Question

I have been trying to create a fairly simple application in WPF following the MVVM development pattern but I have been going crazy over how difficult it seems to be to do simple things. I have already created this app in Forms and had it successfully running, but my boss requested I rewrite the interface in WPF as a demo of the technology. I decided to try to follow as many best practices as I can in order to make the app and code as educational as possible. My current dilemma is using a listbox to run some code every time the selection changes. I’m ready to just use the code-behind with an event to call the method on the view-model. To me this seems to still be essentially MVVM since no logic is executing. Thanks for any help/insight.

Answer 1

You can do that simply binding selecteditem property of listbox… on selection change a setter in the view model will be called and you can do what ever you want…

Here is a sample which will help you

XAML

  <Grid Canvas.Left="0" Canvas.Bottom="0" Height="300" Width="300" Background="Bisque">
            <ListBox ItemsSource="{Binding Employes}" SelectedItem="{Binding SelectedEmploye}"/>
        </Grid>

View Model

public  class ViewModel : ViewModelBase
    {
        private List<Employee> _employes;

        public List<Employee> Employes
        {
            get { return _employes; }
            set { _employees = value; OnPropertyChanged("Employes"); }
        }
        private Employee _selectedEmploye;

        public Employee SelectedEmploye
        {
            get { return _selectedEmploye; }
            set
            {
                _selectedEmployee = value;
                OnPropertyChanged("SelectedEmploye");
            }
        }

    }

View model base

public  class ViewModelBase : INotifyPropertyChanged
    {
        protected virtual void OnPropertyChanged(string propertyName)
        {
            if (this.PropertyChanged != null)
            {
                this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
        public event PropertyChangedEventHandler PropertyChanged;
    }

Employee Class

public class Employee : ViewModelBase
    {
        private string _name;
        public string Name
        {
            get { return _name; }
            set { _name = value; }
        }
    }