Trigger like solution for DataGridCell using DataTriggerBehavior (Avalonia.Xaml.Interactivity)

[IgorSakovich]

Hello! Please tell me how I can implement trigger for each DataGrid cell related to Age property throw ChangePropertyAction ? I have not yet been able to implement this through table styles. Is this the right decision? Thanks!

<DataGrid Name="MyDataGrid" 
				  Items="{Binding Persons}" 
				  AutoGenerateColumns="False">
			
				<!--<i:Interaction.Behaviors>
				<ia:DataTriggerBehavior
					Binding="{Binding Age}"
					ComparisonCondition="Equal"
					Value="13">
					<ia:ChangePropertyAction
						TargetObject="MyDataGrid"
						PropertyName="Background"
						Value="Red" />
				</ia:DataTriggerBehavior >
			</i:Interaction.Behaviors>-->

			<DataGrid.Columns>
				<DataGridTextColumn Header="Forename"	Binding ="{Binding FirstName}"/>
				<DataGridTextColumn Header="Surname"	Binding="{Binding LastName}" />
				<DataGridTextColumn Header="Age"		Binding="{Binding Age}"/>
			</DataGrid.Columns>
		</DataGrid>

[maxkatz6]

I think you can attach a behavior to the control using styles. @wieslawsoltes does it work with stable branch and is there any example of that?

So, in your case you would need to set CellClasses on the right column (let's say "ageColumn").
And with selector "DataGridCell.ageColumn" you can add your behavior as an attached property in the selector.

[wieslawsoltes]

I think you can attach a behavior to the control using styles. @wieslawsoltes does it work with stable branch and is there any example of that?

Example: https://github.com/wieslawsoltes/AvaloniaBehaviors/blob/f235559d91acb9a2b051ef40a4ae1bb9a0752446/samples/DragAndDropSample/Views/MainWindow.axaml#L84-L90

It works with stable branch 0.10.x

[Kerminator1973]

Thanks for the useful hints! As I am looking for the same answer I have reconstructed the code that is close to your hints:

<Window.Styles>
	<Style Selector="DataGridCell.statusColumn">
		<Setter Property="FontSize" Value="24"/>
		<Setter Property="(int:Interaction.Behaviors)">
			<int:BehaviorCollectionTemplate>
				<int:BehaviorCollection>
					<ia:DataTriggerBehavior Binding="{Binding Status}" ComparisonCondition="Equal" Value="Rejected">
						<ia:ChangePropertyAction TargetObject="DataGridCell" PropertyName="Background" Value="Yellow" />
					</ia:DataTriggerBehavior>
				</int:BehaviorCollection>
			</int:BehaviorCollectionTemplate>
		</Setter>
	</Style>
</Window.Styles>
...
<DataGrid AutoGenerateColumns="False" Margin="10"
		  Items="{Binding Banknotes}" SelectedItem="{Binding SelectedBanknote}">
	<DataGrid.Columns>
		<DataGridTextColumn Header="{x:Static p:Resources.NoteId}" Binding="{Binding Id}" />
		<DataGridTextColumn Header="{x:Static p:Resources.NoteCurrency}" Binding="{Binding Currency}" />
		<DataGridTextColumn Header="{x:Static p:Resources.NoteDenomination}" Binding="{Binding Denomination}" />
		<DataGridTextColumn Header="{x:Static p:Resources.Status}" Binding="{Binding Status}" CellStyleClasses="statusColumn" />
	</DataGrid.Columns>
</DataGrid>

Let me explain my intentions: I want to attach the behaviour for replacing the Background property to every DataGridCell object that has a "statusColumn" class. I use the BehaviorCollection because it attaches a behaviour to each object according to the selector.

The code almost works. The only problem I have is that the binding doesn't use the DataGridCell's DataContext (the element of the ObservableCollection from the ViewModel), but it uses the DataContext of the whole View/Window (ViewModel). Is there any way to specify that I need the DataGridCell's DataContext and not the View's DataContext?

[Kerminator1973]

Thank you very much for your great advice! I’ve just changed Brushed.Green to null and I got the desired behaviour (see https://github.com/Kerminator1973/Avalonia.DataGridExample).

[nasterhe]

Thank you very much for your great advice! I’ve just changed Brushed.Green to null and I got the desired behaviour (see https://github.com/Kerminator1973/Avalonia.DataGridExample).

@Kerminator1973 nice work,However, when the reject Status is modified, the color does not follow the change.

[Kerminator1973]

@Kerminator1973 nice work,However, when the reject Status is modified, the color does not follow the change.

I'm really sorry to have taken so long to reply, please give me a little more time. I will try to reproduce the problem and resolve it.

[Kerminator1973]

@Kerminator1973 nice work,However, when the reject Status is modified, the color does not follow the change.

Well, I changed the code of the demo application. Please have a look at the latest commit (58ec696c...). After two seconds, the third banknote (Id=3) changes it's status field from "Rejected" to "Jammed". I used an instance of DispatcherTimer to sleep for 2 seconds in the MainWindow class. In the Timer_Tick method, I change the value of the third note to "Jammed". Please have a look at the model - it inherits the INotifyPropertyChanged interface. It allows you to update the DataGrid in the MainWindow. Does it make sense to you?

[nasterhe]

@Kerminator1973 nice work,However, when the reject Status is modified, the color does not follow the change.

Well, I changed the code of the demo application. Please have a look at the latest commit (58ec696c...). After two seconds, the third banknote (Id=3) changes it's status field from "Rejected" to "Jammed". I used an instance of DispatcherTimer to sleep for 2 seconds in the MainWindow class. In the Timer_Tick method, I change the value of the third note to "Jammed". Please have a look at the model - it inherits the INotifyPropertyChanged interface. It allows you to update the DataGrid in the MainWindow. Does it make sense to you?

Thanks.I I've found an easier way to do it, please see: #17790

[timunie]

Accepted answer in this comment and following, for anyone interested: #8121 (reply in thread)