MVVM (Model-View-ViewModel) is a software design pattern commonly used, especially in developing user interfaces. Derived from the Model-View-Controller (MVC) pattern, MVVM is widely preferred in modern application development approaches. Its core components include:
Model:
- Represents the data layer of the application, often communicating with databases or external sources (APIs, file systems, etc.) and performing logical operations for data processing, storage, and retrieval.
- Typically represented as simple data objects (POJOs – Plain Old Java Objects, DTOs – Data Transfer Objects, etc.).
View:
- Represents the user interface, used to display data to users and capture user interactions (clicks, touches, keyboard inputs, etc.).
- Defined typically through files such as XML files (for Android) or HTML, CSS, and JavaScript code (for web).
ViewModel:
- Acts as a link between View and Model. It provides the data to be displayed by the View and handles user interactions.
- Retrieves, processes, and presents necessary data using the Model.
- Often manages aspects such as user interface logic, state, and behavior.
- Not dependent on the View, thus increasing reusability and enabling testability.
The MVVM pattern organizes the relationships between Model, View, and ViewModel, reducing dependencies and making the code more modular, maintainable, and reusable. It also facilitates writing testable code and enhances development efficiency, particularly in modern application development platforms like Android, iOS, and the web, where MVVM is frequently favored.