How to map specific column in entity class-CodePudding

I have two tables Users and UserRoles. These are the entity class I have created,

@Entity
@Table(name="users")
public Users {

@Id
@Column(name = "id")
private Long userId;

@ManyToOne(cascade=CaseCadeType.ALL)
@JoinColumn("user_role_id")
private UserRole userRole;

@Column(name = "user_name")
private String userName;
}


@Entity
@Table(name="users_Roles")
public UsersRoles {

@Id
@Column(name = "user_role_id")
private Long userRoleId;

@Column(name = "user_role_name")
private String userRoleName;
}

Repository Class,

@Repository
public interface UsersRepository extends JpaRepository<Users ,Long>{
 public List<Users> findByUserName(String userName);
}

For this I am able to get Json result like this.

[
 { 
   "userid":"1",
   "username":"user1",
   "userrole": {
    "userroleid":"1",
    "userrolename":"ADMIN",
   }
 },
   { 
   "userid":"2",
   "username":"user2",
   "userrole": {
    "userroleid":"2",
    "userrolename":"INTERN",
   }
}  

]

Instead of this can I get something like this..

 [
  { 
   "userid":"1",
   "username":"user1",
   "userrolename":"ADMIN",
   },
  { 
   "userid":"2",
   "username":"user2",
   "userrolename":"INTERN",
   }
]

What changes I need to do in my entity class for getting only userrolename in result.

CodePudding user response：

I think you will need to create a getter for userrolename:

public String getUserRoleName() {
  return userRole.getUserRoleName();
}

To ignore unwanted fields, annotate them with @JsonIgnore

CodePudding user response：

You can try to use the @Converter annotation in your entity. However this way you will have the string (or preferably an enum) in your entity and this will produce your wanted json.

CodePudding user response：

you can achieve this using DTOs and modelMapper library :

 <dependency>
    <groupId>org.modelmapper</groupId>
    <artifactId>modelmapper</artifactId>
    <version>current version</version>
</dependency>

public class UsersDTO {
    String userid ; 
    String username ;
    String userrolename ;
  }

UsersDTo dto= modelMapper.map(user, UsersDto.class);

another way is to instantiate the dto class in your repo

 @Query("SELECT new de.smarterco.example.dto.UsersDTO(u.id, u.username ,ur.name ) 
FROM Users u 
join u.UsersRoles  ur")
    List<UsersDTO> findUsersDTo();

And the final way to do this is using jpa projection by creating your dto as interface

public intefaceUsersDTO {
    String getuserid() ; 
    String username () ;
    String userRoleName ();
  }

and in your repo :

@Query("SELECT u.id , u.username ,ur.name as userRoleName  ) 
FROM Users u 
join u.UsersRoles  ur")
    List<UsersDTO> findUsersDTo();