User Service

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Steps to Write an Api Service

• Understand the requirement of the Client
• Fix the database type
• Design the table (model)
• Write the Orm Layer
• Write the service layer
• Join with the controller and Done

Link to original

Okay So let’s start making this.

Requirement make a user Service

To make a database first we’ll have to decide which type of database

According to this document : How To choose a database for my System

Database for this should be relational so Postgres

Table Name : Users

Field Name	Data Type	Required	Indexed	Sample
email	string	yes	yes	joe@email.com
name	string	yes	no	joe
lastname	string	no	no	biden
password	string	yes	no	fnwenbqboojow2
role	string	yes	no	user
emailVerifiedAt	timestamp	yes	no	timestamp

User Service

Service Class : V0

Optional will be used a lot of places

package in.abhi8290.helloworld.user;  
  
import in.abhi8290.helloworld.core.base.BaseService;  
import org.springframework.stereotype.Service;  
  
import java.util.Optional;  
  
@Service  
public class UserService extends BaseService<User, String> {  
  
    private final UserRepository userRepository;  
  
    // Spring will inject this automatically  
    public UserService(UserRepository userRepository) {  
        this.userRepository = userRepository;  
    }  
  
    @Override  
    protected UserRepository getRepository() {  
        return userRepository;  
    }  
  
    public Optional<User> findByEmail(String email) {  
        return Optional.ofNullable(userRepository.findByEmail(email));  
    }  
  
    public boolean emailExists(String email) {  
        return userRepository.existsByEmail(email);  
    }  
}

Controller Class

package in.abhi8290.helloworld.user;  
  
import org.slf4j.Logger;  
import org.slf4j.LoggerFactory;  
import org.springframework.web.bind.annotation.*;  
  
import java.util.List;  
import java.util.Optional;  
import in.abhi8290.helloworld.user.*;  
  
@RestController  
@RequestMapping("/users")  
public class UserController {  
  
    private static final Logger logger = LoggerFactory.getLogger(UserController.class);  
  
    private final UserService userService;  
  
    // Spring will inject this for you  
    public UserController(UserService userService) {  
        this.userService = userService;  
    }  
  
    // GET all users  
    @GetMapping  
    public List<User> getAllUsers() {  
        return userService.findAll();  
    }  
  
    // GET user by email  
    @GetMapping("/by-email")  
    public Optional<User> getUserByEmail(@RequestParam String email) {  
        return userService.findByEmail(email);  
    }  
  
    // POST create a user  
    @PostMapping  
    public User createUser(@RequestBody User user) {  
        logger.info("Creating user with email: {}", user.getEmail());  
        return userService.save(user);  
    }  
}

Repo Class

• This is the most interesting All we need to write a function called findByEmail and JPA will go and make write the query for us check this out JPA Repository

package in.abhi8290.helloworld.user;  
  
import in.abhi8290.helloworld.core.base.BaseRepository;  
import org.springframework.stereotype.Repository;  
  
@Repository  
public interface UserRepository extends BaseRepository<User, String> {  
  
    User findByEmail(String email);  
  
    boolean existsByEmail(String email);  
  
    User findByFirstName(String firstName);  
  
  
}

Entity Class

package in.abhi8290.helloworld.user;  
  
import in.abhi8290.helloworld.core.base.BaseEntity;  
import jakarta.persistence.Column;  
import jakarta.persistence.Entity;  
import jakarta.persistence.Table;  
  
@Entity  
@Table(name = "users")  
public class User extends BaseEntity {  
  
    @Column(nullable = false)  
    private String firstName;  
  
    @Column(nullable = false)  
    private String lastName;  
  
    @Column(nullable = false)  
    private String password;  
  
    @Column(unique = true, nullable = false)  
    private String email;  
  
    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  
  
    public String getFirstName() {  
        return firstName;  
    }  
  
    public void setFirstName(String firstName) {  
        this.firstName = firstName;  
    }  
  
    public String getLastName() {  
        return lastName;  
    }  
  
    public void setLastName(String lastName) {  
        this.lastName = lastName;  
    }  
  
    public String getPassword() {  
        return password;  
    }  
  
    public void setPassword(String password) {  
        this.password = password;  
    }  
  
    public String getEmail() {  
        return email;  
    }  
  
    public void setEmail(String email) {  
        this.email = email;  
    }  
}