How to integrate MongoDB with the Spring Boot application

In today’s growing world with increasing data applications and parameters for a single entity, which leads to a non-sql database. So in a few minutes, we are gonna integrate MongoDB with our Spring boot application.

Example Integration with MongoDB

Step 1: Add Dependencies

First, you need to add the required dependency in pom.xml. You need to add the MongoDB library which will help us to connect to the MongoDB server.

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

Step 2: Create a POJO class

Create a POJO class name student which will reflect as a collection in our database and we will gonna use @Document(collection = ”students”) annotation which will represent a collection name in the database.

@Document(collection = "students")
public class Student {

    private int id;
    private String name;
    private String city;
    private String college;

    public Student(String college, String city, String name, int id) {
        this.college = college;
        this.city = city;
        this.name = name;
        this.id = id;
    }

    public int getId() {
        return id;
    }

    public String getCollege() {
        return college;
    }

    public String getCity() {
        return city;
    }

    public String getName() {
        return name;
    }

    public void setId(int id) {
        this.id = id;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setCity(String city) {
        this.city = city;
    }

    public void setCollege(String college) {
        this.college = college;
    }
}

Step 3: Create a Repository Interface

We need to create one Repository interface that will help us to do operations on the MongoDB collection. This interface will extend MongoRepository<Student, Integer>which helps us to map the student data with the integer key.

public interface StudentRepo extends MongoRepository<Student, Integer> {
}

Step 4: Add a Controller class for Rest Operations

Next, we will gonna add a controller class for doing some REST operations which will help us to add and view data in the collection.

@RestController
public class MyController {

    @Autowired
    private StudentRepo studentRepo;

    @PostMapping("/student")
    public ResponseEntity<?> addStudent(@RequestBody Student student) {
        Student save = this.studentRepo.save(student);
        return ResponseEntity.ok(save);
    }

    @GetMapping("/")
    public ResponseEntity<?> getStudents() {
        return ResponseEntity.ok(this.studentRepo.findAll());
    }

    @GetMapping("/{id}")
    public ResponseEntity<?> getStudentsById(@PathVariable int id) {
        return ResponseEntity.ok(this.studentRepo.findById(id));
    }
}

The above code helps us to add the following operations:

1. @PostMapping(“/student”): This will help us to add new entry in our collection.
2. @GetMapping(“/”): This will help us to get all the data that is stored in the given collection.
3. @GetMapping(“/{id}”): This will get data based on the given id.

Step 5: Configuring MongoDB

Next, we’ll gonna add MongoDB port, host, and database in application.propertiesfile.

spring.data.mongodb.host=localhost
spring.data.mongodb.port=27017
spring.data.mongodb.database=demo

Conclusion

MongoDB integration is easy and helps us to do a lot of operations without writing actual statements, unlike SQL databases.