WPF datagrid how to get access to the row click

Question

Seems that a WPF application I inherited has a DataGrid

<DataGrid x:Name="dataGrid" ItemsSource="{Binding AllTroubleCalls}" SelectedIndex="{Binding SelectedIndex}" 

I want to end up setting the Background color to yellow only if the Textbox contains text in it.

The text appears when I click on certain rows in the Datagrid

It seems that everything is based upon this "Binding"

  {Binding ... }   

I have a textbox that I added a Name to it

<TextBox ToolTipService.ShowDuration="120000" ToolTip="{Binding ThreatText}" Name="txtThreat" Text="{Binding ThreatText}"  
                 TextWrapping="Wrap" AcceptsReturn="True" 
                 VerticalScrollBarVisibility="Visible" HorizontalScrollBarVisibility="Visible"
                 Margin="3" Grid.Row="8"  Grid.Column="1" 
                 Grid.ColumnSpan="3" Grid.RowSpan="1" IsReadOnly="True" Height="30"/>

Show then when I am in a method I can "test" this and it works

  txtThreat.Background = new SolidColorBrush(Colors.Yellow); 

However, I'm not understanding why I cannot get a handle on the data changing from whatever row is clicked on in the Datagrid, that data then appears "magically" in many textboxes etc.. on the xaml page.

I gather that the "Binding" is handling this, but it is also MVVM 2 way binding ?

I have tried plastering so many breakpoints into so many methods but I can't seem to get any of them to show me how the data is changing on row click

Answer 1

There's a little too much going on in this question without the details. However, I can at least answer what I think is your goal. The easiest way to get a textbox to be yellow if there's a text in it is with a style:

    <TextBox >
        <TextBox.Style>
            <Style TargetType="TextBox">
                <Setter Property="Background" Value="Yellow"></Setter>
                <Style.Triggers>
                    <Trigger Property="Text" Value="">
                        <Setter Property="Background" Value="White"></Setter>
                    </Trigger>
                </Style.Triggers>
            </Style>
        </TextBox.Style>
    </TextBox>

As for figuring out how the data is changing... The Text displayed in your TextBox is bound to ThreatText. That means the text should change only when a property named ThreatText is changed in a class somewhere (your viewmodel). Have you tried putting a breakpoint on the setter for the ThreatText property? You can also put a breakpoint on the getter as well. It sounds like that when you click in the textbox/row, WPF updates the text in the UI, which means it's reevaluating the binding due to some change in ThreatText; this also means it'll hit the getter... you can check out the stack trace if it does to see what's going on.