CODEWITHSUNDEEP
wpfbindinginotifypropertychanged
user979033
user979033

Reputation: 6450

PropertyChangedEventHandler for static variable not changing

I wonder how to update my UI with my static property. I have 2 properties in my model and one of them is static:

public class Machine : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;
    public static event PropertyChangedEventHandler StaticPropertyChanged;
    public string _name;
    public static int _counter;

    public void AddMachine(Machine machine)
    {
        _counter++;
    }

    public string Name
    {
        get { return _name; }
        set
        {
            _name = value;
            NotifyPropertyChange("Name");
        }
    }

    public static int Counter
    {
        get { return _counter; }
        set
        {
            _counter = value;
            OnStaticlPropertyChanged("Counter");
        }
    }

    public virtual void NotifyPropertyChange(string propertyName)
    {
        var handler = PropertyChanged;
        if (handler != null)
            handler(this, new PropertyChangedEventArgs(propertyName));
    }

    public static void OnStaticlPropertyChanged(string propertyName)
    {
        var handler = StaticPropertyChanged;
        if (handler != null)
            StaticPropertyChanged(
                typeof(Machine),
                new PropertyChangedEventArgs(propertyName));
    }
}

As you can see i created another PropertyChangedEventHandler for my static value. The other property (not the static one - Name) is working fine. I am holding my object in collection:

public ObservableCollection<Machine> machines { get; set; }

And i can see the Counter is changing but not updating my UI, this is how i am trying to update my UI using TextBlock:

<TextBlock Name="tbStatusBar" Text="{Binding Source={x:Static my:Machine.Counter}}" />

So my question is what am I doing wrong ?

Upvotes: 0

Views: 232

Answers (1)

Clemens
Clemens

Reputation: 128061

First, you have to make sure to use WPF 4.5, as the StaticPropertyChanged event mechanism won't work with an older version.

Then, in AddMachine, you should update the property, not its backing field:

public void AddMachine(Machine machine)
{
    Counter++;
}

Finally, you have to change the binding expression from a static source to a path to a static property (note the parenthesis):

<TextBlock Text="{Binding Path=(my:Machine.Counter)}" />

Upvotes: 1

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