How to design classes in spring boot for 3 different roles?-CodePudding

I am working on an spring boot application which deals with distribution management. There are 3 types of user who will interact with the system - admin, distributor and retailer.

There can be only one administrator of a company.
There can be only one distributor in a city of a particular company.
Retailer can be linked with with distributors of different companies of a specific city.

Now, for this stuff. I have created 5 classes - User, Role, Administrator, Distributor, and Retailer. Can please anyone suggest me that how should I approach this problem with respect to designing the required classes. I tried initially but still I am thinking that this classes structure is complex in itself. Is there something which I am missing out or is there any design pattern which can make things quite more understable ??

@Entity
@Table(name = "tbl_User")
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    @Column(name = "user_id")
    private Long userId;
    
    @NotNull(message = "first Name cannot be null")
    @Column(name = "first_Name")
    private String firstName;
    
    @NotNull(message = "last Name cannot be null")
    @Column(name = "last_Name")
    private String lastName;
    
    @ManyToOne()
    @JoinColumn(name = "role_Id")
    private Role role;
    
    @NotNull
    @Size(min = 10, max = 10, message = "Contact must be of 10 characters")
    @Column(name = "contact")
    private String contact;
    
    @NotNull
    @Email(message = "Email should be valid")
    @Column(name = "email", unique = true)
    private String email;
    
    @NotNull
    @Size(min = 10, max = 255, 
    message = "Local address must be between 10 and 255 characters")
    @Column(name = "local_Address")
    private String localAddress;
    
    @ManyToOne()
    @JoinColumn(name = "city_Id")
    private City city;
    
    @NotNull
    @Column(name = "user_Name")
    private String userName;
    
    @NotNull
    @Column(name = "password")
    private String password;
    
    @Column(name = "registered_On")
    private LocalDateTime registeredOn;
    
    @Column(name = "updated_On")
    private LocalDateTime updatedOn;
    
    @Column(name = "approved_By")
    private Long approvedBy;
    
    @NotNull
    @Size(min = 1, max = 1, 
    message = "Approval status must be of 1 character.")
    @Column(name = "approval_Status")
    private String approvalStatus;

    @NotNull
    @Column(name = "active_Status")
    private boolean activeStatus;
    
    @Transient 
    private Company company;
}

@Entity
@Table(name = "tbl_Administrator")
public class Admin {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    private int adminId;
    
    @OneToOne()
    @JoinColumn(name = "user_Id")
    private User user;
    
    @OneToOne()
    @JoinColumn(name = "company_Id")
    private Company company;    
}

@Entity
@Table(name = "tbl_Distributor")
public class Distributor {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    private Long distributorId;
    
    @OneToOne()
    @JoinColumn(name = "user_Id")
    private User user;
    
    @ManyToOne()
    @JoinColumn(name = "company_Id")
    private Company company;
}

@Entity
@Table(name = "tbl_Retailer")
public class Retailer {

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

    @OneToOne()
    @JoinColumn(name = "user_Id")
    private User user;
}

CodePudding user response：

I would go with a @MappedSuperclass instead of making User and entity itself. Basically, Admin, Distributor and Retailer would extend this mapped superclass. A separate table for each is created but no table is created for the superclass (User) itself.

@MappedSuperclass
public class User {

   // Your properties
   
}

@Entity
@Table(name = "tbl_Administrator")
public class Admin extends User {

    @OneToOne()
    @JoinColumn(name = "company_Id")
    private Company company;  
     
}

@Entity
@Table(name = "tbl_Distributor")
public class Distributor extends User {
    
    @ManyToOne()
    @JoinColumn(name = "company_Id")
    private Company company;
    
}

@Entity
@Table(name = "tbl_Retailer")
public class Retailer extends User {

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

You have other possibilities (read more at https://medium.com/analytics-vidhya/jpa-hibernate-entity-inheritance-1f6aa7ea2eea), such as the following:

Single table for all entities
Separate tables for superclass and subclass. The properties defined in the superclass are not included in the tables of the subclass.
Table per class, which is similar to the Mapped Superclass with the difference that the Superclass also has a corresponding table.

Still, I would go with the Mapped Superclass one as described.