There are many ways to architect an app in Flutter, and just about as many frameworks out there to do it for you! With this in mind, we thought it might be nice to talk about how we build scaleable apps without a large framework, using only Provider, and some simple application tiers.

NOTE: The first portion of this post is a pre-amble about the architecture we are using, and some rationale behind why we think it’s effective. You can skip this if you want and just  get to the code, or follow along with the example over on github:  https://github.com/gskinnerTeam/flutter-mvcs-hello-world

MVC+S Architecture

In classic MVC,  by definition, the Model: “directly manages the data, logic, and rules of the application“, and it is common in MVC discussions to read statements like “business logic goes in the model“. In practice, this works for small components and views, but we find it breaks down quickly when applied to a full application.

This is because it overloads the models with too much responsibility. Unchecked, this can push you to scatter application-level logic across various views in your application, create confusion about where the code should go for any given behavior and lead to large Models that are hard to work with.

The main issue with the classic definitions of MVC, in an application context, is that the terms “business logic “or “rules of the application” are too ambiguous to be useful. Instead, applications tend to break down into Domain Logic (rules around data storage, manipulation, and validation) and Application Logic (what your application actually does. How it behaves.) You also find that:

• Domain Logic naturally belongs in the Model tier.
• Application Logic naturally belongs in the Controller tier.

This requires a robust “Controller” layer in your architecture that is separate from both the View and the Model. Something beyond basic view controllers, that is more “god-like”. A tier that can encapsulate any re-usable behavior or logical sequence of events in your app and be easily re-used across multiple Views.

#code #flutter #open source #source code #mvc