Clear entry text from ViewModel using RelayCommand

Question

I would like to clear entry text from my ViewModel which is binded there. In the code below I tried it by using a RelayCommand, but it doesn't work.

What i want to accomplish: When clicking button named AddQuestionToQuiz, a function is executed by using Command on the button. The function OnCreateQuizClick(), located in my ViewModel, is triggerd and this function needs to clear my entry text, which i don't get for the moment.

I also tried to use a regular Command instead of using a RelayCommand, but also here it doesn't want to work.

EDIT: UNDERNEATH CODE WORKS FINE - GOT UPDATED Code is used to clear entry text when clicking on a button from your ViewModel, implementing INotifyPropertyChanged Interface

.xaml - code

<Button x:Name="AddQuestionToQuiz" WidthRequest="200" Command="{Binding CreateQuizCommand}" Style="{StaticResource ButtonStyle}" Text="Add question to quiz"></Button>

ViewModel - code

internal class CreateQuizPageViewModel : INotifyPropertyChanged
{
    // Quiz Name Input
    public String QuizNameInput { get; set; }

    private String quizQuestionInput = "";
    public String QuizQuestionInput 
    {
        get { return quizQuestionInput; }   
        set { quizQuestionInput = value; OnPropertyChanged(); }
    } 

    public RelayCommand CreateQuizCommand { get; set; }

    public CreateQuizPageViewModel()
    {
        CreateQuizCommand = new RelayCommand(OnCreateQuizClick);
    }

    public event PropertyChangedEventHandler PropertyChanged;

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

    public void OnCreateQuizClick()
    {
        QuizQuestionInput = "";
    }
}

your VM does not implement `INotifityPropertyChaged` so the UI is not being notified of changes to the VM — Jason, Nov 23 '21 at 12:38
I edited my code above by a working example (ViewModel is updated), Thanks @Jason. Also works by using a normal Command instead of a Relay Command — AntoBoy, Nov 23 '21 at 12:49
Instead of adding the working code to the question, please add it as "Your Answer" below. This makes it easier for anyone who sees this question to realize that it has been answered. Thanks. — ToolmakerSteve, Nov 23 '21 at 15:31

score 0 · Accepted Answer · answered Nov 24 '21 at 08:58

EDIT: VIEWMODEL UPDATED

.xaml - code

<Button x:Name="AddQuestionToQuiz" WidthRequest="200" Command="{Binding CreateQuizCommand}" Style="{StaticResource ButtonStyle}" Text="Add question to quiz"></Button>

ViewModel - code

internal class CreateQuizPageViewModel : INotifyPropertyChanged
{
    // Quiz Name Input
    public String QuizNameInput { get; set; }

    private String quizQuestionInput = "";
    public String QuizQuestionInput 
    {
        get { return quizQuestionInput; }   
        set { quizQuestionInput = value; OnPropertyChanged(); }
    } 

    public RelayCommand CreateQuizCommand { get; set; }

    public CreateQuizPageViewModel()
    {
        CreateQuizCommand = new RelayCommand(OnCreateQuizClick);
    }

    public event PropertyChangedEventHandler PropertyChanged;

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

    public void OnCreateQuizClick()
    {
        QuizQuestionInput = "";
    }
}

Clear entry text from ViewModel using RelayCommand

1 Answers1