org.apache.openjpa.jdbc.meta.ValueHandler Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
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* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
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package org.apache.openjpa.jdbc.meta;
import java.io.Serializable;
import java.sql.SQLException;
import org.apache.openjpa.jdbc.kernel.JDBCFetchConfiguration;
import org.apache.openjpa.jdbc.kernel.JDBCStore;
import org.apache.openjpa.jdbc.schema.Column;
import org.apache.openjpa.jdbc.schema.ColumnIO;
import org.apache.openjpa.jdbc.sql.Result;
import org.apache.openjpa.kernel.OpenJPAStateManager;
/**
* Maps a value to a relational schema. Value handler are stateless.
*
* @author Abe White
* @since 0.4.0
*/
public interface ValueHandler
extends Serializable {
/**
* Map the given value and return all mapped columns, or simply return an
* array of unmapped default columns. The columns should have at least
* their Name and JavaType properties set.
*
* @param name use as a base to form column name(s); the column names
* of unmapped columns will automatically be made to fit
* database limitations
* @param io I/O information about mapped columns; you do not
* have to set this information if returning templates
* @param adapt whether to adapt the mapping or schema
*/
Column[] map(ValueMapping vm, String name, ColumnIO io,
boolean adapt);
/**
* Return whether the values managed by this handler can be used in
* state image versioning.
*/
boolean isVersionable(ValueMapping vm);
/**
* Return whether this handler potentially must load extra data to extract
* the object value from its datastore representation.
*/
boolean objectValueRequiresLoad(ValueMapping vm);
/**
* Return the argument to pass to the result set when loading data
* via {@link Result#getObject}, or null if none. If this value
* occupies multiple columns, return an array with one element per
* column. You may return null if all array elements would be null.
*/
Object getResultArgument(ValueMapping vm);
/**
* Translate the given value to its datastore equivalent. If this value
* occupies multiple columns, return an object array with one element
* per column. For relation id columns, return the state manager
* the column depends on.
*/
Object toDataStoreValue(ValueMapping vm, Object val,
JDBCStore store);
/**
* Translate the given datastore value into its Java equivalent. If
* the value occupies multiple columns, the given object will be an object
* array with one entry per column. This method is only called if
* {@link #objectValueRequiresLoad} returns false.
*/
Object toObjectValue(ValueMapping vm, Object val);
/**
* Translate the given datastore value into its Java equivalent. If
* the value occupies multiple columns, the given object will be an object
* array with one entry per column. This method is only called if
* {@link #objectValueRequiresLoad} returns true.
*
* @param sm the state manager that owns the value; may be null if
* loading a projection
*/
Object toObjectValue(ValueMapping vm, Object val,
OpenJPAStateManager sm, JDBCStore store, JDBCFetchConfiguration fetch)
throws SQLException;
}