Building a JPA Repository and Service Layer for Contact Entity in Spring Boot

Programming & Development / April 18, 2025

Building a JPA Repository and Service Layer for Contact Entity in Spring Boot

Spring Boot JPA Contact Entity JPA repository contact Spring service layer example contact form backend Java Spring Boot CRUD JPA contact service implementation service interface Spring

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When building a contact form backend in a Spring Boot application, you typically need a database entity, a JPA repository, and a service layer to manage CRUD operations. In this post, we’ll walk through how to create a clean, layered backend for a simple Contact entity using Spring Boot and JPA.

📦 Step 1: Define the Contact Entity

Let’s start by defining the Contact class as a JPA entity:

java

import javax.persistence.*;

@Entity
public class Contact {

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

    private String name;
    private String email;
    private String subject;
    private String message;

    // Getters and setters
}

📁 Step 2: Create a JPA Repository

Create an interface that extends JpaRepository. This gives you CRUD methods out of the box.

java

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface ContactRepository extends JpaRepository<Contact, Long> {
}

⚙️ Step 3: Create a Service Interface

To maintain abstraction between your controller and the repository, define a service interface:

java

import java.util.List;

public interface ContactService {
    Contact saveContact(Contact contact);
    List<Contact> getAllContacts();
    Contact getContactById(Long id);
    Contact updateContact(Long id, Contact contact);
    void deleteContact(Long id);
}

🔧 Step 4: Implement the Service

Now implement the service interface with actual business logic:

java

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

import java.util.List;

@Service
public class ContactServiceImpl implements ContactService {

    @Autowired
    private ContactRepository contactRepository;

    @Override
    public Contact saveContact(Contact contact) {
        return contactRepository.save(contact);
    }

    @Override
    public List<Contact> getAllContacts() {
        return contactRepository.findAll();
    }

    @Override
    public Contact getContactById(Long id) {
        return contactRepository.findById(id)
                .orElseThrow(() -> new ResourceNotFoundException("Contact not found with id: " + id));
    }

    @Override
    public Contact updateContact(Long id, Contact contactDetails) {
        Contact contact = getContactById(id);
        contact.setName(contactDetails.getName());
        contact.setEmail(contactDetails.getEmail());
        contact.setSubject(contactDetails.getSubject());
        contact.setMessage(contactDetails.getMessage());
        return contactRepository.save(contact);
    }

    @Override
    public void deleteContact(Long id) {
        Contact contact = getContactById(id);
        contactRepository.delete(contact);
    }
}

🚨 Step 5: Add Custom Exception Handling (Optional)

To make your API more robust, define a custom exception for not found entities:

java

import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ResponseStatus;

@ResponseStatus(HttpStatus.NOT_FOUND)
public class ResourceNotFoundException extends RuntimeException {
    public ResourceNotFoundException(String message) {
        super(message);
    }
}

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