Spring Boot MongoDB Configuration: Easy Steps

MongoDB is highly elastic and lets you combine and store multivariate data without compromising on the powerful indexing options, data access, and validation rules. On the other hand, Spring Boot is a microframework that is used by the developer community to build stand-alone applications. Spring Boot is an open-sourced application and is useful if you want to develop REST API.

The Spring Boot MongoDB Configuration is part of the Spring Data Project. It aims to create an amicable environment for developers aiming to build a Spring-based programming model. The Spring Boot MongoDB Configuration is a powerful integration you can create new datasets while also keeping hold of “store-specific features and capabilities.”

This tutorial article will discuss the Spring Boot MongoDB Configuration in detail.

Table of Content

1. What is MongoDB?
2. What is SpringBoot?
   • Key Features of SpringBoot
3. Spring Boot MongoDB Configuration
   • Create Spring project
   • Setup XML Configuration
   • Setup Java Configuration
   • Define Simple Entity
   • Running CRUD Operations
4. Conclusion

What is MongoDB?

MongoDB is a document-oriented open-source NoSQL database. It stores the data in documents and supports NoSQL query language to interact with data. MongoDB is very popular among organizations due to its features. 

NoSQL database means it does not store the data in rows and columns compared to traditional databases but instead uses documents that collect key-value pairs to store the data. Key-Value pair allows MongoDB to store the data schemaless and scale them vertically when needed without disrupting the data model. It keeps the data into a storage format known as BSON (Binary Style of JSON document). 

What is Spring Boot?

Spring Boot is a framework that is built on top of the Spring framework. SpringBoot simplifies the Spring framework by providing pluggable dependencies like Spring Kafka, Spring Web Services, Spring Security, and many more. 

Spring Boot is gaining popularity nowadays because it has Java as its programming language, and it helps developers build enterprise-grade applications very quickly with minimal configurations.

Key Features of Spring Boot

1. Spring Boot applications are auto configurable, which means that they can be configured via a list of dependencies or simply by a properties file. For example, if you list MySQL as a dependency, the SpringBoot application will start with MySQL connector included, which allows you to work seamlessly.

2. Spring Boot application can run on standalone mode, i.e., on one’s machine/laptop. Users don’t need a separate webserver to deploy the application.

3. Spring Boot provides many options while configuring, and hence if you include JPA in your Pom.xml, it will automatically configure a memory database, hibernate entity, and sample data source. This feature makes SpringBoot an Opinionated framework.

4. SpringBoot Framework reduces the overall development time and increases the team’s productivity by avoiding boilerplate code, configurations, and many more.

5. Spring Boot framework makes it easy for developers to create and test Java-based applications by providing a default setup for unit and integration tests.

Spring Boot MongoDB Configuration

The Spring Boot MongoDB Configuration is relatively simple and involves few steps for configuration. SpringBoot allows users to interact with MongoDB via two methods, MongoTemplate and MongoRepository.

The MongoTemplate follows the standard template and provides a ready-to-go basic API. The MongoRepository follows the Spring Data-centric approach with more flexible and complex API operations.

In this article, we will focus on interacting with MongoDB via MongoRepository. Let us look at how to perform operations with the Spring Boot MongoDB Configuration

Before going through the steps, let us look at the pre-requisites – 

1. You need a running MongoDB server. To setup a MongoDB server, you can refer  MongoDB Quick Start guide
2. Spring Boot framework installed on your machine.

Now that the Spring Boot MongoDB Configuration framework is set up, let us look at the step-by-step approach to configure MongoDB with SpringBoot.

Step 1: Create Spring Project.

1. Launch SpringBoot STS.
2. Navigate to File> New > Spring Template Project > Simple Spring Utility Project
3. Enter the project name and package name (say – org.spring.mongo.demo)
4. In the pom.xml, add the following dependencies – 

<dependencies>

  <!-- other dependency elements omitted -->

  <dependency>
    <groupId>org.springframework.data</groupId>
    <artifactId>spring-data-mongodb</artifactId>
    <version>3.3.1</version>
  </dependency>

</dependencies> 

Step 2: Setup XML configurations

1. Now that you have SpringBoot setup, it’s time to configure some XML for MongoDB configuration.
2. You will find mongoConfig.xml under the src folder in your SpringBoot project.
3. Update the File with the following information:

<mongo:mongo-client id="mongoClient" host="localhost" />
<mongo:db-factory id="mongoDbFactory" dbname="test" mongo-client-ref="mongoClient" />

<bean id="mongoTemplate" class="org.springframework.data.mongodb.core.MongoTemplate"> 
<constructor-arg ref="mongoDbFactory"/> 
</bean>

<mongo:repositories base-package="org.spring.mongo.demo" mongo-template-ref="mongoTemplate"/>

Step 3: Setup Java Configurations

1. Now that we have XML’s configured, we need to configure Java classes by extending the base class for MongoDB configuration.

