io.ebean.annotation

Annotation Type DbForeignKey

@Retention(value=RUNTIME)
 @Target(value=FIELD)
public @interface DbForeignKey

Specify how a foreign key constraint should be defined.

We can specify if a constraint should not be defined at all or control the onDelete and onUpdate modes used.

Example: On delete cascade

@DbForeignKey(onDelete = ConstraintMode.CASCADE)
@ManyToOne
RelatedBean parent;

Example: No foreign key

// No FK Constraint
@DbForeignKey(noConstraint=true)
@ManyToOne
RelatedBean parent;

Example: On delete set null

@DbForeignKey(onDelete = ConstraintMode.SET_NULL)
@ManyToOne
RelatedBean parent;

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
boolean	noConstraint Set to true when we do not wish any foreign key constraint to be created.
boolean	noIndex Set to true when we do not wish an index to be created on the foreign key column(s).
ConstraintMode	onDelete Specify the onDelete mode.
ConstraintMode	onUpdate Do NOT change this - seriously, don't do it.

Element Detail

onDelete

public abstract ConstraintMode onDelete

Specify the onDelete mode. Typically will default to RESTRICT (aka No Action).

Default:

io.ebean.annotation.ConstraintMode.RESTRICT

onUpdate

public abstract ConstraintMode onUpdate

Do NOT change this - seriously, don't do it.

Your primary keys should never change by design. We should orientate the design to support primary keys that change (and instead find better non mutating primary keys). Oracle go to the point of actively not supporting "on update" for this reason.

So yes, we can specify the onUpdate mode but I don't expect anyone to change this.

Default:

io.ebean.annotation.ConstraintMode.RESTRICT

noConstraint

public abstract boolean noConstraint

Set to true when we do not wish any foreign key constraint to be created. When this is set to true the onDelete and onUpdate have no effect.

Default:

false

noIndex

public abstract boolean noIndex

Set to true when we do not wish an index to be created on the foreign key column(s).

Default:

false