notes_bloc.dart

import 'dart:async';

import 'package:stream_post/data/blocs/bloc_provider.dart';
import 'package:stream_post/data/database.dart';
import 'package:stream_post/models/note_model.dart';

class NotesBloc implements BlocBase {
    // Create a broadcast controller that allows this stream to be listened
    // to multiple times. This is the primary, if not only, type of stream you'll be using.
    final _notesController = StreamController<List<Note>>.broadcast();

    // Input stream. We add our notes to the stream using this variable.
    StreamSink<List<Note>> get _inNotes => _notesController.sink;

    // Output stream. This one will be used within our pages to display the notes.
    Stream<List<Note>> get notes => _notesController.stream;

    // Input stream for adding new notes. We'll call this from our pages.
    final _addNoteController = StreamController<Note>.broadcast();
    StreamSink<Note> get inAddNote => _addNoteController.sink;

    NotesBloc() {
        // Retrieve all the notes on initialization
        getNotes();

        // Listens for changes to the addNoteController and calls _handleAddNote on change
        _addNoteController.stream.listen(_handleAddNote);
    }

    // All stream controllers you create should be closed within this function
    @override
    void dispose() {
        _notesController.close();
        _addNoteController.close();
    }

    void getNotes() async {
        // Retrieve all the notes from the database
        List<Note> notes = await DBProvider.db.getNotes();

        // Add all of the notes to the stream so we can grab them later from our pages
        _inNotes.add(notes);
    }

    void _handleAddNote(Note note) async {
        // Create the note in the database
        await DBProvider.db.newNote(note);

        // Retrieve all the notes again after one is added.
        // This allows our pages to update properly and display the
        // newly added note.
        getNotes();
    }
}