在Windows窗体上验证控件

Question

I have a windows from written in C# and wanted to verify that the data in each control (dropdown, textbox, etc) is not null before saving the data to a database. I have multiple forms like this in the application. How would I go about doing it? I am thinking I create boolean function.

Answer 1

You can write a simple method to loop through the controls in the form and check the control values.

    private bool CheckControls()
    {
        foreach (Control ctrl in this.Controls)
        {
           //Write the code to check whether the control value is null
            //case: Testbox return true;
            //case: Dropdown return true;
            //case: Listbox return true;
            //..etc

        }
        return false;
    }

Answer 2

use an ErrorProvider. Put the error provider on the form and then you can have a utility function that can handle all the controls with one call. I used the following code for making sure something was entered in a textbox, you can expand upon this method.

Utility method that handled required fields, I used the tag field to hold the specific error message since I wasn't using it for anything else and it was quick and easy.

public static void TextBoxRequired_Validating(object sender, CancelEventArgs e, ErrorProvider errorProvider)
{
    var textbox = (TextBox)sender;
    var valid = !String.IsNullOrWhiteSpace(textbox.Text);
    e.Cancel = !valid;
    errorProvider.SetError(textbox, (valid ? string.Empty : textbox.Tag.ToString()));
}

The event handler calling the utility method

void txtName_Validating(object sender, CancelEventArgs e)
{
    ControlUtility.TextBoxRequired_Validating(sender, e, errorProvider1);
}