使用Django模型系统进行评分

Question

class User(models.Model):
    username = models.CharField(max_length=150)
    email = models.EmailField(max_length=150)

class Recipes(models.Model):
    title = models.CharField(max_length=150)
    user = models.ForeignKey(User, related_name='user', on_delete=models.CASCADE, null=True)
    created = models.DateTimeField(auto_now=True, auto_now_add=False)
    updated = models.DateTimeField(auto_now=False, auto_now_add=True)

class FavoriteRecipes(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE, null=True)
    recipe = models.ForeignKey(Recipes, on_delete=models.CASCADE, null=True)

class FavoriteChef(models.Model): 
    user = models.ForeignKey(User, related_name='user', on_delete=models.CASCADE)
    favorite = models.ForeignKey(User, related_name='favorite', on_delete=models.CASCADE)

I am trying to create a rating system to recipes and users. I am not sure if this is the best approach or not, but his are my questions:

1. how I count the ammount of recipes liked by different user, example:

   • user 1 liked recipe 1
   • user 2 liked recipe 1
   • recipe 1 is liekd by 2.

2. how to limit the user from voting may times using this approach, since django generates its own pk entries like this can exists:

   • pk:1 user 1 liked recipe 1

   • pk:2 user 1 liked recipe 1

and thanks

Answer 1

you could limit the number of votes with:

if FavoriteRecipes.objects.filter(recipe=Recipes, user=User).exists():
  #do not update
else:
    #save vote

then you could count the votes with:

count= FavoriteRecipes.objects.filter(recipe=Recipe).count()