javax.persistence

Annotation Type DiscriminatorColumn

@Target(value=TYPE)
@Retention(value=RUNTIME)
public @interface DiscriminatorColumn

Specifies the discriminator column for the SINGLE_TABLE and JOINED Inheritance mapping strategies.

The strategy and the discriminator column are only specified in the root of an entity class hierarchy or subhierarchy in which a different inheritance strategy is applied

If the DiscriminatorColumn annotation is missing, and a discriminator column is required, the name of the discriminator column defaults to "DTYPE" and the discriminator type to DiscriminatorType.STRING.

     Example:
 
     @Entity
     @Table(name="CUST")
     @Inheritance(strategy=SINGLE_TABLE)
     @DiscriminatorColumn(name="DISC", discriminatorType=STRING, length=20)
     public class Customer { ... }
 
     @Entity
     public class ValuedCustomer extends Customer { ... }
 

Since:

Java Persistence 1.0

See Also:

DiscriminatorValue

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
String	columnDefinition (Optional) The SQL fragment that is used when generating the DDL for the discriminator column.
DiscriminatorType	discriminatorType (Optional) The type of object/column to use as a class discriminator.
int	length (Optional) The column length for String-based discriminator types.
String	name (Optional) The name of column to be used for the discriminator.

Element Detail

columnDefinition

public abstract String columnDefinition

(Optional) The SQL fragment that is used when generating the DDL for the discriminator column.

Defaults to the provider-generated SQL to create a column of the specified discriminator type.

Default:

""

discriminatorType

public abstract DiscriminatorType discriminatorType

(Optional) The type of object/column to use as a class discriminator. Defaults to DiscriminatorType.STRING.

Default:

javax.persistence.DiscriminatorType.STRING

length

public abstract int length

(Optional) The column length for String-based discriminator types. Ignored for other discriminator types.

Default:

31

name

public abstract String name

(Optional) The name of column to be used for the discriminator.

Default:

"DTYPE"