protected void Students_RowUpdating(object sender, GridViewUpdateEventArgs e)
        {
            GridViewRow row         = (GridViewRow)this.Students.Rows[e.RowIndex];
            TextBox     idContainer = (TextBox)row.Cells[0].Controls[0];
            TextBox     markValue   = (TextBox)row.Cells[4].Controls[0];
            double      value;

            if (double.TryParse(markValue.Text, out value))
            {
                var markDTO = new AddMarkDTO()
                {
                    StudentId = idContainer.Text, Value = value
                };
                var teacherId = Context.User.Identity.GetUserId();

                var ev = new AddMarksEventArgs(teacherId, markDTO);
                this.InsertMarks?.Invoke(sender, ev);

                if (this.Model.IsSuccess)
                {
                    this.Message.ShowSuccess("Mark added.");
                    this.Classes_SelectedIndexChanged(sender, e);
                }
                else
                {
                    this.Message.ShowError(this.Model.ErrorMessage);
                }
            }
        }
 public AddMarksEventArgs(string teacherId, AddMarkDTO mark)
 {
     this.TeacherId = teacherId;
     this.Mark      = mark;
 }