Refresh fragment on back to previous fragment

user_5464294 0
Viewed 847

That is what I have in my app

  • Activity with 2 fragment with ViewModels and Databinding.
  • Room Database with Livedata to update UI continuously.
  • Navigation Controller to navigate between fragments.
  • Fragment #1 have RecyclerView (List of Custom Object).
  • Fragment #2 is to Insert or Update operations (Transactions).

Everything works fine as expected, but one thing I can't figure out why it happens.

When I go to Fragment #2 to Insert or Update data to Room Database then back to Fragment #1 with (top or bottom) back button, fragment #1 doesn't reload and data doesn't change (update) until I reload data.

In other case when I Insert or Update data at the same fragment the list changes immediately.

Do I have to make insert and update operations at the same fragment?

Can't I do it at other fragments and when I go back to the list fragment I find that data is been updated?

Keep in mind that it was work like I hope but at some point i really don't know it doesn't any more !!

android-livedata android-room android-fragments uinavigationcontroller android
2 Answers

After searching, the problem was that I was create instance from repository which contain ROOM database DAO, So all LIVEDATA connections to the database was removed

The solution was to use singleton pattern, which mean to use only one repository instance and one room database instance during the full lifecycle of the activity which contain my fragments.

You can do this many ways, I recommend you to use Dependences Injection Tool I used was HILT DAGGER here here

user_54642940

Create a function in class where fragments are defined like this.

 public void refresh( ) {
        fragment = new  ListFragment();
        fm = getSupportFragmentManager();
        ft = fm.beginTransaction();
        if (fragment != null) {
            FragmentManager fm = getSupportFragmentManager();
            fm.beginTransaction().replace(R.id.container, fragment).commit();
        }
    }

Now Call that in your 2nd fragment where you want to call 1st fragment after any action.

((MainActivity) Objects.requireNonNull(getActivity())).refresh();
user_125967130
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