Spring Boot and Hibernate One-to-One CRUD REST API Tutorial

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In this tutorial, we will demonstrate how to set up a one-to-one relationship between User and UserProfile entities using Spring Boot and Hibernate, and expose CRUD operations through a REST API.

Prerequisites

  1. Java Development Kit (JDK) 11 or higher: Ensure JDK is installed and configured on your system.
  2. Integrated Development Environment (IDE): IntelliJ IDEA, Eclipse, or any other IDE.
  3. Maven: Ensure Maven is installed and configured on your system.

Step 1: Create a Spring Boot Project

  1. Open your IDE and create a new Spring Boot project.
  2. Use Spring Initializr or manually create the pom.xml file to include Spring Boot and other required dependencies.
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>spring-boot-one-to-one-example</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.1.0</version>
        <relativePath/>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

Explanation

  • spring-boot-starter-data-jpa: Includes Spring Data JPA with Hibernate.
  • spring-boot-starter-web: Includes Spring MVC for building web applications.
  • h2: An in-memory database for testing purposes.

Step 2: Configure the Application Properties

Configure the application.properties file to set up the H2 database.

spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
spring.h2.console.enabled=true
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true

Step 3: Create the User Entity Class

Create a package named com.example.entity and a class named User.

package com.example.entity;

import jakarta.persistence.*;

@Entity
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String username;
    private String email;

    @OneToOne(mappedBy = "user", cascade = CascadeType.ALL, fetch = FetchType.LAZY, optional = false)
    private UserProfile userProfile;

    public User() {}

    public User(String username, String email) {
        this.username = username;
        this.email = email;
    }

    public Long getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public UserProfile getUserProfile() {
        return userProfile;
    }

    public void setUserProfile(UserProfile userProfile) {
        if (userProfile == null) {
            if (this.userProfile != null) {
                this.userProfile.setUser(null);
            }
        } else {
            userProfile.setUser(this);
        }
        this.userProfile = userProfile;
    }

    @Override
    public String toString() {
        return "User{id=" + id + ", username='" + username + '\'' + ", email='" + email + '\'' + '}';
    }
}

Explanation

  • @Entity: Marks the class as an entity.
  • @Id: Marks the field as the primary key.
  • @GeneratedValue: Specifies the strategy for generating values for the primary key.
  • @OneToOne: Defines a one-to-one relationship with the UserProfile entity.
  • mappedBy: Specifies the field in the UserProfile entity that owns the relationship.
  • cascade: Specifies the cascade operations.
  • fetch: Specifies the fetch type (lazy loading).
  • optional: Indicates whether the relationship is optional.

Step 4: Create the UserProfile Entity Class

Create a class named UserProfile in the same package.

package com.example.entity;

import jakarta.persistence.*;

@Entity
public class UserProfile {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String address;
    private String phoneNumber;

    @OneToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "user_id")
    private User user;

    public UserProfile() {}

    public UserProfile(String address, String phoneNumber) {
        this.address = address;
        this.phoneNumber = phoneNumber;
    }

    public Long getId() {
        return id;
    }

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

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getPhoneNumber() {
        return phoneNumber;
    }

    public void setPhoneNumber(String phoneNumber) {
        this.phoneNumber = phoneNumber;
    }

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    @Override
    public String toString() {
        return "UserProfile{id=" + id + ", address='" + address + '\'' + ", phoneNumber='" + phoneNumber + '\'' + '}';
    }
}

Explanation

  • @Entity: Marks the class as an entity.
  • @Id: Marks the field as the primary key.
  • @GeneratedValue: Specifies the strategy for generating values for the primary key.
  • @OneToOne: Defines a one-to-one relationship with the User entity.
  • @JoinColumn: Specifies the foreign key column.

Step 5: Create Repository Interfaces

Create a package named com.example.repository and interfaces for User and UserProfile.

package com.example.repository;

import com.example.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface UserRepository extends JpaRepository<User, Long> {}

package com.example.repository;

import com.example.entity.UserProfile;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface UserProfileRepository extends JpaRepository<UserProfile, Long> {}

Step 6: Create Service Classes

Create a package named com.example.service and service classes for User and UserProfile.

package com.example.service;

import com.example.entity.User;
import com.example.entity.UserProfile;
import com.example.repository.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class UserService {
    @Autowired
    private UserRepository userRepository;

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

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

    public User findById(Long id) {
        return userRepository.findById(id).orElse(null);
    }

    public void deleteById(Long id) {
        userRepository.deleteById(id);
    }
}

package com.example.service;

import com.example.entity.UserProfile;
import com.example.repository.UserProfileRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class UserProfileService {
    @Autowired
    private UserProfileRepository userProfileRepository;

    public UserProfile save(UserProfile userProfile) {
        return userProfileRepository.save(userProfile);
    }

    public List<UserProfile> findAll() {
        return userProfileRepository.findAll();
    }

    public UserProfile findById(Long id) {
        return userProfileRepository.findById(id).orElse(null);
    }

    public void deleteById(Long id) {
        userProfileRepository.deleteById(id);
    }
}

