Set focus on TextBox in WPF from view model

How to Set Focus on TextBox in WPF from View Model

Have you ever encountered the problem of setting the focus on a TextBox control in WPF from your view model? It can be frustrating when you want to direct the user's attention to a specific input field, but the cursor refuses to cooperate. In this blog post, we will explore a common issue with setting focus on a TextBox control in WPF from the view model and provide you with an easy solution.

The Problem

Let's start by discussing the issue at hand. Suppose you have a TextBox control and a Button in your view, and you need to set the focus on the TextBox when a certain condition is met. However, despite your best efforts, the cursor stubbornly refuses to land in the TextBox.

The Code

Here's an example of the code in your view model:

if (companyref == null)
{
    var cs = new Lipper.Nelson.AdminClient.Main.Views.ContactPanels.CompanyAssociation(); 

    MessageBox.Show("Company does not exist.", "Error", MessageBoxButton.OK, MessageBoxImage.Exclamation);

    cs.txtCompanyID.Focusable = true;
    System.Windows.Input.Keyboard.Focus(cs.txtCompanyID);
}

The XAML

To provide a complete understanding of the issue, let's also take a look at the relevant XAML code:

<igEditors:XamTextEditor Name="txtCompanyID" 
                        KeyDown="xamTextEditorAllowOnlyNumeric_KeyDown"
                        ValueChanged="txtCompanyID_ValueChanged"
                        Text="{Binding Company.CompanyId, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
                        Width="{Binding ActualWidth, ElementName=border}"
                        Grid.Column="1" Grid.Row="0"
                        VerticalAlignment="Top"
                        HorizontalAlignment="Stretch"
                        Margin="0,5,0,0"
                        IsEnabled="{Binding Path=IsEditable}"/>

<Button Template="{StaticResource buttonTemp1}"
        Command="{Binding ContactCommand}"
        CommandParameter="searchCompany"
        Content="Search"
        Width="80"
        Grid.Row="0" Grid.Column="2"
        VerticalAlignment="Top"
        Margin="0"
        HorizontalAlignment="Left"
        IsEnabled="{Binding Path=IsEditable}"/>

The Solution

To set the focus on the TextBox control from the view model, we need to follow these steps:

1. Ensure that the TextBox is focusable by setting the Focusable property to true. In this case, txtCompanyID.Focusable = true;.

2. Use the Keyboard.Focus method to set the focus on the TextBox. In this case, System.Windows.Input.Keyboard.Focus(cs.txtCompanyID);.

By following these two steps, you should be able to set the focus on the TextBox control successfully.

Engage with Us!

We hope this blog post has helped you understand how to set the focus on a TextBox control in WPF from the view model. If you have any questions or face any issues, please let us know in the comments below. We would love to hear your feedback and engage with you on this topic!

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