1 /*
2  * Copyright (C) 2017 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package androidx.room
17 
18 import kotlin.reflect.KClass
19 
20 /**
21  * Marks a method in a [Dao] annotated class as an update method.
22  *
23  * The implementation of the method will update its parameters in the database if they already
24  * exists (checked by primary keys). If they don't already exists, this option will not change the
25  * database.
26  *
27  * All of the parameters of the Update method must either be classes annotated with [Entity] or
28  * collections/array of it.
29  *
30  * Example:
31  * ```
32  * @Dao
33  * public interface MusicDao {
34  *     @Update
35  *     fun updateSong(song: Song)
36  *
37  *     @Update
38  *     fun updateSongs(songs: List<Song>): Int
39  * }
40  * ```
41  *
42  * If the target entity is specified via [entity] then the parameters can be of arbitrary POJO types
43  * that will be interpreted as partial entities. For example:
44  * ```
45  * @Entity
46  * data class Playlist (
47  *     @PrimaryKey(autoGenerate = true)
48  *     val playlistId: Long,
49  *     val name: String,
50  *     @ColumnInfo(defaultValue = "")
51  *     val description: String,
52  *     @ColumnInfo(defaultValue = "normal")
53  *     val category: String,
54  *     @ColumnInfo(defaultValue = "CURRENT_TIMESTAMP")
55  *     val createdTime: String,
56  *     @ColumnInfo(defaultValue = "CURRENT_TIMESTAMP")
57  *     val lastModifiedTime: String
58  * )
59  *
60  * data class PlaylistCategory (
61  *   val playlistId: Long,
62  *   val category: String,
63  *   val lastModifiedTime: String
64  * )
65  *
66  * @Dao
67  * public interface PlaylistDao {
68  *   @Update(entity = Playlist::class)
69  *   fun updateCategory(varargs category: Category)
70  * }
71  * ```
72  *
73  * @see [Insert]
74  * @see [Delete]
75  */
76 @Target(AnnotationTarget.FUNCTION)
77 @Retention(AnnotationRetention.BINARY)
78 public annotation class Update(
79 
80     /**
81      * The target entity of the update method.
82      *
83      * When this is declared, the update method parameters are interpreted as partial entities when
84      * the type of the parameter differs from the target. The POJO class that represents the entity
85      * must contain a subset of the fields of the target entity along with its primary keys.
86      *
87      * Only the columns represented by the partial entity fields will be updated if an entity with
88      * equal primary key is found.
89      *
90      * By default the target entity is interpreted by the method parameters.
91      *
92      * @return the target entity of the update method or none if the method should use the parameter
93      *   type entities.
94      */
95     val entity: KClass<*> = Any::class,
96 
97     /**
98      * What to do if a conflict happens.
99      *
100      * Use [OnConflictStrategy.ABORT] (default) to roll back the transaction on conflict. Use
101      * [OnConflictStrategy.REPLACE] to replace the existing rows with the new rows. Use
102      * [OnConflictStrategy.IGNORE] to keep the existing rows.
103      *
104      * @return How to handle conflicts. Defaults to [OnConflictStrategy.ABORT].
105      */
106     @get:OnConflictStrategy val onConflict: Int = OnConflictStrategy.ABORT
107 )
108