Using Local Cassandra DB in Spring Boot Application

To create a Spring Boot application to perform CRUD (Create, Read, Update, Delete) operations in a Cassandra database, you'll need to follow these steps:

Step 1: Set Up Your Spring Boot Project

Create a new Spring Boot project using your preferred IDE or Spring Initializr. Include the following dependencies:

• Spring Web
• Spring Data Cassandra

Step 2: Configure Cassandra Connection

Update application.properties to include the Cassandra connection settings:

spring.data.cassandra.contact-points=127.0.0.1
spring.data.cassandra.port=9042
spring.data.cassandra.keyspace-name=my_keyspace

Replace my_keyspace with the name of your Cassandra keyspace.

Step 3: Create an Entity Class

Create a Java class to represent your data model. This class will map to a table in Cassandra.

import org.springframework.data.annotation.Id;
import org.springframework.data.cassandra.core.mapping.PrimaryKey;
import org.springframework.data.cassandra.core.mapping.Table;

@Table
public class User {

    @Id
    @PrimaryKey
    private String id;

    private String name;
    private String email;

    // Getters and setters
}

Step 4: Create a Repository Interface

Create a Spring Data repository interface to perform CRUD operations on the User entity.

import org.springframework.data.cassandra.repository.CassandraRepository;

public interface UserRepository extends CassandraRepository<User, String> {
}

Step 5: Implement CRUD Operations

Create a service class to implement CRUD operations using the repository.

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.Optional;

@Service
public class UserService {

    @Autowired
    private UserRepository userRepository;

    public List<User> getAllUsers() {
        return userRepository.findAll();
    }

    public Optional<User> getUserById(String id) {
        return userRepository.findById(id);
    }

    public User createUser(User user) {
        return userRepository.save(user);
    }

    public User updateUser(User user) {
        return userRepository.save(user);
    }

    public void deleteUser(String id) {
        userRepository.deleteById(id);
    }
}

Step 6: Create REST Controller

Create a REST controller to expose CRUD endpoints.

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("/users")
public class UserController {

    @Autowired
    private UserService userService;

    @GetMapping
    public List<User> getAllUsers() {
        return userService.getAllUsers();
    }

    @GetMapping("/{id}")
    public User getUserById(@PathVariable String id) {
        return userService.getUserById(id)
                .orElseThrow(() -> new RuntimeException("User not found"));
    }

    @PostMapping
    public User createUser(@RequestBody User user) {
        return userService.createUser(user);
    }

    @PutMapping("/{id}")
    public User updateUser(@PathVariable String id, @RequestBody User user) {
        user.setId(id);
        return userService.updateUser(user);
    }

    @DeleteMapping("/{id}")
    public void deleteUser(@PathVariable String id) {
        userService.deleteUser(id);
    }
}

Step 7: Run the Application

Run your Spring Boot application and test the CRUD operations using a REST client like Postman or curl.

That's it! You have now created a Spring Boot application to perform CRUD operations in a Cassandra database. You can further customize and extend this application to suit your requirements.