.springframework.stereotype.Component

@Component
class MyBean(private val mongoTemplate: MongoTemplate) {

	// ...

	fun someMethod(): MongoCollection<Document> {
		return mongoTemplate.getCollection("users")
	}

}

See the MongoOperations Javadoc for complete details.

Spring Data MongoDB Repositories

Spring Data includes repository support for MongoDB. As with the JPA repositories discussed earlier, the basic principle is that queries are constructed automatically, based on method names.

In fact, both Spring Data JPA and Spring Data MongoDB share the same common infrastructure. You could take the JPA example from earlier and, assuming that City is now a MongoDB data class rather than a JPA @Entity, it works in the same way, as shown in the following example:

Java
Kotlin

import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.repository.Repository;

public interface CityRepository extends Repository<City, Long> {

	Page<City> findAll(Pageable pageable);

	City findByNameAndStateAllIgnoringCase(String name, String state);

}

import org.springframework.data.domain.Page
import org.springframework.data.domain.Pageable
import org.springframework.data.repository.Repository

interface CityRepository :
	Repository<City?, Long?> {
	fun findAll(pageable: Pageable?): Page<City?>?
	fun findByNameAndStateAllIgnoringCase(name: String?, state: String?): City?
}

You can customize document scanning locations by using the @EntityScan annotation.

For complete details of Spring Data MongoDB, including its rich object mapping technologies, see its reference documentation.