org.apache.openjpa.jdbc.meta.Joinable Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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*
* http://www.apache.org/licenses/LICENSE-2.0
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*/
package org.apache.openjpa.jdbc.meta;
import java.io.Serializable;
import java.sql.SQLException;
import org.apache.openjpa.jdbc.kernel.JDBCStore;
import org.apache.openjpa.jdbc.schema.Column;
import org.apache.openjpa.jdbc.schema.ForeignKey;
import org.apache.openjpa.jdbc.sql.Joins;
import org.apache.openjpa.jdbc.sql.Result;
import org.apache.openjpa.kernel.OpenJPAStateManager;
/**
* Represents a value that can be joined to. Any column that a user
* joins to must be "owned" by an entity that implements this interface.
* The system maps columns to joinables to be able to decompose oids and
* field values into individual join values on a per-column basis. This
* allows us to support joins to only some of the columns of a mapping, and
* to be loose with the ordering of foreign key columns relative to the
* ordering of the joined-to columns. Having a separate interface for
* joinables also allows us to perform tricks such as a vertically-mapped
* application identity subclass transparently transforming columns of its
* foreign key to the corresponding primary key fields in the base class.
*
* @author Abe White
*/
public interface Joinable
extends Serializable {
/**
* Return the field index of this joinable, or -1 if not a field.
*/
public int getFieldIndex();
/**
* Return the value for this joinable from the given result, using the
* given columns. If the given foreign key is non-null, use the foreign
* key's columns by translating the given columns through
* {@link ForeignKey#getColumn}.
*/
public Object getPrimaryKeyValue(Result res, Column[] cols, ForeignKey fk,
JDBCStore store, Joins joins)
throws SQLException;
/**
* The columns managed by this joinable.
*/
public Column[] getColumns();
/**
* Return the join value of the given column.
*
* @param val the value of the field for this joinable
* @param col the column of this joinable whose value to return
*/
public Object getJoinValue(Object val, Column col, JDBCStore store);
/**
* Return the join value of the given column.
*
* @param sm the instance from which to get the value
* @param col the column whose value to return
*/
public Object getJoinValue(OpenJPAStateManager sm, Column col,
JDBCStore store);
/**
* Use the given auto-assigned value to set this join value's field
* on the given instance.
*/
public void setAutoAssignedValue(OpenJPAStateManager sm, JDBCStore store,
Column col, Object autogen);
}