4.2.1 Enabling Spring Data MongonDB

To get started with Spring Data MongoDB, you’ll need to add the Spring Data MongoDB starter to the project build. As with Spring Data Cassandra, Spring Data MongoDB has two separate starters to choose from: one reactive and one nonreactive. We’ll look at the reactive options for persistence in chapter 13. For now, add the following dependency to the build to work with the nonreactive MongoDB starter:

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

This dependency is also available from the Spring Initializr by checking the MongoDB check box under NoSQL.

By adding the starter to the build, autoconfiguration will be triggered to enable Spring Data support for writing automatic repository interfaces, such as those you wrote for JPA in chapter 3 or for Cassandra earlier in this chapter.

By default, Spring Data MongoDB assumes that you have a MongoDB server running locally and listening on port 27017. If you have Docker installed on your machine, an easy way to get a MongoDB server running is with the following command line:

$ docker run -p 27017:27017 -d mongo:latest

But for convenience in testing or developing, you can choose to work with an embedded Mongo database instead. To do that, add the following Flapdoodle embedded MongoDB dependency to your build:

<dependency>
  <groupId>de.flapdoodle.embed</groupId>
  <artifactId>de.flapdoodle.embed.mongo</artifactId>
  <!-- <scope>test</scope> -->
</dependency>

The Flapdoodle embedded database affords you all of the same convenience of working with an in-memory Mongo database as you’d get with H2 when working with relational data. That is, you won’t need to have a separate database running, but all data will be wiped clean when you restart the application.

Embedded databases are fine for development and testing, but once you take your application to production, you’ll want to be sure you set a few properties to let Spring Data MongoDB know where and how your production Mongo database can be accessed, as shown next:

spring:
  data:
    mongodb:
      host: mongodb.tacocloud.com
      port: 27017
      username: tacocloud
      password: s3cr3tp455w0rd
      database: tacoclouddb

Not all of these properties are required, but they’re available to help point Spring Data MongoDB in the right direction in the event that your Mongo database isn’t running locally. Breaking it down, here’s what each property configures:

• spring.data.mongodb.host —— The hostname where Mongo is running (default: localhost)
• spring.data.mongodb.port —— The port that the Mongo server is listening on (default: 27017)
• spring.data.mongodb.username —— The username for accessing a secured Mongo database
• spring.data.mongodb.password —— The password for accessing a secured Mongo database
• spring.data.mongodb.database —— The database name (default: test)

Now that you have Spring Data MongoDB enabled in your project, you need to annotate your domain objects for persistence as documents in MongoDB.