This is a common problem I’ve seen since Room was announced. Room does not support the ability to store Lists directly, nor the ability to convert to/from Lists. It supports converting and storing POJO’s. In this case the solution is simple. Instead of storing a List<CountryLang> you want to store CountryLangs (note the ‘s’) I’ve … Read more
Based on the documentation here (below the code snippet) A method annotated with the @Insert annotation can return: long for single insert operation long[] or Long[] or List<Long> for multiple insert operations void if you don’t care about the inserted id(s)
This is how I solved it, and how you can ship your application with a pre-populated database (up to Room v. alpha5) put your SQLite DB database_name.db into the assets/databases folder take the files from this repo and put them in a package called i.e. sqlAsset in your AppDatabase class, modify your Room’s DB creation … Read more
It’s not a problem in your case, but for others, this error can occur if you have @Ignore params in your primary constructor, i.e. Room expects to have either: parameterless constructor or constructor with all fields not marked with @Ignore for example: @Entity(tableName = “movies”) data class MovieKt( @PrimaryKey var id : Int, var title: … Read more
You can do this by changing your Dao from an interface to an abstract class. @Dao public abstract class UserDao { public void insertPetsForUser(User user, List<Pet> pets){ for(Pet pet : pets){ pet.setUserId(user.getId()); } _insertAll(pets); } @Insert abstract void _insertAll(List<Pet> pets); //this could go in a PetDao instead… @Insert public abstract void insertUser(User user); @Query(“SELECT * … Read more
For those working with Kotlin, try changing annotationProcessor to kapt in the apps build.gradle for example: // Extensions = ViewModel + LiveData implementation “android.arch.lifecycle:extensions:1.1.0” kapt “android.arch.lifecycle:compiler:1.1.0” // Room implementation “android.arch.persistence.room:runtime:1.0.0” kapt “android.arch.persistence.room:compiler:1.0.0” also remember to add this plugin apply plugin: ‘kotlin-kapt’ to the top of the app level build.gradle file and do a clean and … Read more
Type Converter are made specifically for that. In your case, you can use code snippet given below to store data in DB. public class Converters { @TypeConverter public static ArrayList<String> fromString(String value) { Type listType = new TypeToken<ArrayList<String>>() {}.getType(); return new Gson().fromJson(value, listType); } @TypeConverter public static String fromArrayList(ArrayList<String> list) { Gson gson = new … Read more
Document is really confusing. Try with just below classes: 1) User Entity: @Entity public class User { @PrimaryKey public int id; // User id } 2) Pet Entity: @Entity public class Pet { @PrimaryKey public int id; // Pet id public int userId; // User id public String name; } 3) UserWithPets POJO: // Note: … Read more
It’s not recommended but you can access to database on main thread with allowMainThreadQueries() MyApp.database = Room.databaseBuilder(this, AppDatabase::class.java, “MyDatabase”).allowMainThreadQueries().build()
Yes, you can. You can call Kotlin function with Java and you also can call Java function with Kotlin. But you must write kotlin code in .kt file and write Java code in .java file.