public static void DeleteChilds(this IRepository<School> sc, int schoolId)
{
var studentsRepo = new EfRepository<Student>(new SchoolContext());
var studentsFromSchool = studentsRepo.All().Where(x => x.School.SchoolId == schoolId).ToList();
foreach (Student student in studentsFromSchool)
{
studentsRepo.DeleteChilds(student.School.SchoolId);
studentsRepo.Delete(student.StudentId);
}
}