Mongo-backed sessions

The spring-session-data-mongodb module stores sessions in MongoDB through the reactive Mongo driver — a natural choice when your application already uses Spring Data Mongo.

Step 1: add the dependencies

<dependency>
    <groupId>org.springframework.session</groupId>
    <artifactId>spring-session-data-mongodb</artifactId>
    <version>3.5.7</version>
</dependency>
<dependency>
    <groupId>org.springframework.data</groupId>
    <artifactId>spring-data-mongodb</artifactId>
</dependency>
<dependency>
    <groupId>org.mongodb</groupId>
    <artifactId>mongodb-driver-reactivestreams</artifactId>
</dependency>

Step 2: configure the Mongo connection

@Configuration
public class MongoConfig extends AbstractReactiveMongoConfiguration {

    @Value("${mongo.uri}")
    String mongoUri;

    @Override
    public MongoClient reactiveMongoClient() {
        return MongoClients.create(mongoUri);
    }

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

With the connection property set in application.properties:

server.port=8080
mongo.uri=mongodb://localhost:27017/

Start a MongoDB server for local development:

docker-compose up mongodb

Step 3: enable Mongo web session

@Configuration
@EnableMongoWebSession
public class SessionConfig {
}

@EnableMongoWebSession registers a reactive session repository backed by MongoDB automatically. The controller and template code is identical to the in-memory example.

Verify

Start the application, submit the attribute form at http://localhost:8080, and inspect the blog database — the sessions live in a dedicated collection with the attributes and a TTL index for expiry.

You can explore the complete codes in spring-reactive-sample/session-data-mongo.