//更新 Instructor 實體的 Courses 導覽屬性
private void UpdateInstructorCourses(string[] selectedCourses, Instructor instructorToUpdate)
{
if (selectedCourses == null)
{
instructorToUpdate.CourseAssignments = new List <CourseAssignment>();
return;
}
var selectedCoursesHS = new HashSet <string>(selectedCourses);
var instructorCourses = new HashSet <int>
(instructorToUpdate.CourseAssignments.Select(c => c.Course.CourseID));
foreach (var course in _context.Courses)
{
if (selectedCoursesHS.Contains(course.CourseID.ToString()))
{
if (!instructorCourses.Contains(course.CourseID))
{
instructorToUpdate.CourseAssignments.Add(new CourseAssignment {
InstructorID = instructorToUpdate.ID, CourseID = course.CourseID
});
}
}
else
{
if (instructorCourses.Contains(course.CourseID))
{
CourseAssignment courseToRemove = instructorToUpdate.CourseAssignments.FirstOrDefault(i => i.CourseID == course.CourseID);
_context.Remove(courseToRemove);
}
}
}
}
public async Task <IActionResult> DeleteConfirmed(int id)
{
var genre = await _context.Genres.FindAsync(id);
_context.Remove(genre);
await _context.SaveChangesAsync();
return(RedirectToAction(nameof(Index)));
}