Package org.datanucleus.metadata

Class ForeignKeyMetaData

  • All Implemented Interfaces:
    Serializable
    public class ForeignKeyMetaData
extends ConstraintMetaData
    Foreign keys in metadata serve two quite different purposes. First, when generating schema, the foreign key element identifies foreign keys to be generated. Second, when using the database, foreign key elements identify foreign keys that are assumed to exist in the database. This is important for the runtime to properly order insert, update, and delete statements to avoid constraint violations. A foreign-key element can be contained by a field, element, key, value, or join element, if all of the columns mapped are to be part of the same foreign key. A foreign-key element can be contained within a class element. In this case, the column elements are mapped elsewhere, and the column elements contained in the foreign-key element have only the column name.
    See Also:
    Serialized Form

    • Field Detail

      • columns

        protected List<ColumnMetaData> columns
        The columns for this foreign key. Note that we don't use the "columnNames" in the superclass since the user can define the column target name also for a foreign-key.

      • unique

        protected boolean unique
        The unique attribute specifies whether the foreign key constraint is defined to be a unique constraint as well. This is most often used with one-to-one mappings.

      • deferred

        protected boolean deferred
        The deferred attribute specifies whether the foreign key constraint is defined to be checked only at commit time.

      • deleteAction

        protected ForeignKeyAction deleteAction
        Foreign keys represent a consistency constraint in the database that must be maintained. The user can specify by the value of the delete-action attribute what happens if the target row of a foreign key is deleted.

      • updateAction

        protected ForeignKeyAction updateAction
        Foreign keys represent a consistency constraint in the database that must be maintained. The user can specify by the update-action attribute what happens if the target row of a foreign key is updated.

      • fkDefinition

        protected String fkDefinition
        Alternative method of specifying FK where we just supply the string defining it (JPA crap).

      • fkDefinitionApplies

        protected boolean fkDefinitionApplies

    • Constructor Detail

      • ForeignKeyMetaData

        public ForeignKeyMetaData()

      • ForeignKeyMetaData

        public ForeignKeyMetaData​(ForeignKeyMetaData fkmd)
        Copy constructor.
        Parameters:
        fkmd - The metadata to copy

    • Method Detail

      • newColumnMetaData

        public ColumnMetaData newColumnMetaData()
        Method to create a new column, add it, and return it.
        Returns:
        The column metadata

      • getColumnMetaData

        public final ColumnMetaData[] getColumnMetaData()

      • isDeferred

        public final boolean isDeferred()

      • setDeleteAction

        public void setDeleteAction​(ForeignKeyAction deleteAction)

      • isUnique

        public final boolean isUnique()

      • setFkDefinition

        public void setFkDefinition​(String def)

      • getFkDefinition

        public String getFkDefinition()

      • setFkDefinitionApplies

        public void setFkDefinitionApplies​(boolean flag)

      • getFkDefinitionApplies

        public boolean getFkDefinitionApplies()