How to access UI elements in multiple threads? - wpf

Question

I had a standard foreach loop which I later turned into a Parallel.Foreach(). However in my loop I have areas where I access the UI elements and get and set the UI elements info.
So when I run it I get an error that I cannot access the element as another thread has access to it. There are multiple elements I need to access and the x:Name are stored in the list.
How do I get past this?
Parallel.ForEach(calculatedTestVariables, variable =>
{
string idName = "id_" + variable.id;
var textBox = this.FindName(idName) as TextBox; //need the text from this TextBox
//some calculations
int x = 1 + 2 + 3 + 4
textBox.Text = x.toString();
});

Answer 1

To do this, you need data binding. You may follow such a way,
First create your view model and update your properties:
public class MainViewModel : BindableBase
{
private string m_TextProgress;
public string TextProgress
{
get { return m_TextProgress; }
set { SetProperty(ref m_TextProgress, value); }
}
public void Run()
{
List<Variable> calculatedTestVariables = new List<Variable>();
for (int i = 0; i < 5000; i++)
{
Variable item = new Variable();
item.id = i;
calculatedTestVariables.Add(item);
}
Parallel.ForEach(calculatedTestVariables, variable =>
{
string idName = "id_" + variable.id;
//some calculations
int x = 1 + 2 + 3 + 4;
TextProgress = "" + variable.id + x;
});
}
}
Set your DataContext
<Window.DataContext>
<local:MainViewModel />
</Window.DataContext>
<Grid>
<StackPanel>
<TextBlock
Width="120"
Height="30"
HorizontalAlignment="Left"
VerticalAlignment="Top"
Text="{Binding TextProgress, UpdateSourceTrigger=PropertyChanged, Mode=OneWay}" />
<Button
Width="120"
Height="30"
HorizontalAlignment="Left"
VerticalAlignment="Top"
Click="Button_Click"
Content="Calculate" />
</StackPanel>
</Grid>
and call your Run method from GUI side