@Configuration
@EnableMongoRepositories(basePackages = "org.spring.mongo.demo")
public class MongoConfig extends AbstractMongoClientConfiguration {

    private final List<Converter<?, ?>> converters = new ArrayList<Converter<?, ?>>();

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

    @Override
    public MongoClient mongoClient() {
        final ConnectionString connectionString = new ConnectionString("mongodb://localhost:27017/test");
        final MongoClientSettings mongoClientSettings = MongoClientSettings.builder()
            .applyConnectionString(connectionString)
            .build();
        return MongoClients.create(mongoClientSettings);
    }

    @Override
    public Collection<String> getMappingBasePackages() {
        return Collections.singleton("org.spring.mongo.demo");
    }

2. Once the configurations are done, create a repository to interact with MongoDB.

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

Step 4: Define simple entity

1. Define the simple entity User, with the parameter as Name, Age

public class User {

  @Id
  public String id;

  public String name;

  public User() {}

  public User(String name) {
    this.name = name;

  }

  @Override
  public String toString() {
    return String.format(
        "User[id=%s, name='%s']",
        id, name);
  }

}

Step 5: Running CRUD Operations

1. Once we set up the repository, the repository has several inbuilt methods to perform read-write operations in MongoDB. Some of them are – 
   1. Insert
   2. Save
   3. Update
   4. Delete
2. Create an application class to run simple queries against MongoDB collection – 

@SpringBootApplication
public class AccessingDataMongodbApplication implements CommandLineRunner {

  @Autowired
  private UserRepository repository;

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

  @Override
  public void run(String args) throws Exception {

    repository.deleteAll();

	// Add the below codes here to perform CRUD operations

  }

}

Let ‘s discuss how to implement the Spring Boot MongoDB Configuration.

1. Insert – 

Insert API inserts a new user in MongoDB collection. Run the below code to see the output.

User user = new User();
user.setName("Jon");
repository.insert(user);

The output of the command will be –

{
    "_id" : ObjectId("xxxxx"),
    "_class" : "org.spring.mongo.demo.model.User",
    "name" : "Jon"
}

2. Save-Insert

Save-Insert is similar to insert but has a different API.

User user = new User();
user.setName("Aaron");
repository.save(user);

The output of the command will be – 

{
    "_id" : ObjectId("xxxx"),
    "_class" : "org.spring.mongo.demo.model.User",
    "name" : "Aaron"
}

3. Save-Update

Save-Update is an API that updates the existing data in MongoDB.

The initial state of the database is – 

{
    "_id" : ObjectId("xxxx"),
    "_class" : "org.spring.mongo.demo.model.User",
    "name" : "Roy"
}

Now we execute the operation:

user = mongoTemplate.findOne(
  Query.query(Criteria.where("name").is("Roy")), User.class);
user.setName("Jim");
repository.save(user);

{
    "_id" : ObjectId("xxxx"),
    "_class" : "org.spring.mongo.demo.model.User",
    "name" : "Jim"
}

4. Delete

Delete API deletes the existing users from the MongoDB collection. 

Here’s the current state of the database – 

{
    "_id" : ObjectId("xxxx"),
    "_class" : "org.spring.mongo.demo.model.User",
    "name" : "Benn"
}

Let’s run delete:

repository.delete(user);

And here’s our result:

{
}

There are many more in-built APIs available in MongoDB Repository methods. You can get the list of all the methods on the STS console.

Conclusion

In this blog post, we have a detailed step-by-step procedure to enable the Spring Boot MongoDB Configuration.

For better judgment and understanding of the Spring Boot MongoDB Configuration, either of these two articles can help:

1. Spring Boot Integration with MongoDB Tutorial
2. Spring Data MongoDB – Reference Documentation

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