com.speedment.runtime.field.method.FindFrom Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of runtime-field Show documentation

Partly generated model of the fields that represent columns in the database. Fields can be used to produce special predicates and functions that contain metadata that Speedment can analyze runtime.

There is a newer version: 3.2.10

Show newest version

/**
 *
 * Copyright (c) 2006-2017, Speedment, Inc. All Rights Reserved.
 *
 * Licensed 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 "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.speedment.runtime.field.method;

import com.speedment.runtime.config.identifier.TableIdentifier;
import com.speedment.runtime.field.Field;

import java.util.function.Function;

/**
 * A handle for a find-operation that can be replaced runtime to optimize a 
 * {@code Stream}. Formally, a {@code FindFrom} has the following signature:
 * {@code
 *      FK_ENTITY apply(ENTITY entity);
 * }
 * 
 * Each {@code FindFrom} contains metadata of which fields it compares to 
 * determine the mapping as well as a reference to the foreign manager.
 * 
 * @param      the source entity
 * @param   the target entity
 * 
 * @author Emil Forslund
 * @since  3.0.0
 */
public interface FindFrom extends Function {
    
    /**
     * Returns the field that the stream originates from. 
     * 

     * In the following example, {@code foo} is the source:
     * {@code
     *      foos.stream()
     *          .flatMap(foo.findBars()) // findBars returns Streamer
     *          .forEach(...);
     * }
     * 
     * @return  the source field
     */
    Field getSourceField();
    
    /**
     * Returns the field that the stream references. 
     * 
     * In the following example, {@code bar} is the target:
     * {@code
     *      foos.stream()
     *          .flatMap(foo.findBars()) // findBars returns Streamer
     *          .forEach(...);
     * }
     * 
     * @return  the target field
     */
    Field getTargetField();
    
    /**
     * Returns the identifier for the referenced (foreign) table.
     * 
     * @return  target (foreign) table identifier
     */
    TableIdentifier getTableIdentifier();

}