How to properly get table name in DAO class using Android Room

Question

I wonder how to avoid hard coding when using table name in Android Room query. I develop in Kotlin, but to be honest in this problem it doesn't matter is Java or Kotlin.

Let's see that simple classes:

DAO interface:

@Dao
interface UserDAO {

    @Query("SELECT * FROM USER")
    fun getAll(): List<User>
}

Entity class:

@Entity(tableName = "USER")
class User {
}

You can see that the table name "USER" is hard coded in @Query in UserDAO. How to avoid that? How to refer to @Entity parameter tableName?

I would like to have all names in one and only one place.

Answer 1

You can make a constant in any of Util classes and can refer that variable in Entity and Dao class like this:-

Suppose in MainActivity you have

    companion object {
        const val TABLE_NAME: String="Cheese"
    }

Entity class

@Entity(tableName = MainActivity.TABLE_NAME)

and Dao class will be

@Query("SELECT * FROM "+MainActivity.TABLE_NAME)

Note :- This is an usual approach to avoid hard coded naming may be you can get table name from Entity class(Needs to be explored) :) .