Update some specific field of an entity in android Room

Question

I am using android room persistence library for my new project  I want to update some field of table   I have tried like in my Dao -     Method 1    Dao public interface TourDao        Update     int updateTour Tour tour       But when I try to update using this method then it updates every field of the entity where it matches primary key value of tour object  I have used  Query     Method 2    Query  UPDATE Tour SET endAddress    end address WHERE id    tid   int updateTour long tid  String end address     It is working but there will be many queries in my case because I have many fields in my entity  I want to know how can I update some field  not all  like Method 1 where id   1   id is the auto generate primary key       Entity    Entity public class Tour        PrimaryKey autoGenerate   true      public long id      private String startAddress      private String endAddress        constructor  getter and setter

User · Answer

You could try this  but performance may be worse a little    Dao public abstract class TourDao         Query  SELECT   FROM Tour WHERE id     id       public abstract Tour getTour int id         Update     public abstract int updateTour Tour tour        public void updateTour int id  String end address            Tour tour   getTour id           tour end address   end address          updateTour tour

User · Answer

According to SQLite Update Docs      lt  -- language  lang-java -- gt   Query  UPDATE tableName SET      field1    value1      field2    value2                 some more fields to update             field N   value N     WHERE id    id   int updateTour long id                  Type value1                  Type value2                                          some more values here                                     Type value N     Example    Entity    Entity tableName    orders   public class Order     NonNull  PrimaryKey  ColumnInfo name    order id   private int id    ColumnInfo name    order title   private String title    ColumnInfo name    order amount   private Float amount    ColumnInfo name    order price   private Float price    ColumnInfo name    order desc   private String description          methods  getters  setters     Dao     Dao public interface OrderDao     Query  SELECT   FROM orders   List lt Order gt  getOrderList      Query  SELECT   FROM orders   LiveData lt List lt Order gt  gt  getOrderLiveList      Query  SELECT   FROM orders WHERE order id   orderId   LiveData lt Order gt  getLiveOrderById int orderId          Updating only price   By order id     Query  UPDATE orders SET order price  price WHERE order id    id   void update Float price  int id          Updating only amount and price   By order id     Query  UPDATE orders SET order amount    amount  price    price WHERE order id   id   void update Float amount  Float price  int id          Updating only title and description   By order id     Query  UPDATE orders SET order desc    description  order title   title WHERE order id   id   void update String description  String title  int id     Update void update Order order     Delete void delete Order order     Insert onConflict   REPLACE  void insert Order order

User · Answer

I think you don t need to update only some specific field  Just update whole data       Update query   It is a given query basically  No need to make some new query    Dao interface MemoDao         Insert     suspend fun insert memo  Memo        Delete     suspend fun delete memo  Memo        Update     suspend fun update memo  Memo      Memo class   Entity data class Memo        PrimaryKey autoGenerate   true  val id  Int       ColumnInfo name    title   val title  String        ColumnInfo name    content   val content  String        ColumnInfo name    photo   val photo  List lt ByteArray gt       Only thing you need to know is  id   For instance  if you want to update only  title   you can reuse  content  and  photo  from already inserted data  In real code  use like this  val memo   Memo id  title  content  byteArrayList  memoViewModel update memo

User · Answer

I want to know how can I update some field not all  like method 1 where id   1  Use  Query  as you did in Method 2   is too long query in my case because I have many field in my entity  Then have smaller entities  Or  do not update fields individually  but instead have more coarse-grained interactions with the database  IOW  there is nothing in Room itself that will do what you seek  UPDATE 2020-09-15  Room now has partial entity support  which can help with this scenario  See this answer for more

User · Answer

As of Room 2 2 0 released October 2019  you can specify a Target Entity for updates  Then if the update parameter is different  Room will only update the partial entity columns  An example for the OP question will show this a bit more clearly    Update entity   Tour  class  fun update obj  TourUpdate    Entity public class TourUpdate        ColumnInfo name    id       public long id       ColumnInfo name    endAddress       private String endAddress      Notice you have to a create a new partial entity called TourUpdate  along with your real Tour entity in the question  Now when you call update with a TourUpdate object  it will update endAddress and leave the startAddress value the same  This works perfect for me for my usecase of an insertOrUpdate method in my DAO that updates the DB with new remote values from the API but leaves the local app data in the table alone

User · Answer

If you need to update user information for a specific user ID  x      you need to create a dbManager class that will initialise the database in its constructor and acts as a mediator between your viewModel and DAO  and also    The ViewModel will initialize an instance of dbManager to access the database   The code should look like this       Entity     class User       PrimaryKey     String userId      String username             Interface UserDao        forUpdate      Update     void updateUser User user             Class DbManager        AppDatabase gets the static object o roomDatabase      AppDatabase appDatabase      UserDao userDao      public DbManager Application application        appDatabase   AppDatabase getInstance application          getUserDao is and abstract method of type UserDao declared in AppDatabase   class     userDao   appDatabase getUserDao                public void updateUser User user  boolean isUpdate       new InsertUpdateUserAsyncTask userDao isUpdate  execute user                public static class InsertUpdateUserAsyncTask extends AsyncTask lt User  Void  Void gt           private UserDao userDAO       private boolean isInsert        public InsertUpdateBrandAsyncTask BrandDAO userDAO  boolean isInsert           this  userDAO   userDAO         this isInsert   isInsert                Override      protected Void doInBackground User    users           if  isInsert      userDAO insertBrand brandEntities 0           else       for update     userDAO updateBrand users 0          try           Thread sleep 1000           catch  InterruptedException e            e printStackTrace                   return null                             Class UserViewModel       DbManager dbManager       public UserViewModel Application application        dbmanager   new DbMnager application                public void updateUser User user  boolean isUpdate        dbmanager updateUser user isUpdate                      Now in your activity or fragment initialise your UserViewModel like this   UserViewModel userViewModel   ViewModelProviders of this  get UserViewModel class     Then just update your user item this way  suppose your userId is 1122 and userName is  xyz  which has to be changed to  zyx    Get an userItem of id 1122 User object    User user   new user     if user getUserId      1122      user setuserName  zyx       userViewModel updateUser user         This is a raw code  hope it helps you   Happy coding

User · Answer

after trying to fix a similar problem my self  where I had changed from  PrimaryKey autoGenerate   true  to int UUID  I couldn t find how to write my migration so I changed the table name  it s an easy fix  and ok if you working with a personal small app

User · Answer

We need the primary key of that particular model that you want to update  For example   private fun update Name  String   Brand  String         val deviceEntity   remoteDao  getRemoteId Id      if  deviceEntity    null          remoteDao  insertDevice DeviceEntity DeviceModel   DeviceName  DeviceBrand   DeviceBrand       else         DeviceDao  updateDevice DeviceEntity deviceEntity id remoteDeviceModel   DeviceName  DeviceBrand   DeviceBrand      In this function  I am checking whether a particular entry exists in the database if exists pull the primary key which is id over here and perform update function  This is the for fetching and update records   Query  quot SELECT   FROM   DeviceDatabase DEVICE TABLE NAME  WHERE   DeviceDatabase COLUMN DEVICE ID     DeviceId LIMIT 1 quot    fun getRemoteDeviceId DeviceId  String    DeviceEntity    Update onConflict   OnConflictStrategy REPLACE  fun updatDevice item  DeviceEntity   Int

[android] Update some specific field of an entity in android Room

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