Wpf – INotifyPropertyChanged or INotifyCollectionChanged with DataTable

bindinginotifycollectionchangedinotifypropertychangedwpf

Hi i am having some troube with DataTables. So What i need is to detect whenever i change any cell in the DataGrid of the DataTable that is binded.

How to do it? With INotifyPropertyChanged or with INotifyCollectionChanged?

Note: I am trying with INotifyPropertyChanged but it only detects when i set some value in the DataTable, and never when i change any value of any cell in the DataGrid, i already have tried OneWay and TwoWay but nothing happens.

Thanks in advance!

Best Answer

The datagrid would be bound to a list of objects. If you want the grid to update when individual object properties change, than each contained object must implement the INotifyPropertyChanged interface.

The INotifyCollectionChanged is an interface that the collection should implement, and are for notifications of addition and removal events.

See the section "How to implement collections" on this page.

Here's a way to approach your problem:

Create a new class that exposes the properties currently held in each DataRow. On this class implement INotifyPropertyChanged.
Instead of a DataTable, use an ObservableCollection<T> or your new class.

ObservableCollection already implements INotifyCollectionChanged, so this saves you the effort of implementing it yourself.

Related Solutions

R – INotifyPropertyChanged and INotifyCollectionChanged in F# using WPF

You can use an ObservableCollection which will implements INotifyCollectionChanged for you. The F# looks something like this:

open System
open System.Collections.ObjectModel
open System.Windows
open System.Windows.Controls
open System.Windows.Threading

[<EntryPoint; STAThread>]
let Main args =

    let data    = ObservableCollection [0 .. 9]
    let list    = ListBox(ItemsSource = data)    
    let win     = Window(Content = list, Visibility = Visibility.Visible)    
    let rnd     = Random()

    let callback = 
        EventHandler(fun sender args -> 
            let idx = rnd.Next(0, 10)
            data.[idx] <- rnd.Next(0, 10) 
            )

    let ts  = TimeSpan(1000000L)
    let dp  = DispatcherPriority.Send
    let cd  = Dispatcher.CurrentDispatcher   

    let timer   = DispatcherTimer(ts, dp, callback, cd) in timer.Start()    
    let app     = Application() in app.Run(win)

Unfortunately Reflector shows that System.Windows.Controls.ItemsControl.OnItemCollectionChanged method removes the selection when it is called, so you may need to work around this default behaviour.

You can also implement INotifyPropertyChanged like so:

open System.ComponentModel

type MyObservable() =

    let mutable propval = 0.0
    let evt             = Event<_,_>()   

    interface INotifyPropertyChanged with

        [<CLIEvent>]
        member this.PropertyChanged = evt.Publish

    member this.MyProperty

        with get()  = propval
        and  set(v) = propval <- v
                      evt.Trigger(this, PropertyChangedEventArgs("MyProperty"))

Implementing INotifyCollectionChanged would work similarly.

best of luck,

Danny

C# – Binding when a button is pressed (Explicit binding) has always BindingExpression at null

Alright, after thinking a little more I noticed that :

 BindingExpression be = this.txtUrl.GetBindingExpression(TextBox.TextProperty);
 be.UpdateTarget();

Has something illogical because I do not want to update the Target but the source. I have simply changed be.Updatetarget() to be.UpdateSource(); and everything worked with this XAML:

 <TextBox x:Name="txtUrl" Text="{Binding Path=Url, UpdateSourceTrigger=Explicit}">...

Thank you to everybody who have helped me in the process to solve this problem. I have added +1 to everybody! Thanks

Best Answer

Related Solutions

R – INotifyPropertyChanged and INotifyCollectionChanged in F# using WPF

C# – Binding when a button is pressed (Explicit binding) has always BindingExpression at null

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