使用带有搜索视图的 LiveData 项目过滤 RecyclerView 的列表 [英] Filter RecyclerView's list with LiveData items with searchview

问题描述

我决定优化我的代码，因此切换到 liveData.我遵循了 youtube 上的教程(youtube 链接)但我不太明白如何在用户输入单词时过滤我的 recyclerView，因为我没有在我的适配器中存储任何列表.我在 MainActivity 上使用了一个简单的搜索视图过滤系统.

I decided to optimize my code and therefore switch to liveData. I followed a tutorial on youtube (youtube link) but I do not quite understand how I can filter my recyclerView when the user enters a word since I do not store any list in my Adapter. I use a simple searchview filter system on my MainActivity.

此外，我使用 DiffUtil 更新我的 recyclerView 并更新我的适配器，感谢:

Moreover, I use DiffUtil to update my recyclerView and I update my Adapter thanks to:

noteViewModel = new ViewModelProvider.AndroidViewModelFactory(getApplication()).create(NoteViewModel.class);
noteViewModel.getAllNotes().observe(this, adapter::submitList);

我的代码与视频几乎相同，但这是其中的一部分:

My code is almost identical to the video but here is a part of it:

视图模型:

public class NoteViewModel extends AndroidViewModel {
    private NoteRepository repository;
    private LiveData<List<Note>> allNotes;

    public NoteViewModel(@NonNull Application application) {
        super(application);
        repository = new NoteRepository(application);
        allNotes = repository.getAllNotes();
    }

    public void insert(Note note) {
        repository.insert(note);
    }

    public void update(Note note) {
        repository.update(note);
    }

    public void delete(List<Note> notes) {
        repository.delete(notes);
    }


    public LiveData<List<Note>> getAllNotes() {
        return allNotes;
    }
}

我的仓库:

public class NoteRepository {

    private NotesDAO notesDAO;
    private LiveData<List<Note>> allNotes;

    public NoteRepository(Application application) {
        NotesDB database = NotesDB.getInstance(application);
        notesDAO = database.notesDAO();
        allNotes = notesDAO.getAllNotes();
    }

    public void insert(Note note) {
        new InsertNoteAsyncTask(notesDAO).execute(note);
    }

    public void update(Note note) {
        new UpdateNoteAsyncTask(notesDAO).execute(note);
    }

    public void delete(List<Note> note) {
        new DeleteNoteAsyncTask(notesDAO).execute(note);
    }


    public LiveData<List<Note>> getAllNotes() {
        return allNotes;
    }

    private static class InsertNoteAsyncTask extends AsyncTask<Note, Void, Void> { // SOME STUFF }

    private static class UpdateNoteAsyncTask extends AsyncTask<Note, Void, Void> { // SOME STUFF }

    private static class DeleteNoteAsyncTask extends AsyncTask<List<Note>, Void, Void> { // SOME STUFF }

}

推荐答案

最后，感谢@EpicPandaForce，我做到了:

Finally, thanks to @EpicPandaForce, I did that:

我的视图模型:

public class NoteViewModel extends AndroidViewModel {

    private NoteRepository repository;
    private final LiveData<List<Note>> allNotes;
    private MutableLiveData<String> filterText = new MutableLiveData<>();

    public NoteViewModel(@NonNull Application application) {
        super(application);
        repository = new NoteRepository(application);
        allNotes = Transformations.switchMap(filterText, (input) ->
        {
            if(input == null || input.equals(""))
                return repository.getAllNotes();
            else
                return repository.filter(input);
        });
        }

        public void setFilter(String query) {
            filterText.setValue(query);
        }

        public LiveData<List<Note>> getAllNotes() {
            return allNotes;
        }
}

在我的存储库中:

public LiveData<List<Note>> filter(String input) {
        try {
            return new FilterNoteAsyncTask(notesDAO).execute(input).get();
        } catch (ExecutionException | InterruptedException e) {
            e.printStackTrace();
        }
        return null;
    }

private static class FilterNoteAsyncTask extends AsyncTask<String, Void, LiveData<List<Note>>> {
        private NotesDAO notesDAO;

        private FilterNoteAsyncTask(NotesDAO notesDAO) {
            this.notesDAO = notesDAO;
        }

        @Override
        protected LiveData<List<Note>> doInBackground(String... strings) {
            return notesDAO.filter(strings[0]);
        }
    }

我在数据库中执行请求感谢:

And I perform the request in the database thanks to:

@Query("SELECT * FROM note_table WHERE LOWER(title) LIKE '%' || :search || '%'")
LiveData<List<Note>> filter(String search);

这篇关于使用带有搜索视图的 LiveData 项目过滤 RecyclerView 的列表的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！