android-room

问题 So, I'm using Room database to store courses and I'm stuck on the method that returns the course with the name(course) that I want because it's always returning null. I have diminished my database to have 2 courses with the course variable as: As you can see in the picture above, when I try to get the CourseEnt in the Repository with course = fun , which I can see below that it exists, it returns a LiveData with a null value instead of the CourseEnt that I wanted. Any idea on what I'm doing

问题 It's possible for room to have Recursive relations? I have an Entity that can be nested in a Parent/Childs structures something like this Category1 |_________Category2 |_________Category3 | |_________Category4 |_________Category5` I'm copying this structure from a json that is obtained from a WebService. This is my current Entity: @Entity(tableName = "categories") public class Category { @PrimaryKey @NonNull private String code; private String name; private String parentCode; @Relation

问题 I have a Room database and RecyclerView that shows a list of CardViews. One of the database columns holds Sort Index values so the CardViews can easily be sorted and moved within the RecyclerView list. I have a Dao call to update the Sort Index values whenever a CardView is moved, deleted or added. Room requires CRUD on a background thread and the syntax I have in the AsyncTask() in the respository that calls the Dao method is wrong. I am trying to pass the individual "int" sortOrders and the

问题 I have an android service (no UI) with a class FooManager that needs to fetch all Foo objects (rows) in a database table foo using room and the androidx paging library. All examples I have found show how to do this using the PagedListAdapter and RecyclerView. Since I have no UI I cannot use view classes. Here is what I have tried: In my FooDao class I have the following method: @Query("SELECT * FROM foo") DataSource.Factory<Integer, Foo> getAllPaged(); In the constructor for my FooManager

问题 I noticed that I have to use kapt instead of annotationProcessor to make Dagger 2 work properly in my Kotlin project. Do I have to do the same to all the libraries (specifically Glide and Room )? 回答1: Yes, it is recommended to do so. The documentation stated: If you previously used the Android support for annotation processors, replace usages of the annotationProcessor configuration with kapt . If your project contains Java classes, kapt will also take care of them. Read more on Using kapt 来源

问题 I noticed that I have to use kapt instead of annotationProcessor to make Dagger 2 work properly in my Kotlin project. Do I have to do the same to all the libraries (specifically Glide and Room )? 回答1: Yes, it is recommended to do so. The documentation stated: If you previously used the Android support for annotation processors, replace usages of the annotationProcessor configuration with kapt . If your project contains Java classes, kapt will also take care of them. Read more on Using kapt 来源

问题 I'm playing with LiveData and want to understand what it can do. I want to fill my RecyclerView with data from different sources by switch(using filters if you like). Filtering values inside an adapter is not an option. So, I decided to use MediatorLiveData inside my view model. Dao: @Query("SELECT * FROM tasks WHERE completed = 0") LiveData<List<Task>> getActiveTasksLiveData(); @Query("SELECT * FROM tasks") LiveData<List<Task>> getAllTasksLiveData(); @Query("SELECT * FROM tasks WHERE

问题 I want to get Kotlin Coroutnies Deffered from DAO @Query("select * from gameprocess where cabinId = :cabinId ") fun getAllGameProccesBiCabin(cabinId :Int) : Deferred<GameProcess> but it does not compile (room does not know how to handle Deffered), but I need to use 'wait' from 'Deffered' how can do this? as another option I could use extension function from this post but, dont know how to integrate it into dao: https://codelabs.developers.google.com/codelabs/kotlin-coroutines/index.html?index

问题 I want to get Kotlin Coroutnies Deffered from DAO @Query("select * from gameprocess where cabinId = :cabinId ") fun getAllGameProccesBiCabin(cabinId :Int) : Deferred<GameProcess> but it does not compile (room does not know how to handle Deffered), but I need to use 'wait' from 'Deffered' how can do this? as another option I could use extension function from this post but, dont know how to integrate it into dao: https://codelabs.developers.google.com/codelabs/kotlin-coroutines/index.html?index

问题 So basically i am using room and trying to add migration from database version 1 to 2 but my alter command is not working My current implementation is below : void init() { db = Room.databaseBuilder(Global.getInstance(), AppDatabase.class, "feed").addMigrations(MIGRATION_1_2).build(); } Migration property : static final Migration MIGRATION_1_2 = new Migration(1,2) { @Override public void migrate(SupportSQLiteDatabase database) { database.execSQL("ALTER TABLE 'post' ADD COLUMN 'age' INTEGER