ROOM.md

Room

Table of Contents

1. Gradle Dependency
2. Using @Transaction
3. Custom 'id' column name

---

Gradle Dependency

The Room module contains some base classes that will enable you to use a standarized way of working with Entities and Daos

dependencies {
  ...
  implementation 'com.github.appwise-labs.AndroidCore:room:<Latest-Version>'

  kapt "androidx.room:room-compiler:<Latest-Room-Version>"
}

---

Using @Transaction

In case you wish to use @Transaction in combination with AndroidCore's BaseRoomDao, you should use an open keyword with your function.

@Dao
abstract class Dao: BaseRoomDao<Item>("item"){

    @Insert
    abstract fun insert(item: Item)

    @Delete
    abstract fun delete(item: Item)

    @Transaction
    open fun replace(oldItem: Item, newItem: Item){
        delete(oldItem)
        insert(newItem)
    }
}

In case you omit the open keyword you'll get an error error: Method annotated with @Transaction must not be private, final, or abstract.

---

Custom 'id' column name

When using BaseEntity and you wish to provide a different name for the id column, you can do so by using the @ColumnInfo on your Entity. Doing this, however, breaks the standard use of our BaseDao class. For it to work, just overridde the idColumnInfo in your Dao to tie it together.

override val idColumnInfo = DBConstants.COLUMN_ID_USER

I suggest to use a class to put all your Database constants in, i.e.:

object DBConstants {
    const val DATABASE_NAME = "poemCollection.db"
    const val USER_TABLE_NAME = "user"

    const val COLUMN_ID_USER = "userId"
}

Another possibility is to add the constants in a companion object in the classes where the constants are needed in.

Doing either of this will enable you to provide your table and column names in queries like so:

@Query("SELECT * FROM ${DBConstants.POEM_TABLE_NAME} WHERE ${DBConstants.COLUMN_ID_POEM} = :poemId")

Should you ever need to change those values, then you'd only have to do so in one location.