Managing State in Flutter Using BLoC Pattern/

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Home Cubit

Home Cubit

Learn how to use Cubits to conditionally show different widgets in your app.

We'll cover the following...

The HomeCubit is the second Cubit that needs to be implemented in our e-commerce app. It helps us accomplish the following tasks:

  • Retrieve the list of categories and products from the products repository.

  • Change pages using the BottomNavigationBar in the home screen, and render the correct AppBar and body of the page.

The available bodies are declared in lib\screens\home_screen\home_screen.dart:

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final List<Widget> widgetOptions = [
  SingleChildScrollView(
    child: ListView(
      shrinkWrap: true,
      physics: const ScrollPhysics(),
      scrollDirection: Axis.vertical,
      children: const [
        CategoriesGrid(),
      ],
    ),
  ),
  const CartScreen(),
];

Implementing HomeState

The state of our app should keep track of the following:

  • The current AppBar that is shown to the user.

  • The current index for the BottomNavigationBar.

  • The current Scaffold body that will be shown to the user.

  • The list of categories that we get from the products repository

Let's define the HomeState abstract class.

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abstract class HomeState {
  PreferredSizeWidget currentAppBar;
  int currentBottomNavigationIndex;
  Widget currentBody;
  List<Category> categories = [];
  HomeState({
    // The current AppBar that is shown to the user
    required this.currentAppBar,
    // The current index for the BottomNavigationIndex
    required this.currentBottomNavigationIndex,
    // The current Scaffold body that will be shown to the user
    required this.currentBody,
    // The list of categories that we get from the products repository
    required this.categories,
  });
}

  • Lines 2–5: Define the properties of the HomeState abstract class, which is used to keep track of the current state of the e-commerce app.

  • Line 2: The currentAppBar property is used to store the PreferredSizeWidget of the current AppBar being displayed to the user.

  • Line 3: The currentBottomNavigationIndex property is used to keep track of the index of the current BottomNavigationBar.

  • Line 4: The currentBody property is used to store the current Scaffold body being displayed to the user.

  • Line 5: The categories property is a list of Category objects obtained from the products repository. ...