Delete.java
/*
* Copyright (C) 2016 The Android Open Source 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 androidx.room;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* Marks a method in a {@link Dao} annotated class as a delete method.
* <p>
* The implementation of the method will delete its parameters from the database.
* <p>
* All of the parameters of the Delete method must either be classes annotated with {@link Entity}
* or collections/array of it.
* <p>
* Example:
* <pre>
* {@literal @}Dao
* public interface MusicDao {
* {@literal @}Delete
* public void deleteSongs(Song... songs);
*
* {@literal @}Delete
* public void deleteAlbumAndSongs(Album album, List<Song> songs);
* }
* </pre>
* If the target entity is specified via {@link #entity()} then the parameters can be of arbitrary
* POJO types that will be interpreted as partial entities. For example:
* <pre>
* {@literal @}Entity
* public class Playlist {
* {@literal @}PrimaryKey
* long playlistId;
* long ownerId;
* String name;
* {@literal @}ColumnInfo(defaultValue = "normal")
* String category;
* }
*
* public class OwnerIdAndCategory {
* long ownerId;
* String category;
* }
*
* {@literal @}Dao
* public interface PlaylistDao {
* {@literal @}Delete(entity = Playlist.class)
* public void deleteByOwnerIdAndCategory(OwnerIdAndCategory... idCategory);
* }
* </pre>
*
* @see Insert
* @see Update
*/
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.CLASS)
public @interface Delete {
/**
* The target entity of the delete method.
* <p>
* When this is declared, the delete method parameters are interpreted as partial entities when
* the type of the parameter differs from the target. The POJO class that represents the entity
* must contain a subset of the fields of the target entity. The fields value will be used to
* find matching entities to delete.
* <p>
* By default the target entity is interpreted by the method parameters.
*
* @return the target entity of the delete method or none if the method should use the
* parameter type entities.
*/
Class<?> entity() default Object.class;
}