Social Media Backend

@RestController
@RequestMapping("/social")
public class SocialController {
}

// 1. User Entity
import jakarta.persistence.*;

@Entity
class SocialUser {

  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;

  private String username;
  private String email;
}


// 2. Post Entity
@Entity
class Post {

  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;

  private Long userId;
  private String content;
  private String imageUrl;
  private Long likesCount;
}


// 3. Comment Entity
@Entity
class Comment {

  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;

  private Long postId;
  private Long userId;
  private String text;
}


// 4. Repository Layer
import org.springframework.data.jpa.repository.JpaRepository;

interface UserRepository extends JpaRepository<SocialUser, Long> {}
interface PostRepository extends JpaRepository<Post, Long> {}
interface CommentRepository extends JpaRepository<Comment, Long> {}


// 5. Service Layer
import org.springframework.stereotype.Service;
import java.util.List;

@Service
class SocialService {

  private final PostRepository postRepo;
  private final CommentRepository commentRepo;

  public SocialService(PostRepository postRepo, CommentRepository commentRepo) {
    this.postRepo = postRepo;
    this.commentRepo = commentRepo;
  }

  public Post createPost(Post post) {
    post.setLikesCount(0L);
    return postRepo.save(post);
  }

  public Comment addComment(Comment comment) {
    return commentRepo.save(comment);
  }

  public List<Post> getFeed() {
    return postRepo.findAll();
  }

  public Post likePost(Long postId) {
    Post post = postRepo.findById(postId).orElseThrow();
    post.setLikesCount(post.getLikesCount() + 1);
    return postRepo.save(post);
  }
}


// 6. Controller Layer
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/social")
class SocialController {

  private final SocialService service;

  public SocialController(SocialService service) {
    this.service = service;
  }

  @PostMapping("/posts")
  public Post createPost(@RequestBody Post post) {
    return service.createPost(post);
  }

  @PostMapping("/comments")
  public Comment addComment(@RequestBody Comment comment) {
    return service.addComment(comment);
  }

  @GetMapping("/feed")
  public List<Post> getFeed() {
    return service.getFeed();
  }

  @PostMapping("/like/{id}")
  public Post likePost(@PathVariable Long id) {
    return service.likePost(id);
  }
}


// 7. application.properties
spring.datasource.url=jdbc:mysql://localhost:3306/social_media
spring.datasource.username=root
spring.datasource.password=root
spring.jpa.hibernate.ddl-auto=update


// Output:
// /social/posts -> Create post
// /social/comments -> Add comment
// /social/feed -> Get feed
// /social/like/{id} -> Like a post

• 1 System for managing posts and users.
• 2 Handles likes and comments.
• 3 Generates user feeds.
• 4 Built using Spring Boot backend.

• 1 User management
• 2 Post management
• 3 Comment system
• 4 Like system

• 1 User creates post
• 2 Other users interact
• 3 Likes and comments stored
• 4 Feed is generated

• 1 High scalability system
• 2 Real-world architecture learning
• 3 Microservices practice
• 4 Data-heavy application design