added the correct migration for dish_ratings FK-binding

server/backend/migration/20240311000000.go

@@ -7,13 +7,35 @@ import (
 
 // migrate20240311000000
 // made sure that dishes have the correct indexes
+// changed how `dish_ratings` is bound to `dish`
 func migrate20240311000000() *gormigrate.Migration {
 	return &gormigrate.Migration{
 		ID: "20240311000000",
 		Migrate: func(tx *gorm.DB) error {
+			// make sure that dish_ratings are FK-bound to dishes
+			if err := tx.Exec(`alter table dish_rating
+				add constraint dish_rating_dish_dish_fk
+				foreign key (dishID) references dish (dish)
+				on delete cascade;`).Error; err != nil {
+				return err
+			}
+			// because dishes already have a cafeteria, storing this again is not necessary
+			if err := tx.Exec(`alter table dish_rating drop column cafeteriaID`).Error; err != nil {
+				return err
+			}
+			// uniqueness
 			return tx.Exec("create unique index dish_name_cafeteriaID_uindex on dish (name, cafeteriaID)").Error
 		},
 		Rollback: func(tx *gorm.DB) error {
+			// make sure that dish_ratings are FK-bound to dishes
+			if err := tx.Exec(`alter table dish_rating drop constraint dish_rating_dish_dish_fk`).Error; err != nil {
+				return err
+			}
+			// because dishes already have a cafeteria, storing this agiain is not nessesary
+			if err := tx.Exec(`alter table dish_rating add column cafeteriaID int not null`).Error; err != nil {
+				return err
+			}
+			// uniqueness
 			return tx.Exec("drop index dish_name_cafeteriaID_uindex on dish").Error
 		},
 	}