How to filter queryset based on related models?

Question

I would like to get queryset of recipes based on groceries queryset. In my models.py I have a grocery model

class Grocery(models.Model):
    title = models.CharField(max_length=100)
    picture = models.ImageField(upload_to='pictures/groceries', blank=True)
    category = models.ForeignKey(Category, unique=False)

I have an recipe model:

class Recipe(models.Model):
    title = models.CharField(max_length=100)
    chef = models.ForeignKey(settings.AUTH_USER_MODEL, unique=False, related_name='chefs_recipe')
    text = models.TextField()
    picture = models.ImageField(upload_to='pictures/recipes/title-photos', blank=True)

I have an ingredient model which is basically a many to many junction table

class Ingredient(models.Model):
    recipe = models.ForeignKey(Recipe, unique=False, related_name='recipeingredients')
    grocery = models.ForeignKey(Grocery, unique=False)
    quantity = models.DecimalField(max_digits=10, decimal_places=2)
    PRIORITY = (
        ('high', 'inevitable'),
        ('average', 'replaceble'),
        ('low', 'flavoring')
    )
    priority = models.CharField(max_length=20, choices=PRIORITY)

and I have a queryset of groceries selected by user.

How can I get a queryset of recipes which could be cooked with users groceries? That means I want all recipes which HIGH PRIORITY ingredient.grocery are contained in groceris queryset.

def get_queryset(self):
   groceries = Grocery.objets.filter(some_filter)
   recipes = ?

All I could think was a loop in which I will check recipe by recipe but it seems mostly inefficient when recipe table will contain lot of data.

any idea?

Answer 1

I think this solve your problem:

def get_queryset(self):
   groceries = Grocery.objets.filter(some_filter)
   recipes = Recipe.objects.filter(pk__in=Ingredient.objects.filter(priority='high',grocery__in=groceries).values_list('recipe_id', flat=True).distinct())