CODEWITHSUNDEEP
c#wpf
Mark
Mark

Reputation: 209

OnPropertyChange does not exist in the current context?

Cant seem to see where I am going wrong? the OnPropertyChange is not being recondnised any suggestions?

  public class MedicationList : INotifyPropertyChanged 
{



    public int MedicationID { get; set; }

    public string Description
    {
        get
        {
            return Description;
        }
        set
        { 
            OnPropertyChanged( "Description" );
            Description = value;

        }
    }
}

}

EDIT I have added public class MedicationList : INotifyPropertyChanged

Upvotes: 6

Views: 10688

Answers (6)

Eldlabs
Eldlabs

Reputation: 552

You need to inherent BaseViewModel.

public class MedicationList : BaseViewModel

Upvotes: 0

Jeppe Stig Nielsen
Jeppe Stig Nielsen

Reputation: 62002

There's a difference between a base class and an interface.

With a base class, the members are automatically inherited and one needs to do nothing (except if some members need an override). With an interface, the class does not inherit the interface members automatically; you have to introduce them in your class. If you don't the compiler will complain.

INotifyPropertyChanged is an interface.

Upvotes: 0

Sergey Berezovskiy
Sergey Berezovskiy

Reputation: 236278

You should implement INotifyPropertyChanged interface, which has single PropertyChanged event declared. You should raise this event if some of object's properties changed. Correct implementation:

public class MedicationList : INotifyPropertyChanged
{
    private string _description; // storage for property value

    public event PropertyChangedEventHandler PropertyChanged;

    public string Description
    {
        get { return _description; }
        set
        {
            if (_description == value) // check if value changed
                return; // do nothing if value same

            _description = value; // change value
            OnPropertyChanged("Description"); // pass changed property name
        }
    }

    // this method raises PropertyChanged event
    protected void OnPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null) // if there is any subscribers 
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }
}

Upvotes: 7

JeremiahDotNet
JeremiahDotNet

Reputation: 910

You need the actual code the interface implements inside of your class.

/// <summary>
/// Public event for notifying the view when a property changes.
/// </summary>
public event PropertyChangedEventHandler PropertyChanged;

/// <summary>
/// Raises the PropertyChanged event for the supplied property.
/// </summary>
/// <param name="name">The property name.</param>
internal void OnPropertyChanged(string name)
{
    PropertyChangedEventHandler handler = PropertyChanged;
    if (handler != null)
    {
        handler(this, new PropertyChangedEventArgs(name));
    }
}

Upvotes: 1

JaredPar
JaredPar

Reputation: 755239

This method needs to be defined by your type to raise the INotifyPropertyChanged::PropertyChanged event

public PropertyChangedEventHandler PropertyChanged;

...

private void OnPropertyChanged(string propertyName) {
  var saved = PropertyChanged;
  if (saved != null) { 
    var e = new PropertyChangedEventArgs(propertyName);
    saved(this, e);
  }
}

Upvotes: 0

Ondrej Svejdar
Ondrej Svejdar

Reputation: 22084

I bet you want to do something like this:

public class MedicationList : INotifyPropertyChanged {
  public int MedicationID { get; set; }
  private string m_Description;

  public string Description {
    get { return m_Description; }
    set {
      m_Description = value;
      OnPropertyChanged("Description");
    }
  }

  private void OnPropertyChanged(string propertyName) {
    if (string.IsNullOrEmpty(propertyName))
      throw new ArgumentNullException("propertyName");

    var changed = PropertyChanged;
    if (changed != null) {
      changed(this, new PropertyChangedEventArgs(propertyName));
    }
  }

  public event PropertyChangedEventHandler PropertyChanged;
}

Upvotes: 3

Related Questions