Using of Inotifypropertychanged

using of INotifyPropertyChanged

You need INotifyPropertyChanged if you want a wpf form to be automatically updated when a property changes through code. Also some controllers might want to know if edits have been made in order to enable/disable a save-button, for instance. You also might be displaying the same property on different views; in this case INotifyPropertyChanged helps to immediately update the other view when you edit a property.

If you think that your form behaves well without INotifyPropertyChanged, then you can drop it.

Note that binding works even without INotifyPropertyChanged. See: Why does the binding update without implementing INotifyPropertyChanged?

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I would implement the properties like this. In some rare cases it can help to avoid endless circular updates. And it is more efficient by the way.

 private string _firstName;
 public string StudentFirstName
 {
     get { return _firstName; }
     set
     {
         if (value != _firstName) {
             _firstName = value;
             OnPropertyChanged("StudentFirstName");
         }
     }
 }

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Starting with C#6.0 (VS 2015), you can implement OnPropertyChanged like this:

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

Implementing INotifyPropertyChanged - does a better way exist?

Without using something like postsharp, the minimal version I use uses something like:

public class Data : INotifyPropertyChanged
{
    // boiler-plate
    public event PropertyChangedEventHandler PropertyChanged;
    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }
    protected bool SetField<T>(ref T field, T value, string propertyName)
    {
        if (EqualityComparer<T>.Default.Equals(field, value)) return false;
        field = value;
        OnPropertyChanged(propertyName);
        return true;
    }

    // props
    private string name;
    public string Name
    {
        get { return name; }
        set { SetField(ref name, value, "Name"); }
    }
}

Each property is then just something like:

private string name;
public string Name
{
    get { return name; }
    set { SetField(ref name, value, "Name"); }
}

which isn't huge; it can also be used as a base-class if you want. The bool return from SetField tells you if it was a no-op, in case you want to apply other logic.

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or even easier with C# 5:

protected bool SetField<T>(ref T field, T value,
    [CallerMemberName] string propertyName = null)
{...}

which can be called like this:

set { SetField(ref name, value); }

with which the compiler will add the "Name" automatically.

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C# 6.0 makes the implementation easier:

protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
    PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

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...and now with C#7:

protected void OnPropertyChanged(string propertyName)
   => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));

protected bool SetField<T>(ref T field, T value,[CallerMemberName] string propertyName =  null)
{
    if (EqualityComparer<T>.Default.Equals(field, value)) return false;
    field = value;
    OnPropertyChanged(propertyName);
    return true;
}

private string name;
public string Name
{
    get => name;
    set => SetField(ref name, value);
}

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And, with C# 8 and Nullable reference types, it would look like this:

public event PropertyChangedEventHandler? PropertyChanged;

protected void OnPropertyChanged(string propertyName) => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));

protected bool SetField<T>(ref T field, T value, [CallerMemberName] string propertyName = "")
{
    if (EqualityComparer<T>.Default.Equals(field, value)) return false;
    field = value;
    OnPropertyChanged(propertyName);
    return true;
}

private string name;
public string Name
{
    get => name;
    set => SetField(ref name, value);
}

Why use INotifyPropertyChanged with bindings in WPF?

You don't need INotifyPropertyChanged if you only intend to use the binding to write to the property (as you have found out), but you do need it so that you can tell that someone else wrote to the property and update the displayed value accordingly.

To see what I 'm talking about, add a button to your window that when clicked directly changes the value of the bound property (not the corresponding attribute of the UI element bound to that property). With INotifyPropertyChanged, you will see the UI updating itself to the new value when you click the button; without it, the UI will still show the "old" value.

Using INotifyPropertyChanged and commands c# wpf?

The viewmodel class should implement INotifyPropertyChanged interface.

...
public class viewmodel : INotifyPropertyChanged
...

Keep the rest of your code as is.

Implement INotifyPropertyChanged in a Class

INotifyPropertyChanged is intended for view model classes, not for the views (or user controls) themselves. Therefore you don't normally need them in the views. You should use dependency properties instead, if you want to add fields to a user control.

See the example on UserControl:

/// <summary>
/// Identifies the Value dependency property.
/// </summary>
public static readonly DependencyProperty ValueProperty =
    DependencyProperty.Register(
        "Value", typeof(decimal), typeof(NumericUpDown),
        new FrameworkPropertyMetadata(MinValue, new PropertyChangedCallback(OnValueChanged),
                                      new CoerceValueCallback(CoerceValue)));

/// <summary>
/// Gets or sets the value assigned to the control.
/// </summary>
public decimal Value
{          
    get { return (decimal)GetValue(ValueProperty); }
    set { SetValue(ValueProperty, value); }
}

How does WPF know to use INotifyPropertyChanged when I bind to IEnumerable?

