space.lingu.light.Relation Maven / Gradle / Ivy
/*
* Copyright (C) 2022 Lingu Light Project
*
* 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 space.lingu.light;
import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* Not available yet.
*
* @author RollW
*/
@Documented
@Target({})// TODO
@Retention(RetentionPolicy.RUNTIME)
@LightExperimentalApi
public @interface Relation {
/**
* The entity or view to fetch the item from. You don't need to set this if the entity or view
* matches the type argument in the return type.
*
* @return The entity or view to fetch from. By default, inherited from the return type.
*/
Class entity() default Object.class;
/**
* Reference column in the parent POJO.
*
* In a one-to-one or one-to-many relation, this value will be matched against the column
* defined in {@link #entityColumn()}. In a many-to-many using {@link #associateBy()} then
* this value will be matched against the {@link Junction#parentColumn()}
*
* @return The column reference in the parent object.
*/
String parentColumn();
/**
* The column to match in the {@link #entity()}.
*
* In a one-to-one or one-to-many relation, this value will be matched against the column
* defined in {@link #parentColumn()} ()}. In a many-to-many using {@link #associateBy()} then
* this value will be matched against the {@link Junction#entityColumn()}
*/
String entityColumn();
/**
* The entity or view to be used as a associative table (also known as a junction table) when
* fetching the relating entities.
*
* @return The junction describing the associative table. By default, no junction is specified
* and none will be used.
*
* @see Junction
*/
Junction associateBy() default @Junction(Object.class);
/**
* If sub columns should be fetched from the entity, you can specify them using this field.
*
* By default, inferred from the return type.
*
* @return The list of columns to be selected from the {@link #entity()}.
*/
String[] projection() default {};
}