The Model-View-ViewModel (MVVM) pattern in Angular

The Model-View-ViewModel (MVVM) pattern is a way to create software that uses a ViewModel to separate the user interface (View) from the business logic (Model). Angular is mostly focused on components, but you may see and use some parts of MVVM in Angular apps, especially because it has excellent support for data binding.

 

Here's how the ideas of MVVM fit with Angular:

•  Model  This is your data and business logic. In Angular, your Models are usually just basic TypeScript classes or interfaces that show how your data is structured. The Model represents the application's data and business logic. In Angular, this is typically handled by services or classes that manage data operations.
• View: This is the part of the program that the user sees and interacts with. In Angular, the View is represented by your component's HTML template.
• ViewModel: This connects the Model and the View. It exposes the data from the Model in a way that is easily consumable by the View and takes care of logic that is specific to the View. The ViewModel acts as a mediator between the View and the Model. In Angular, this is typically the component class that holds the logic for data binding and user interaction.

 

 

Mapping between Model and ViewModel in Angular:

• Data Binding: Angular's two-way data binding (like [(ngModel)]) makes it possible for the View and ViewModel to stay in sync automatically. One-way data binding ({{}} for interpolation, [] for property binding, and () for event binding) is also very important for data flow.
• Observables: Angular's usage of RxJS Observables (for things like HTTP requests and changes to form control values) works well with the reactive aspect that is commonly associated with ViewModels. You can make Observables available from your component (ViewModel) so that the template can use the async pipe to subscribe to them.
•  Services are the Model layer that the component (ViewModel) interacts with. They are intended to group together reusable business logic and data access.

 

 

Advantages of MVVM in Angular

• Separation of Concerns: This separates the UI logic from the business logic, which makes the software more modular and easier to maintain.
• Testability: It's easier to develop unit tests for services and components separately.
• Reusability: You can use components and services in other portions of the application.
•  aintainability: Changes are easier to make and update because they are limited to certain layers.