Even though your Data property is returned with the type of IEnumerable<IData>, the object itself is still a ObservableCollection<ObservableData>. WPF can just use the is or as operators to test whether any particular object implements INotifyPropertyChanged, regardless of the handle provided.

IEnumerable<IData> test = Data;
if (test is INotifyPropertyChanged) { 
    //This if block enters because test is really ObservableCollection<ObservableData>
    INotifyPropertyChanged test2 = (INotifyPropertyChanged)test;
}

Using INotifyPropertyChanged in a Class

You can't use automatic properties when trying to use this. You'll need to creating a backing store:

private string _someRandomText;
public string SomeRandomText {
    get { return _someRandomText; }
    set 
    {
        _someRandomText = value;
        NotifyPropertyChanged("SomeRandomText");
    }
}

How to bind INotifyPropertyChanged data with DataGrid in WPF?

Your window doesn't know, when you add or remove times to your Table. Instead of List<RowVM>, you should use ObservableCollection<RowVM>. It will invoke an event whenever an item is added or removed. This allows the GUI elements to realize they have to update themselves.

using INotifyPropertyChanged how to Click wpf button

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Last Edit: Here a link to a working solution for update a column in a ListView
(timer adding 1 min each second)

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First create a class to your relaycommand

using System;
using System.Diagnostics;
using System.Windows.Input;

public class RelayCommand : ICommand
    {
        readonly Action<object> _execute;
        readonly Predicate<object> _canExecute;

        #region Constructors

        /// <summary>
        /// Creates a new command.
        /// </summary>
        /// <param name="execute">The execution logic.</param>
        /// <param name="canExecute">The execution status logic.</param>
        public RelayCommand(Action<object> execute, Predicate<object> canExecute = null)
        {
            _execute = execute ?? throw new ArgumentNullException(nameof(execute));
            _canExecute = canExecute;
        }
        #endregion // Constructors

        #region ICommand Members
        [DebuggerStepThrough]
        public bool CanExecute(object parameter)
        {
            //For Vs 2015+ 
            return _canExecute?.Invoke(parameter) ?? true;
            //For Vs 2013-
            return _canExecute != null ? _canExecute.Invoke(parameter) : true;
        }

        /// <summary>
        /// Can execute changed event handler.
        /// </summary>
        public event EventHandler CanExecuteChanged
        {
            add => CommandManager.RequerySuggested += value;
            remove => CommandManager.RequerySuggested -= value;
        }

        public void Execute(object parameter)
        {
            _execute(parameter);
        }
        #endregion // ICommand Members
    }

then you can execute your command directly from your ViewModel

//with some validation to enable/disable button click

public virtual ICommand SearchCommand => new RelayCommand(o=> Search(), o=> Validation());

//without validation

 public virtual ICommand SearchCommand => new RelayCommand(o=> Search());

private void Search()
{

}

private bool Validation()
{

}

//using parametres
public virtual ICommand SearchCommand => new RelayCommand(Search);
private void Search(object parameter)
{

}

Your XAML

<Button Content="Search"  Command={Binding SearchCommand}  />

Example of ListView binding using MVVM

<ListView ItemsSource="{Binding Path=YourData}">
    <ListView.View>
         <GridView>
             <GridViewColumn Header="ID" Width="Auto" 
                  DisplayMemberBinding="{Binding ID}" >
             </GridViewColumn>
             <GridViewColumn DisplayMemberBinding="{Binding Name}" 
                  Header="Name" Width="100"/>
             <GridViewColumn DisplayMemberBinding="{Binding Price}" 
                  Header="Price" Width="100"/>
             <GridViewColumn DisplayMemberBinding="{Binding Author}" 
                  Header="Author" Width="100"/>
             <GridViewColumn DisplayMemberBinding="{Binding Catalog}" 
                  Header="Catalog" Width="100"/>
             <GridViewColumn>
                <GridViewColumn.CellTemplate>
                    <DataTemplate>
                      <Button Content="Search"  Command={Binding SearchCommand}  CommandParameter="{Binding Id}" />
                    </DataTemplate>
                </GridViewColumn.CellTemplate>
             </GridViewColumn>

           </GridView>
    </ListView.View>
</ListView>

Your ViewModel

public class MyViewModel: INotifyPropertyChanged
{
    //INotifyPropertyChanged implementation

    public ObservableCollection<MyData> MyData 
    {
        get { return _myData }
        set
        {
             _myData = value;
             OnPropertiChange(nameof(MyData));
        }
    }

    public virtual ICommand SearchCommand => new RelayCommand(o=> Search());

    private void Search()
    {
        //DoSamething

        MyData = new ObservableCollection<MyData>(ListOfMyData);
    }

}

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