![]() That’s why I don’t like state management libraries. In my opinion, it’s a problem if one of the dependencies starts dictating how you develop your app. When it comes to making decisions about dependencies for a project, I’m trying to add as few libraries as possible and as least intrusive as possible. ![]() We will focus on implementation but here you can find the overall picture. I won’t go into MVVM theory and diagrams, I’m sure you can find very good materials explaining the concept. For smaller apps MVVM may be unnecessarily complex. Of course, you need to calibrate the type of architecture, depending on what kind of app you’re going to build. One of them is MVVM, which is my personal favorite for commercial projects. There are quite a few architecture patterns out there. An additional benefit is that you will have common ground with other developers on what should be where just by looking at the code base structure. That’s why you need to make correct choices about the structure of your code and how to separate responsibilities in a manageable, testable and scalable way, meaning choosing architecture. import 'package:provider/provider.If you’ve been into software development for some time, you’ve probably realized that at some point an app becomes so big that it's difficult to navigate through the code and make changes. So for each screen, you have a ChangeNotifierProvider just above the screen widget. In a simple screen-based app, each view has a single view model. This should be just above the higher widget that needs to consume the view model. This wighet comes from the provider package we installed in the setup phase. ChangeNotifierProvider is the widget that initially creates the view model and provides it to whatever descendant requires to consume it. Now that we have a "view model" we need to bind it with the "view". ![]() import 'package:flutter/foundation.dart' Ĭlass MyHomePageViewModel extends ChangeNotifier my_home_page_view_model.dart View ChangeNotifierProvider This "notification" happens with the notifyListeners() call. This allows the view model to notify the view when things have changed and a redraw is needed. It's a kind of an Observable interface if you are familiar with the term. Whatever is not related to how things will be drawn on the screen, should live here. This is where your "business logic" will live. ![]() Head to your pubspec.yaml and add a dependency to the provider package (check pub.dev for the latest version). Provider offers a way for (stateful) widgets to get notified when a change happens in the view model that requires a call to build() to redraw the UI. But this is not very convenient for a sizable app, especially when changes happen deep down in the widget hierarchy. To make Flutter redraw the screen you need to call setState(). It's a bit more concise than a tutorial and a bit more verbose than a cheat sheet. This post aims to give you an intro into the state management method as quickly as possible. There are plenty of great resources about the Provider state management. I will focus on the most simple yet scalable way (that is officially recommended): the provider way. The Flutter community came up with various ways to do state management. Where is your business logic going to live? Next to the UI building logic?įlutter is quite opinionated on how to draw things on the screen but leaves how to organize state management and business logic to you. You've only read about widgets and how to draw things on the screen. It's indeed a pleasure to develop and you can see your changes without a reload! You think you must create an app to give it a go.īut wait. You get excited that you can express yourself and create so much so quickly if what it promises is true.
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