PrimaryKey.kt
/*
* 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
/**
* Marks a field in an [Entity] as the primary key.
*
* If you would like to define a composite primary key, you should use [Entity.primaryKeys]
* method.
*
* Each [Entity] must declare a primary key unless one of its super classes declares a
* primary key. If both an [Entity] and its super class defines a [PrimaryKey], the
* child's [PrimaryKey] definition will override the parent's [PrimaryKey].
*
* If `PrimaryKey` annotation is used on a [Embedded] field, all columns inherited
* from that embedded field becomes the composite primary key (including its grand children
* fields).
*/
@Target(AnnotationTarget.FIELD, AnnotationTarget.FUNCTION)
@Retention(AnnotationRetention.BINARY)
public annotation class PrimaryKey(
/**
* Set to true to let SQLite generate the unique id.
*
* When set to `true`, the SQLite type affinity for the field should be `INTEGER`.
*
* If the field type is `Long` or `Int` (or its TypeConverter converts it to a
* `Long` or `Int`), [Insert] methods treat `0` as not-set while
* inserting the item.
*
* If the field's type is [Integer] or [Long] (or its TypeConverter converts it to
* an [Integer] or [Long]), [Insert] methods treat `null` as
* not-set while inserting the item.
*
* @return Whether the primary key should be auto-generated by SQLite or not. Defaults
* to false.
*/
val autoGenerate: Boolean = false
)