android - 如何在房间中自动增加主键？

Question

data class FavouriteEntity(
    @PrimaryKey(autoGenerate = true)
    val id : Int?,
    @ColumnInfo(name = "user_id") var userId : String,
    @ColumnInfo(name = "fav_restaurant_id") var favouriteRestaurantId : String,
    @ColumnInfo(name = "fav_restaurant_name") var favouriteRestaurantName : String,
    @ColumnInfo(name = "fav_restaurant_img") var favouriteRestaurantImage : String,
    @ColumnInfo(name = "fav_restaurant_price") var favouriteRestaurantPrice : String,
    @ColumnInfo(name = "fav_restaurant_rating") var favouriteRestaurantRating : String
)

上面的类是我的实体类。我希望主键自动递增。
但是当我创建一个类的对象时:

var favouriteEntity = FavouriteEntity(

            userId,
            restaurant.restaurantId,
            restaurant.restaurantName,
            restaurant.restaurantImageUrl,
            restaurant.restaurantCostForOne,
            restaurant.restaurantRating
        )

我需要传递一个整数作为 id。但我想自动递增。请帮忙。

Answer 1

您可以简单地:

data class FavouriteEntity(
    @PrimaryKey(autoGenerate = true)
    val id : Int = 0 
)

或者

data class FavouriteEntity(
    @PrimaryKey(autoGenerate = true)
    val id : Int? = null 
)

并且 id 字段将自动生成/自动递增 id field 。
然后将其与命名参数一起使用:例如

data class FavouriteEntity(
        val id: Int = 0,
        val name: String
)

fun main() {
    FavouriteEntity(name = "name")
}