android-room

问题 How do I make a single row query with Android Room with RxJava? I am able to query for List of items, no issues. Here, I want to find if a specific row exists. According to the docs, looks like I can return Single and check for EmptyResultSetException exception if no row exists. I can have something like: @Query("SELECT * FROM Users WHERE userId = :id LIMIT 1") Single<User> findByUserId(String userId); How do I use this call? Looks like there is some onError / onSuccess but cannot find those

问题 How do I make a single row query with Android Room with RxJava? I am able to query for List of items, no issues. Here, I want to find if a specific row exists. According to the docs, looks like I can return Single and check for EmptyResultSetException exception if no row exists. I can have something like: @Query("SELECT * FROM Users WHERE userId = :id LIMIT 1") Single<User> findByUserId(String userId); How do I use this call? Looks like there is some onError / onSuccess but cannot find those

问题 According to https://developer.android.com/training/data-storage/room/relationships We can have one-to-many relationships public class UserWithPlaylists { @Embedded public User user; @Relation( parentColumn = "userId", entityColumn = "userCreatorId" ) public List<Playlist> playlists; } @Transaction @Query("SELECT * FROM User") public List<UserWithPlaylists> getUsersWithPlaylists(); In both entity User and Playlist , we have added a column named sort_key The purpose is, when we perform query,

问题 In my app firstly i am fetching data from server using retrofit then it's saved in room database table then it shows in recyclerview but when i using a id as a primary key it's show only one data then this id i annotat autoGenerate = true then it's show all data which i put in server but when i reopen my app,it's show double data(this mean firstly i have 3 data in server,this app show 3 data but when i reopen or refresh my database it's show 6 data ,every time in refresh it's increasing).but

问题 In my app firstly i am fetching data from server using retrofit then it's saved in room database table then it shows in recyclerview but when i using a id as a primary key it's show only one data then this id i annotat autoGenerate = true then it's show all data which i put in server but when i reopen my app,it's show double data(this mean firstly i have 3 data in server,this app show 3 data but when i reopen or refresh my database it's show 6 data ,every time in refresh it's increasing).but

问题 In my app firstly i am fetching data from server using retrofit then it's saved in room database table then it shows in recyclerview but when i using a id as a primary key it's show only one data then this id i annotat autoGenerate = true then it's show all data which i put in server but when i reopen my app,it's show double data(this mean firstly i have 3 data in server,this app show 3 data but when i reopen or refresh my database it's show 6 data ,every time in refresh it's increasing).but

问题 my task is to migrate the current architecture of our app (using Cupboard) to Room and I am encountering some issues on the very first piece of work, which is migrating the database objects, written in Java for now (Cupboard only supports Java), to make them work with Room. This is an example: public class ItemDb { public Long _id; public String type; public String subtype; public long scheduledTime; public int iteration; public String data1; public String data2; public String data3; and this

问题 I want to achieve the Android Sync Room Database with a Server using PHP and MySQL. Here have a look he has done the same but in SQLite I want this same in-room DB: SQL lite sync 来源： https://stackoverflow.com/questions/65537543/how-to-sync-room-database-with-server

问题 Using SqliteOpenHelper, I can rely on the onCreate() method to initialize some database work if the database is created for the first time. Also, using the onUpdate() method, I can easily detect if the user has an older version of the DB and I can update it easily. Does Room support alternative methods to use? 回答1: 1. SQLiteOpenHelper.onCreate YES, there is Callback class for that. You can add Callback to RoomDatabase.Builder like this Room.databaseBuilder(getApplicationContext(), MyDb.class,

问题 I want to use One to One relationship in room that available from version 2.2.0-alpha1. My current room version 2.2.5 and I get an error: error: Fields annotated with @Relation must be a List or Set. 回答1: There is change in android name since androidx. Make sure to use androidx instead of arch(deprecated) in app def room_version = "2.2.5" implementation "androidx.room:room-runtime:$room_version" annotationProcessor "androidx.room:room-compiler:$room_version" 来源： https://stackoverflow.com