MVVM Architecture

The MVVM (Model-View-ViewModel) architecture pattern is widely used in software development, particularly in applications that utilize data binding. It helps separate the development of the graphical user interface from the business logic or back-end logic.

2.1 Definitions

• Model: Represents the data and business logic of the application. It notifies the ViewModel about changes to data.
• View: The user interface of the application, displaying the data and sending user commands to the ViewModel.
• ViewModel: Acts as an intermediary between the View and the Model. It retrieves data from the Model and makes it available to the View.

3.1 Data Binding

Data binding is a key feature of MVVM. It allows automatic synchronization of data between the View and ViewModel.

3.2 Commands

Commands are used in MVVM to handle user interactions. They are associated with the ViewModel to execute business logic in response to user actions.

4.1 Example Code

Here is a simple example of how the MVVM pattern can be implemented in a WPF application:

public class Person
{
    public string Name { get; set; }
}

public class PersonViewModel : INotifyPropertyChanged
{
    private Person person;
    
    public PersonViewModel()
    {
        person = new Person { Name = "John Doe" };
    }
    
    public string Name
    {
        get { return person.Name; }
        set
        {
            person.Name = value;
            OnPropertyChanged("Name");
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    protected void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}
                    

• Keep the ViewModel free of any UI logic.
• Use ICommand for handling user input instead of event handlers.
• Ensure the Model is independent of the View and ViewModel.
• Leverage Dependency Injection for better testability.