Update.kt
/*
* Copyright (C) 2017 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 kotlin.reflect.KClass
/**
* Marks a method in a [Dao] annotated class as an update method.
*
* The implementation of the method will update its parameters in the database if they already
* exists (checked by primary keys). If they don't already exists, this option will not change the
* database.
*
* All of the parameters of the Update method must either be classes annotated with [Entity]
* or collections/array of it.
*
* Example:
*
* ```
* @Dao
* public interface MusicDao {
* @Update
* fun updateSong(song: Song)
*
* @Update
* fun updateSongs(songs: List<Song>): Int
* }
* ```
*
* If the target entity is specified via [entity] then the parameters can be of arbitrary
* POJO types that will be interpreted as partial entities. For example:
*
* ```
* @Entity
* data class Playlist (
* @PrimaryKey(autoGenerate = true)
* val playlistId: Long,
* val name: String,
* @ColumnInfo(defaultValue = "")
* val description: String,
* @ColumnInfo(defaultValue = "normal")
* val category: String,
* @ColumnInfo(defaultValue = "CURRENT_TIMESTAMP")
* val createdTime: String,
* @ColumnInfo(defaultValue = "CURRENT_TIMESTAMP")
* val lastModifiedTime: String
* )
*
* data class PlaylistCategory (
* val playlistId: Long,
* val category: String,
* val lastModifiedTime: String
* )
*
* @Dao
* public interface PlaylistDao {
* @Update(entity = Playlist::class)
* fun updateCategory(varargs category: Category)
* }
* ```
*
* @see [Insert]
* @see [Delete]
*/
@Target(AnnotationTarget.FUNCTION)
@Retention(AnnotationRetention.BINARY)
public annotation class Update(
/**
* The target entity of the update method.
*
* When this is declared, the update 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 along with its primary keys.
*
* Only the columns represented by the partial entity fields will be updated if an entity with
* equal primary key is found.
*
* By default the target entity is interpreted by the method parameters.
*
* @return the target entity of the update method or none if the method should use the
* parameter type entities.
*/
val entity: KClass<*> = Any::class,
/**
* What to do if a conflict happens.
*
* Use [OnConflictStrategy.ABORT] (default) to roll back the transaction on conflict.
* Use [OnConflictStrategy.REPLACE] to replace the existing rows with the new rows.
* Use [OnConflictStrategy.IGNORE] to keep the existing rows.
*
* @return How to handle conflicts. Defaults to [OnConflictStrategy.ABORT].
*/
@get:OnConflictStrategy
val onConflict: Int = OnConflictStrategy.ABORT
)