JPA, How to use the same class (entity) to map different tables?

java jpa entity
John picture John · Jun 15, 2009 · Viewed 36.4k times · Source

I have two tables: Ta and Tb. They have exactly the same table structure but different table names.

I try to create one entity class to map the table structures. Some of my common application modules will use this entity class to dynamically query and update either Ta or Tb based on parameters. Can it be done in JPA? How can I write the program to dynamically mapping the entity class to different tables at run time?

Answer

Glen picture Glen · Jun 15, 2009

Not sure you can do it exactly as you want but you can use inheritance to produce the same result.

AbsT has all the fields but no @Table annotation

Ta and Tb inherit from AbsT and have an @Table annotation each

Use 

@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)

in AbsT.

Sample code:

@Entity
@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)
public class abstract AbsT {
    @Id Long id;
...
}

@Entity
@Table(name = "Ta")
public class Ta extends AbsT {
...
}

@Entity
@Table(name = "Tb")
public class Tb extends AbsT {
...
}

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