Bad performance

[Vladyslav]

JournalWebApi/DJournalWebApi/Controllers/ImportController.cs

Lines 31 to 58 in c2fce42

             data.ForEach(gr => 
                  { 
                      Group t = _context.Groups.FirstOrDefault(gr1 => gr1.OldName == gr.oldname || gr1.NewName == gr.newname); 
                      bool exist = true; 
                      if (t == null) 
                      { 
                          t = new Group() 
                          { 
                              OldName = gr.oldname, 
                              NewName = gr.newname, 
                          }; 
                          exist = false; 
                      } 
                      t.Students = gr.students.Select(st => 
                             { 
                                 if (_context.Students.FirstOrDefault(st1 => st1.Number == st.number) is Student s) 
                                 { 
                                     return s; 
                                 } 
                                 return new Student 
                                 { 
                                     Name = st.name, 
                                     Number = st.number 
  
                                 }; 
                             }).ToList(); 
                      if (!exist) _context.Groups.Add(t); 
                      _context.SaveChanges(); 

Кол-во запросов к базе стремиться к бесконечности.