Flutter BloC Pattern: CRUD Operations

Table of Contents

1. Introduction
2. What is Flutter?
3. Why Use Flutter Block?
4. Getting Started with Flutter Block
5. Understanding the Concepts of Block, Event, and State
6. Creating the User Model
7. Implementing User List Event
8. Implementing User List State
9. Creating the User List Block
10. Using the User List Block in the App
11. Adding and Deleting Users
12. Updating User Information
13. Conclusion

Introduction

In today's fast-paced world, maintaining and updating the state of an application is crucial. This is where Flutter Block comes in. Flutter Block allows developers to decompose their app state into smaller, well-defined state machines that transform events into 0, 1, or multiple states. If You want to learn Flutter in a better and faster way, join our 12-week Flutter training on HeyFlutter.com. Our structured courses cover various topics, including UI design, state management, Firebase, clean architecture, databases, and more. Whether you're a newbie or an expert, our training will help you master Flutter.

What is Flutter?

Flutter is an open-source UI toolkit created by Google for building natively compiled applications for mobile, web, and desktop from a single codebase. It allows developers to create beautiful and fast apps using a reactive programming paradigm. With Flutter, you can build visually appealing and high-performing user interfaces that seamlessly run on multiple platforms.

Why Use Flutter Block?

When developing Flutter applications, managing the state of the app becomes essential. Flutter Block is a state management library that simplifies this process by breaking down the app state into smaller, manageable pieces called blocks. By using Flutter Block, developers can handle events and transform them into different states Based on their logic. This modular approach to state management improves code organization, testability, and maintainability of the Flutter app.

Getting Started with Flutter Block

To use Flutter Block in your Flutter app, you need to add the flutter_bloc Package to your pubspec.yaml file. This package provides the necessary classes and methods for implementing the Flutter Block pattern in your app. Once you have added the package, you can start using Flutter Block to handle the state of your app efficiently.

Understanding the Concepts of Block, Event, and State

In Flutter Block, there are three main concepts: block, event, and state. A block is a component responsible for managing the state of the app. It listens to events and transforms them into different states based on the implemented logic. An event represents a specific action that occurs in the app, such as adding a user or deleting a user. A state represents the Current state of the app, which can be updated based on the events triggered.

Creating the User Model

Before diving into the implementation of Flutter Block, let's Create a User model. The User model will have properties like name, ID, and email. This model will be used later in the app to add, update, and delete users from the user list.

Implementing User List Event

To handle events related to the user list, we need to create the UserListEvent class. This class acts as an abstract class that defines the different events that can occur in the user list. We will create three events: AddUserEvent, DeleteUserEvent, and UpdateUserEvent. Each event will have associated properties and will extend the UserListEvent class.

Implementing User List State

Next, we need to implement the UserListState class. This class represents the different states that the user list can be in. We will create two states: UserListInitial and UserListUpdated. UserListInitial will be the initial state of the user list, while UserListUpdated will be the state when the user list is updated.

Creating the User List Block

Now, let's create the UserListBlock class. This class will be responsible for managing the state of the user list. It will register event handlers for the AddUserEvent, DeleteUserEvent, and UpdateUserEvent and update the state accordingly. The UserListBlock class will extend the Bloc class provided by the flutter_bloc package.

Using the User List Block in the App

To use the UserListBlock in our app, we need to wrap our MaterialApp widget with the MultiBlocProvider and add the UserListBlock. The MultiBlocProvider is responsible for providing the UserListBlock to all the child widgets that need access to it. This way, we can access the UserListBlock and its state from anywhere in our app.

Adding and Deleting Users

In our app's homepage, we will use the BlockBuilder widget to rebuild the widget tree whenever the state of the UserListBlock changes. In the BlockBuilder widget, we check if the state is an instance of UserListUpdated and the user list is not empty. If so, we assign the user list from the state object and display a ListView.builder widget to Show a list of users. If the state is not an instance of UserListUpdated or the user list is empty, we display a message indicating that no users were found.

Updating User Information

In the UserTile widget, we display each user's information, including their name, email, and buttons to delete or update the user. The onDelete button triggers a DeleteUserEvent, and the onUpdate button triggers an UpdateUserEvent. These events are sent to the UserListBlock, which updates the user list accordingly.

Conclusion

Flutter Block is a powerful state management pattern that allows developers to efficiently handle the state of their Flutter apps. By decomposing the app state into smaller, well-defined state machines, Flutter Block simplifies the process of managing events and transforming them into different states. With Flutter Block, developers can build scalable, maintainable, and testable Flutter apps with ease.

Highlights

• Flutter Block simplifies state management in Flutter apps.
• It decomposes the app state into manageable blocks and handles events and states efficiently.
• Using Flutter Block improves code organization, testability, and maintainability of Flutter apps.
• The UserListBlock class manages the state of the user list and registers event handlers for adding, deleting, and updating users.
• The BlockBuilder widget rebuilds the widget tree whenever the state of the UserListBlock changes.
• The UserTile widget displays each user's information and allows users to be deleted or updated.
• Flutter Block is a versatile and powerful tool for managing the state of Flutter apps.

FAQ

Q: What is Flutter? A: Flutter is an open-source UI toolkit for building natively compiled applications for mobile, web, and desktop.

Q: What is Flutter Block? A: Flutter Block is a state management library that allows developers to decompose the app state into smaller, well-defined state machines.

Q: How does Flutter Block work? A: Flutter Block works by handling events and transforming them into different states based on the implemented logic.

Q: Why should I use Flutter Block? A: Flutter Block simplifies state management, improves code organization, testability, and maintainability in Flutter apps.

Q: How can I use Flutter Block in my app? A: To use Flutter Block, add the flutter_bloc package to your pubspec.yaml file and follow the implementation steps described in the article.

Q: Can Flutter Block handle complex state management scenarios? A: Yes, Flutter Block can handle complex state management scenarios by breaking down the app state into manageable blocks and events.

Q: Is Flutter Block suitable for large-Scale apps? A: Yes, Flutter Block is suitable for large-scale apps as it improves code organization and maintainability.

Q: Can I use Flutter Block with other state management solutions? A: Yes, Flutter Block can be used alongside other state management solutions in your Flutter app.

Q: Does Flutter Block support hot-reloading? A: Yes, Flutter Block supports hot-reloading, allowing developers to quickly see the changes in the app state.

Q: Is Flutter Block suitable for beginners? A: Yes, Flutter Block is suitable for beginners as it provides a structured approach to state management in Flutter apps.