6.8. Widgets in Flutter: Data Persistence

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Flutter is a user interface (UI) development kit created by Google to build beautiful, natively compiled apps for mobile, web, and desktop from a single codebase. At the heart of Flutter are Widgets, which are the basic building blocks of the UI in Flutter. In this article, we're going to focus on one particular aspect of Flutter widgets: data persistence.

In Flutter programming, widgets are immutable. This means that, once created, a widget cannot be changed. Instead, when the data changes, the widget is rebuilt. This might seem inefficient at first glance, but Flutter is optimized for fast widget rebuilding, making this approach viable. However, this raises the question of how to persist the data across widget rebuilds. This is where data persistence comes in.

Data persistence refers to the practice of saving data to a persistent storage location, such as a database or file, so that the data can be retrieved even after the application is closed and restarted. In Flutter, there are several ways to achieve data persistence.

A common way to persist data in Flutter is using the shared_preferences package. This package provides a way to store simple data like integers, strings, booleans and lists of simple data persistently. To use shared_preferences you first need to add the dependency to your pubspec.yaml file and then you can use SharedPreferences.getInstance() to get an instance of SharedPreferences and use methods like setString, setInt, setBool etc. store data. To retrieve data, you can use methods like getString, getInt, getBool, etc.

Another way to persist data in Flutter is using an SQLite database. SQLite is an embedded relational database that is very useful for storing more complex data. To use SQLite in Flutter, you can use the sqflite package. Similar to shared_preferences, you need to add the dependency to your pubspec.yaml file. After that, you can use openDatabase to open a database and then use methods like rawQuery, rawInsert, rawUpdate, rawDelete, etc. to interact with the database.

In addition to these, there are many other packages and tools you can use to persist data in Flutter, such as Hive, Moor, Firebase, etc. The choice of data persistence method depends on the specific needs of your application.

It is important to note that data persistence is only one part of state management in Flutter. State management is a complex topic that involves not only persisting data, but also communicating between widgets, reacting to data changes, and so on. There are many different approaches to state management in Flutter such as Provider, Riverpod, Bloc, Redux, etc. The choice of state management approach depends on the specific needs of your application and your personal preferences.

In short, data persistence is an important part of Flutter app development. Whether using shared_preferences for simple data, SQLite for more complex data, or any of the many other methods available, data persistence allows you to create applications that can retain their data across application restarts, making your applications more usable and user-friendly. the user.

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816.9. Widgets in Flutter: Animations in Flutter