Android Room @Delete with parameters

user_7480451 0
Viewed 115481

I know I can't use DELETE in a query (that is a shame by the way), I will get the following error:

<i>Error:error: Observable query return type (LiveData, Flowable etc) can only be used with SELECT queries that directly or indirectly (via @Relation, for example) access at least one table.</i>

But I can't use @Delete(WHERE... xxx) So how do I delete a specific row by a parameter?

android-room android sql java
5 Answers

You can use below method to delete by ID

@Query("DELETE FROM yourDatabaseTable WHERE id = :id")
void deleteById(int id);

for delete all rows

@Query("DELETE FROM yourDatabaseTable")
void delete();
user_69307190

ROOM database provides easy way to INSERT, UPDATE and DELETE an object in the database. To perform thus operation just needed to annotate @Delete. The DELETE operation returns the Int when deletion of the single object is successful returns 1 else returns 0 if the DELETE operation is unsuccessful, Adding the return type is a good practice.

KotlinEG.kt

   @Dao
   interface EntityLocalDAO {
       @Delete
       fun deleteData(entityObject: EntityObject) : Int
   }

javaEG.java

   @Dao
   interface EntityLocalDAO {
       @Delete
       int deleteData(EntityObject entityObject);
   }
user_138974050

You can now delete using only partial data.

Per the documentation:

@Entity
data class Playlist (
    @PrimaryKey
    val playlistId: Long,
    val ownerId: Long,
    val name: String,
    @ColumnInfo(defaultValue = "normal")
    val category: String
)

data class OwnerIdAndCategory (
    val ownerId: Long,
    val category: String
)

@Dao
public interface PlaylistDao {
    @Delete(entity = Playlist::class)
    fun deleteByOwnerIdAndCategory(varargs idCategory: OwnerIdAndCategory)
}

In this example you can see that they are deleting the Playlist using only the ownerId and the category. You do not even need to use the primary key (playlistId).

The key is to use the @Delete(entity = Playlist::class) annotation.

user_16795710
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