CODEWITHSUNDEEP
javahibernatejpa
Ilya
Ilya

Reputation: 29673

Mapping two classes on Single Table

Let's I have table

USER
-id : long
-login : varchar
-weapon: varchar
-magic: varchar

And I want map this Table on two classes (using Hibernate/JPA) 

class Mag  
{   
   long id;  
   String login;  
   String weapon;  
}

and 

class Warrior  
{  
   long id;  
   String login;  
   String magic;  
}

And if I send HQL query : SELECT m FROM Mag m WHERE m.login = ? then I get Mag instance
and if I send HQL query : SELECT w FROM Warrior w WHERE w.login = ? then I get Warrior instance
I try make something like this 

@Entity  
@Table(name = "User")  
class User   
{  
   long id;  
   String login;  
}  

@Entity  
class Mag extends User  
{  
   String magic;  
}  

@Entity  
class Warrior extends User   
{  
   String weapon;  
}

But @Inheritance requared discriminator column, but I haven't discriminator.

Upvotes: 5

Views: 6851

Answers (2)

Dinusha
Dinusha

Reputation: 716

You can use the Discriminator for this,if you have a deliminator column. Assume you deliminator column is

utype char(1)

And if

utype = m, that is a Mag entity and

utype=w, that is Warrior entity

Please find code bellow. 

@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "utype", discriminatorType =  DiscriminatorType.CHAR)
@Table(name = "User")  
class User   
{  
   long id;  
   String login;  
}  

@Entity
@DiscriminatorValue("m")  
class Mag extends User  
{  
   String magic;  
}  

@Entity  
@DiscriminatorValue("w")  
class Warrior extends User   
{  
   String weapon;  
}

Upvotes: 2

beerbajay
beerbajay

Reputation: 20270

You're looking for MappedSuperClass, which allows the subclasses to inherit the annotations from the superclass without needing a discriminator.

Upvotes: 8

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