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Yanshof
Yanshof

Reputation: 9926

Why my binding does not work?

Have class behine the xaml that contain the propertie 'Int32 Count'

I want to bind some TextBlock to the 'Count' value - that the TextBlock.Text will have the value of the 'Count'.

So i wrote in the xaml :

 <TextBlock Text="{ Binding Path=Count }" />

And in the code behind the xaml i add to the constructor:

  DataContext = this;

But each change of the 'Count' does not change the text of the TextBlock.

The code of 'Count' 

Int32 count;
public Int32 Count
{
      get
      {
           return count;
      }

      set
      {
           count = value;
      }

}

Upvotes: 0

Views: 169

Answers (2)

Vinny Marquez
Vinny Marquez

Reputation: 547

place the INotifyPropertyChanged interface to your class: 

public class MainPage : INotifyPropertyChanged
{

}

then implement:

public event PropertyChangedEventHandler PropertyChanged;

protected void OnPropertyChanged(string propertyname)
        {
            var handler = PropertyChanged;
            if (handler != null)
                handler(this, new PropertyChangedEventArgs(propertyname));
        }

what this does if provide the mechanism for notifying the view that something has changed in your datacontext and you do it like this:

public Int32 Count
{
      get
      {
           return count;
      }

      set
      {
           count = value;
           OnPropertyChanged("Count"); //This invokes the change
      }

}

But of course, i recommend that you separate design and code using the MVVM pattern. This way, you can implement the propertychanged to a ViewModelBase class, then inherit that for each of your ViewModels.

Upvotes: 4

Felice Pollano
Felice Pollano

Reputation: 33252

You should ensure your DataContext implements INotifyPropertyChanged. Then you have to fire the property change events properly.

Upvotes: 0

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