[Part 2] How to Update and Delete data from local database using Room Database in Android Studio
RoomDatabase ensures direct access to the underlying database implementation. It ties together Entities and Daos to create one cohesive database. The RoomWordsSample app that we created deletes and re-creates the data whenever the user opens the app. This behavior isn't ideal, because users will want their added words to remain in the database when the app is closed. Hence updating the app is necessary so that when it opens, the initial data set is only added if the database has no data.
Follow the steps to know How to Update and Delete data from the local database using Room Database in android studio:-
1. Create your new android studio project and add room database and recycle view library.
2. Initialize your data after detecting whether the database contains data already. Run a query to get one data item. If the query returns nothing, then the database is empty.
3. Now Add a method to the DAO to get a single word. The room will issue the database query when the getAnyWord() method is called and returns an array containing one word.
4. In PopulateDBAsync, update the doInBackground() method to check whether the database has any words before initialising the data.
5. Run your app and add several new words.
6. Close the app and restart it. Now words will persist when the app is closed and opened again.
7. Add the deleteAll() method to the DAO and annotate it with the relevant database operation.
8. Now, Add the method to the WordRepository class and Write the code to run the method in the background.
9. Call the method in the WordRepository class, add the method to the WordViewModel.
10. To Add the Clear all data menu option, In menu_main.xml, change the menu option title and id by implementing the onOptionsItemSelected() method to invoke the deleteAll() method on the WordViewModel object in MainActivity.
11. Now Run your app and In the Options menu, select Clear all data. Restart the app to see the initial set of words.
12. To Delete a single word, Add deleteWord() method to the DAO, WordRepository class And WordViewModel class and annotate it.
Chapters:
00:00 Intro
00:44 Ui implementation
02:30 Create Query
05:00 code implementation
13:00 Project Run Successfully
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