public IActionResult DeleteCourse(string id, int courseId) { ViewData["Id"] = id; //deleting all presentations Course course = repository.Courses .FirstOrDefault(c => c.CourseId == courseId); while (course.Presentations.Count() > 0) { Presentation p = course.Presentations.FirstOrDefault(); Presentation deletedP = repository.DeletePresentation(p.PresentationId); } Course deletedCourse = repository.DeleteCourse(courseId); if (deletedCourse != null) { TempData["messageIn"] = $"Course: '{deletedCourse.Title}' has been deleted!"; } return(RedirectToAction("Index", new{ id, status = "Private", sort = "Title", order = "asc" })); }