Implementing One to One Mapping in Spring Boot using JPA

Posted By : Shanu Kumar | 30-Apr-2018
Java

In this blog, I am going to continue my mapping series with entities in spring boot.

You can also check my last two blogs  One_to_Many mapping and Many To Many mapping

Today, I am going to write  One-to-One mapping relationship using JPA.

Consider the following tables, USER and USER_PROFILES.in User table, it makes sense to store user primary

details and store all the secondary detail in a separate table User_Profile.

Creating the Project

     --> Using Spring Initializr web tool  

Here we are going to generate the project from Spring Initializr web tool.

      1. Go to http://start.spring.io

      2. Click Switch to full version link to see all the options

      3. Enter Artifact as “demo” 

      4. Change Package Name to “com.example.app” 

      5. Select JPA, WEB and MYSQL dependencies.

      6. Click Generate Project to download the project.

Database and Logging Configuration

application.properties.

in this file, we configure our database credential like username, password and  URL according to

development environment configuration.  we find out application.properties file in src/main/resource/application.properties

server.port=9090
spring.jpa.hibernate.ddl-auto=update
spring.jpa.database-platform = org.hibernate.dialect.MySQL5Dialect
spring.datasource.url= jdbc:mysql://localhost:3306/one_to_one?autoReconnect=true&useSSL=false
spring.datasource.username=root
spring.datasource.password=root
# Hibernate

logging.level.org.hibernate.SQL=DEBUG
logging.level.org.hibernate.type=TRACE

9090 is default port to run the application and Scheme name is one_to_one.

Let's create our required Domain.

 Domain Models

For this, we create a package name with the model inside com.example.app.model and create the following classes inside this package.

1. User model 

package com.example.app.model;

import javax.persistence.*;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import javax.validation.constraints.Email;
import java.io.Serializable;

@Entity
@Table(name = "users")
public class User implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    
    @Column(name = "first_name")
    private String firstName;

    @Column(name = "last_name")
    private String lastName;
   
    @Email
    @Column(unique = true)
    private String email;

    @NotNull
    @Size(max = 10)
    private String password;

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

    }

    public User(String firstName, String lastName, String email, String password) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.email = email;
        this.password = password;
    }

    // Getters and Setters (Omitted for brevity)
}

2. Gender Enum

we are creating Enum class for to store the Gender of User inside com.example.app.model

Gender.java.

package com.example.app.model;

public enum Gender {
    MALE,
    FEMALE
}

3. UserProfile model

create UserProfile.java inside com.example.app.model package

package com.example.app.model;

import javax.persistence.*;
import javax.validation.constraints.Size;
import java.io.Serializable;
import java.util.Date;

@Entity
@Table(name = "user_profiles")
public class UserProfile implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "phone_number")
    @Size(max = 15)
    private String phoneNumber;

    @Enumerated(EnumType.STRING)
    @Column(length = 10)
    private Gender gender;

    @Temporal(TemporalType.DATE)
    @Column(name = "dob")
    private Date dateOfBirth;

    @Size(max = 100)
    private String address1;

    @Size(max = 100)
    private String address2;

    @Size(max = 100)
    private String street;

    @Size(max = 100)
    private String city;

    @Size(max = 100)
    private String state;

    @Size(max = 100)
    private String country;

    @Column(name = "zip_code")
    @Size(max = 32)
    private String zipCode;

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

    public UserProfile() {

    }

    public UserProfile(String phoneNumber, Gender gender, Date dateOfBirth, 
                       String address1, String address2, String street, String city, 
                       String state, String country, String zipCode) {
        this.phoneNumber = phoneNumber;
        this.gender = gender;
        this.dateOfBirth = dateOfBirth;
        this.address1 = address1;
        this.address2 = address2;
        this.street = street;
        this.city = city;
        this.state = state;
        this.country = country;
        this.zipCode = zipCode;
    }

    // Getters and Setters (Omitted for brevity)
}

we specify @OneToOne annotation in both mode but one entity is the owner of this relationship.

the owner of this relationship contains @JoinColumn annotation to Foreign Key define

Defining  Repositories

now we have to create a package name with repository inside com.example.app. and create the following interfaces inside this package.

1. UserRepository

package com.example.app.repository;

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

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

}

2. UserProfileRepository

package com.example.app.repository;

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

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

}

 That's all we need to create repository.

Now,Open the main class

 

 DemoApplication.java 

 

and write following code -

package com.example.app;

import com.example.app.model.User;
import com.example.jpa.model.Gender;
import com.example.app.model.UserProfile;
import com.example.app.repository.UserRepository;
import com.example.app.repository.UserProfileRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import java.util.Calendar;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class JpaManyToManyDemoApplication implements CommandLineRunner {

    @Autowired
    private UserRepository userRepo;

    @Autowired
    private UserProfileRepository userProfileRepo;

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

    @Override
    public void run(String... args) throws Exception {
       
        
        User user = new User("Shanu", "Kumar", "[email protected]",
                "nothing.1234");

        Calendar dateOfBirth = Calendar.getInstance();
        dateOfBirth.set(1995, 12, 16);

        
        UserProfile userProfile = new UserProfile("+91-8574857882", Gender.MALE, dateOfBirth.getTime(),
                "345", "2nd street", "sohna road, Badsahpur", "Gurugram",
                "Hariyana", "India", "122018");

        user.setUserProfile(userProfile);

        
        userProfile.setUser(user);

        userRepo.save(user);

       

    }
}

Now, time to Run Applcation.you can check you DB.

Hope so, You like this Article.

Thank you so much.

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About Author

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Shanu Kumar

Shanu has experience in Java EE & Java SE and also interested in EJB application. He has knowledge of SQL and worked on MYSQL & Oracle databases. He loves listening to music.

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