Step 7: Create Controller Classes

Create a package named com.example.controller and controller classes for User and UserProfile.

package com.example

.controller;

import com.example.entity.User;
import com.example.entity.UserProfile;
import com.example.service.UserService;
import com.example.service.UserProfileService;
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;

    @Autowired
    private UserProfileService userProfileService;

    @PostMapping
    public User createUser(@RequestBody User user) {
        if (user.getUserProfile() != null) {
            user.getUserProfile().setUser(user);
        }
        return userService.save(user);
    }

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

    @GetMapping("/{id}")
    public User getUserById(@PathVariable Long id) {
        return userService.findById(id);
    }

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

    @PostMapping("/{userId}/profile")
    public User addUserProfile(@PathVariable Long userId, @RequestBody UserProfile userProfile) {
        User user = userService.findById(userId);
        if (user != null) {
            userProfile.setUser(user);
            user.setUserProfile(userProfile);
            userService.save(user);
            return user;
        }
        return null;
    }

    @DeleteMapping("/{userId}/profile")
    public User removeUserProfile(@PathVariable Long userId) {
        User user = userService.findById(userId);
        if (user != null && user.getUserProfile() != null) {
            userProfileService.deleteById(user.getUserProfile().getId());
            user.setUserProfile(null);
            return userService.save(user);
        }
        return null;
    }
}

package com.example.controller;

import com.example.entity.UserProfile;
import com.example.service.UserProfileService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("/profiles")
public class UserProfileController {
    @Autowired
    private UserProfileService userProfileService;

    @PostMapping
    public UserProfile createUserProfile(@RequestBody UserProfile userProfile) {
        return userProfileService.save(userProfile);
    }

    @GetMapping
    public List<UserProfile> getAllUserProfiles() {
        return userProfileService.findAll();
    }

    @GetMapping("/{id}")
    public UserProfile getUserProfileById(@PathVariable Long id) {
        return userProfileService.findById(id);
    }

    @DeleteMapping("/{id}")
    public void deleteUserProfile(@PathVariable Long id) {
        userProfileService.deleteById(id);
    }
}

Step 8: Create Main Application Class

Create a package named com.example and a class named SpringBootOneToOneExampleApplication.

package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

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

Step 9: Run the Application

  1. Run the SpringBootOneToOneExampleApplication class.
  2. Use an API client (e.g., Postman) or a web browser to test the endpoints.

Testing the Endpoints

  1. Create a User:

    • URL: POST /users
    • Body: 
      {
  "username": "john_doe",
  "email": "[email protected]",
  "userProfile": {
    "address": "123 Main St",
    "phoneNumber": "123-456-7890"
  }
}

  2. Create User Profile:

    • URL: POST /profiles
    • Body: 
      {
  "address": "123 Main St",
  "phoneNumber": "123-456-7890"
}

  3. Get All Users:

    • URL: GET /users

  4. Get User by ID:

    • URL: GET /users/{id}

  5. Delete User by ID:

    • URL: DELETE /users/{id}

  6. Add User Profile to User:

    • URL: POST /users/{userId}/profile
    • Body: 
      {
  "address": "123 Main St",
  "phoneNumber": "123-456-7890"
}

  7. Remove User Profile from User:

    • URL: DELETE /users/{userId}/profile

  8. Get All User Profiles:

    • URL: GET /profiles

  9. Get User Profile by ID:

    • URL: GET /profiles/{id}

  10. Delete User Profile by ID:

  • URL: DELETE /profiles/{id}

Conclusion

You have successfully created an example using Spring Boot and Hibernate to demonstrate a one-to-one relationship between User and UserProfile entities. This tutorial covered setting up a Spring Boot project, configuring Hibernate, creating entity classes with a one-to-one relationship, and performing CRUD operations through RESTful endpoints.

Related Spring and Spring Boot Tutorials/Guides:

Spring Boot Tutorials [500+] Spring Boot Testing Tutorial Spring Boot Microservice Tutorial Spring Boot Kafka Microservices Spring Boot + Apache Kafka Tutorial Spring Core Tutorial Spring MVC Tutorial Spring Data JPA Tutorial Spring Framework for Beginners Spring AOP Tutorial Spring Security Tutorial Spring Exceptions Tutorial Spring Boot Interview Questions Spring Boot Microservices Interview Questions Apache Kafka Tutorials Docker Tutorials and Guides Spring Boot RabbitMQ Tutorials Angular CRUD Example with Spring Boot Spring Boot + Angular 12 CRUD Full Stack Spring Boot + Angular 8 CRUD Full Stack Spring Boot + Angular 10 CRUD Full Stack Spring Boot + React JS CRUD Full Stack React JS ( React Hooks) + Spring Boot Spring Boot Thymeleaf CRUD Full Stack Spring Boot User Registration and Login Node Js + Express + MongoDB CRUD Vue JS + Spring Boot REST API Tutorial

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