What are the most effective design patterns for MVVM refactoring?

1 The MVVM pattern

The MVVM pattern is a popular architectural pattern for building user interfaces, especially for platforms like WPF, Xamarin, and Angular. It consists of three main components: the Model, the View, and the ViewModel. The Model represents the data and business logic of your application. The View is the user interface that displays the data and reacts to user actions. The ViewModel is the bridge between the Model and the View, exposing the data and commands to the View and handling the interaction logic. The MVVM pattern enables a clear separation of concerns, decoupling the View from the Model and allowing for easier testing and reuse of code.

2 The Facade pattern

The Facade pattern is a structural design pattern that provides a simplified and unified interface to a complex system or subsystem. It can be useful for refactoring your MVVM code when you have a large and complicated Model that contains many classes and dependencies. By creating a Facade class that encapsulates the Model and exposes only the relevant methods and properties to the ViewModel, you can reduce the coupling and complexity of your code and make it easier to understand and modify. For example, if your Model consists of several services that communicate with a database, a web API, and a third-party library, you can create a Facade class that wraps these services and provides a single point of access for the ViewModel.

3 The Mediator pattern

The Mediator pattern is a behavioral design pattern that defines an object that coordinates the communication between a set of objects. It can be useful for refactoring your MVVM code when you have multiple ViewModels that need to exchange information or trigger actions in each other. By creating a Mediator class that acts as a hub for the ViewModels, you can avoid direct dependencies and references between them and make your code more loosely coupled and flexible. For example, if you have a main ViewModel that contains several child ViewModels that represent different parts of your user interface, you can use a Mediator class to broadcast messages and events between them.

4 The Strategy pattern

The Strategy pattern is a behavioral design pattern that defines a family of interchangeable algorithms that can be selected at runtime. It can be useful for refactoring your MVVM code when you have a ViewModel that needs to perform different actions or calculations depending on the context or user input. By creating a Strategy interface that defines a common method and implementing different concrete classes that represent different algorithms, you can delegate the execution logic to the Strategy objects and make your ViewModel more adaptable and extensible. For example, if you have a ViewModel that needs to apply different filters or sorting criteria to a data collection, you can use a Strategy interface to define a Filter or Sort method and create different classes that implement different filtering or sorting algorithms.

5 The Observer pattern

The Observer pattern is a behavioral design pattern that defines a one-to-many relationship between a subject and multiple observers, where the subject notifies the observers of any state changes. It can be useful for refactoring your MVVM code when you have a ViewModel that needs to update the View or other components when its data or state changes. By implementing the Observer pattern, you can ensure that the View or other components are always in sync with the ViewModel and react accordingly. For example, if you have a ViewModel that contains a property that represents the progress of a long-running task, you can use the Observer pattern to notify the View or other components of the progress changes and update the user interface accordingly.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?