導航多對多關系Django

Question

我需要獲取給定菜單的項目名稱和數量列表。 我如何查詢和返回帶有所需列的QuerySet？

我只獲得菜單列表，但仍然無法獲得數量。 我應該做多個查詢還是嘗試使用原始SQL

class Item(models.Model):
    name = models.CharField(max_length=20)

class Meals(models.Model):
    name = models.CharField(max_length=50)
    ingredients = models.ManyToManyField(Item, through='MealRecipe')


 class Menu(models.Model):
     name = models.CharField(max_length=50)
     meals = models.ManyToManyField(Meals,through='CompMenu')


 class CompMenu(models.Model):
     TYPE_COMP = (
         ('B', 'Breakfast'),
         ('L', 'Lunch'),
         ('D', 'Dinner')
     )
     menu = models.ForeignKey(Menu)
     meal = models.ForeignKey(Meals)
     type = models.CharField(max_length=1, choices=TYPE_COMP)

class MealRecipe(models.Model):
    meal = models.ForeignKey(Meal)
    item = models.ForeignKey(Item)
    qty = models.IntegerField()

Answer 1

如果我記得改正，可以通過以下方式獲取name和qty ：

menu = Menu.objects.filter(name='some_name')
meals_of_menu = menu[idx].meals.all()

receipes = MealRecipe.objects.filter(meal__in=meals_of_menu)
for receipe in receipes:
    name = receipe.item.name
    qty = receipe.qty

Answer 2

如果我MealRecipe.objects.filter(meal__menu=some_menu_instance).distinct()話， MealRecipe.objects.filter(meal__menu=some_menu_instance).distinct()應該可以做到。 或者，如果您擁有菜單ID而不是實例， meal__menu__id=some_id 。這只是一個標准的交叉關系查詢。