Set focus to text box from code behind after validation the inputs in asp.net web application

Question

What I want to do is to validate the given input by the user and then set a focus on the invalid input in text box.

My save button function is given below.

protected void btnSave_OnClick(object sender, EventArgs e)
{
    try
    {          
        if (ValidateForm())
        {
            Users objUser = new Users();
            objUser.Username = this.txtUsername.Text;
            objUser.Password = this.txtPassword.Text;
            objUser.Add();

            this.labelMessage.Text = "User has been saved successfully";
        }
    }
    catch (Exception ex)
    {
        Monitoring.WriteException(ex);
    }
}

Validation function to validate the given input is not null or empty.

private bool ValidateForm()
{
    bool isvalidate = true;

    try
    {
        string username = this.txtUsername.Text;
        string password = this.txtPassword.Text;

        if (username == "" || username == string.Empty)
        {
            this.labelMessage.Text = "Please enter username";
            this.txtUsername.Focus();
            isvalidate = false;
        }
        else if (password == "" || password == string.Empty)
        {
            this.labelMessage.Text = "Please enter password";
            this.txtPassword.Focus();
            isvalidate = false;
        }
    }
    catch (Exception ex)
    {
        Monitoring.WriteException(ex);
    }
    return isvalidate;
}

The problem is the I am unable to set focus to any textbox after validation. Anyone know where I am wrong? Or there is any other better way? I have searched a lot but most of them setting the focus on Page load (Post back). I want to do it from code behind.

Solution

Try the following Code. Use this code in your code behind. And pass your textbox id to SetFocus function. It will surely solve your problem.

Replace this code

this.txtUsername.Focus();

With this code

ScriptManager.GetCurrent(this.Page).SetFocus(this.txtUsername);

Given below is a tested code.

private bool ValidateForm()
{
    bool isvalidate = true;

    try
    {
        string username = this.txtUsername.Text;
        string password = this.txtPassword.Text;

        if (username == "" || username == string.Empty)
        {
            this.labelMessage.Text = "Please enter username";
            ScriptManager.GetCurrent(this.Page).SetFocus(this.txtUsername);
            isvalidate = false;
        }
        else if (password == "" || password == string.Empty)
        {
            this.labelMessage.Text = "Please enter password";
            ScriptManager.GetCurrent(this.Page).SetFocus(this.txtPassword);
            isvalidate = false;
        }
    }
    catch (Exception ex)
    {
        Monitoring.WriteException(ex);
    }
    return isvalidate;
}