How to Set Focus to a WPF TextBox from the View Model?

Set the TextBox focus from the view model in WPF

Question:

I encountered a problem when I tried to set the Textbox control from the view model of the WPF application. After clicking on a button, I need to display a message to the user, and then set the cursor to the Textbox control, but the cursor is not set. The following is the relevant code:

Answer:

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);
}

You need to consider a few possible questions:

Reference UI in the view model:

Under normal circumstances, UI elements are not recommended in the view model. Instead, please consider using other methods, such as additional attributes or data binding.

1. .NET source code debugging: In order to eliminate focus issues, it is very valuable to enable the .NET source code debugging. This allows you to gradually execute the code and accurately find out where the focus is not set correctly.

2. Add attribute solution:

   A simple method is to use additional attributes to track and set the focus from the view model. The following is an example:

3. Then you can bind this attribute to your view model in the view:

   This revised answer maintains the original image and formatting while rewording the text for improved clarity and flow. The code examples are unchanged.

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