Windows应用商店绑定问题

Question

I have a Windows Store project as follows:

class MyModel
{
    private int _testVar;
    public int TestVariable
    {
        get { return _testVar; }
        set
        {
            _testVar = value;
            NotifyPropertyChanged("TestVariable");
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    private void NotifyPropertyChanged(string property)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(property));
    }


}

My binding is as follows:

<Grid Background="{StaticResource ApplicationPageBackgroundThemeBrush}">
    <TextBlock Text="{Binding Path=TestVariable}" />
    <Button Click="Button_Click_1"></Button>
</Grid>

And the code behind:

    MyModel thisModel = new MyModel();

    public MainPage()
    {
        this.InitializeComponent();

        thisModel.TestVariable = 0;
        DataContext = thisModel;
    }

As this point, the binding appears to work as I get the textblock showing a 0. However, when I handle the button click event as follows:

    private void Button_Click_1(object sender, RoutedEventArgs e)
    {
        thisModel.TestVariable++;
    }

I don't see the number increasing. What am I missing here?

Answer 1

It seems that your class doesn't implement INotifyPropertyChanged . I mean I expected to see class MyModel : INotifyPropertyChanged

Answer 2

First, the view model must implement INotifyPropertyChanged or better use some kind of MVVM Library like MVVM Light , this will help you a lot.
Second, I'm not sure, if the call thisModel.TestVariable++ actually updates the value? Try to use thisModel.TestVariable = thisModel.TestVariable + 1;