Marks a function in a Dao annotated class as a raw query function where the query is pass as a parameter of types androidx.room3.RoomRawQuery or androidx.sqlite.db.SupportSQLiteQuery.

@Dao
interface RawDao {
    @RawQuery
    suspend fun getSongViaQuery(query: RoomRawQuery): Song
}

// Usage of RawDao
val query = RoomRawQuery(
    sql = "SELECT * FROM Song WHERE id = ? LIMIT 1",
    onBindStatement = { it.bindLong(1, songId) }
)
val song = rawDao.getSongViaQuery(query)

Room will generate the code based on the return type of the function and failure to pass a proper query will result in a runtime failure or an undefined result.

If you know the query at compile time, you should always prefer Query since it validates the query at compile time and also generates more efficient code, since Room can compute the query result at compile time (e.g. it does not need to account for possibly missing columns in the result).

On the other hand, @RawQuery serves as an escape hatch where you can build your own SQL query at runtime but still use Room to convert it into objects.

@RawQuery functions must return a value and their return type should be a non-void / non-Unit type.

@RawQuery functions can only be used for read queries, using a write query will lead to undefined behavior. For write queries, use androidx.room3.RoomDatabase.useWriterConnection:

suspend fun executeRawQuery(query: RoomRawQuery) {
    db.useWriterConnection { connection ->
        connection.usePrepared(query.sql) { statement ->
            query.getBindingFunction().invoke(statement)
            statement.step()
        }
    }
}

Observable Queries:

@RawQuery functions can return observable types such as kotlinx.coroutines.flow.Flow but you need to specify which tables are accessed in the query using the observedEntities annotation value.

@Dao
interface RawDao {
    @RawQuery(observedEntities = Song::class)
    fun getSongs(query: RoomRawQuery): Flow<List<Song>>
}

// Usage of RawDao
val liveSongs = rawDao.getSongs(
    RoomRawQuery("SELECT * FROM song ORDER BY name DESC")
)

Returning Data Objects:

@RawQuery can also return data objects, similar to Query methods.

data class NameAndReleaseYear (
    val name: String,
    @ColumnInfo(name = "release_year")
    val year: Int
)

@Dao
interface RawDao {
    @RawQuery
    suspend fun getNameAndReleaseYear(query: RoomRawQuery): NameAndReleaseYear
}

// Usage of RawDao
val result: NameAndReleaseYear = rawDao.getNameAndReleaseYear(
    RoomRawQuery(
        sql = "SELECT * FROM song WHERE id = ?",
        onBindStatement = { it.bindLong(1, songId) }
    )
)

Data Objects with Embedded Properties:

@RawQuery methods can return data objects that include Embedded properties as well.

data class SongAndArtist (
    @Embedded
    val song: Song,
    @Embedded
    val artist: Artist
)

@Dao
interface RawDao {
    @RawQuery
    suspend fun getSongAndArtist(query: RoomRawQuery): SongAndArtist
}

// Usage of RawDao
val result: = rawDao.getSongAndArtist(
    RoomRawQuery("SELECT * FROM Song, Artist WHERE Song.artistId = Artist.id LIMIT 1")
)

Relations:

@RawQuery return types can also be objects with Relation.

data class AlbumAndSongs {
    @Embedded
    val album: Album,
    @Relation(parentColumn = "id", entityColumn = "albumId")
    val songs: List<Song>
}

@Dao
interface RawDao {
    @RawQuery
    suspend fun getAlbumAndSongs(query: RoomRawQuery): List<AlbumAndSongs>
}

// Usage of RawDao
val result = rawDao.getAlbumAndSongs(
    RoomRawQuery("SELECT * FROM album")
)

Summary

Public constructors
RawQuery(observedEntities: Array<KClass<*>>)
Cmn

Public properties
Array<KClass<*>>

Denotes the list of entities which are accessed in the provided query and should be observed for invalidation if the query is observable.
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Public constructors

RawQuery

Cmn 
RawQuery(observedEntities: Array<KClass<*>> = [])

Public properties

observedEntities

Cmn 
val observedEntities: Array<KClass<*>>

Denotes the list of entities which are accessed in the provided query and should be observed for invalidation if the query is observable.

The listed classes should either be annotated with Entity or they should reference at least one Entity (via Embedded or Relation).

Providing this value in a non-observable query has no impact.

@Dao
interface RawDao {
    @RawQuery(observedEntities = Song::class)
    suspend fun getSongs(query: RoomRawQuery): Flow<List<Song>>
}
val liveSongs: = rawDao.getSongs(
    RoomRawQuery("SELECT * FROM song ORDER BY name DESC")
)
Returns
Array<KClass<*>>

List of entities that should invalidate the query if changed.