This is the way to provide the annotation you’re looking for, with explicit arrays for the arguments, and no @ for the nested annotation’s creation: @Entity(tableName = “Foo”, foreignKeys = arrayOf( ForeignKey(entity = Bar::class, parentColumns = arrayOf(“someCol”), childColumns = arrayOf(“someOtherCol”), onDelete = CASCADE))) Since Kotlin 1.2, you can also use array literals: @Entity(tableName = “Foo”, … Read more
It is usually not recommended to store image data into the database. But however if it is required for your project then you can do so. Image data are usually stored into db using BLOB data type, Room also provide support for BLOB data type Documentation You can declare your entity class as mentioned below … Read more
You’re converting from Date to Long (wrapper) and from long (primitive) to Date. I changed it to Long and it compiled. Besides, unboxing null in your converter produces a NPE. public class DateConverter { @TypeConverter public static Date toDate(Long dateLong){ return dateLong == null ? null: new Date(dateLong); } @TypeConverter public static Long fromDate(Date date){ … Read more
You can make a convert to each enum, like this: class Converters { @TypeConverter fun toHealth(value: String) = enumValueOf<Health>(value) @TypeConverter fun fromHealth(value: Health) = value.name } Or if you prefer store it as SQL integer, you can use ordinal too: class Converters { @TypeConverter fun toHealth(value: Int) = enumValues<Health>()[value] @TypeConverter fun fromHealth(value: Health) = value.ordinal … Read more
If you don’t want to provide migrations and you specifically want your database to be cleared when you upgrade the version, call fallbackToDestructiveMigration in the database builder database = Room.databaseBuilder(context.getApplicationContext(), UsersDatabase.class, “Sample.db”) .fallbackToDestructiveMigration() .build();
I find Room Relations hard to work with, not very flexible and much of the work is done under the hood in a way that is hard to really be sure how. In my projects, most of the time I just create presentation objects – objects dedicated for some UI presentation that can be filled … Read more
It’s possible to find the dependencies on the example codelab for the new architecture components. Root : allprojects { repositories { jcenter() maven { url “https://maven.google.com” } } For Room: implementation ‘android.arch.persistence.room:runtime:1.0.0-alpha1’ annotationProcessor ‘android.arch.persistence.room:compiler:1.0.0-alpha1’ For Lifecycle dependencies: implementation ‘android.arch.lifecycle:extensions:1.0.0-alpha1’ annotationProcessor ‘android.arch.lifecycle:compiler:1.0.0-alpha1’ Adding Rxjava2 objects as result for our queries: implementation ‘android.arch.persistence.room:rxjava2:1.0.0-alpha1′ Test migrations: testImplementation’android.arch.persistence.room:testing:1.0.0-alpha1’
Room supports @RawQuery annotation to construct queries at run-time. Step 1 : Make DAO method Mark the DAO method with @RawQuery annotation instead of normal @Query. @Dao interface BooksDao{ @RawQuery List<Book> getBooks(SupportSQLiteQuery query); } Step 2 : Construct the query Room uses prepared statements for security and compile time verification. Therefore, while constructing queries, we … Read more
When in kotlin code: Before @ColumnInfo(name = “question_id”) var questionId: Long After @ColumnInfo(name = “question_id”, index = true) //just add index = true var questionId: Long
You can use my helper method: val profile = MutableLiveData<ProfileData>() val user = MutableLiveData<CurrentUser>() val title = profile.combineWith(user) { profile, user -> “${profile.job} ${user.name}” } fun <T, K, R> LiveData<T>.combineWith( liveData: LiveData<K>, block: (T?, K?) -> R ): LiveData<R> { val result = MediatorLiveData<R>() result.addSource(this) { result.value = block(this.value, liveData.value) } result.addSource(liveData) { result.value = … Read more