Django模型上的动态字段

Question

I have my models.py

class Restaurant(models.Model):
    name = models.CharField(max_length=100, blank=False)
    opening_time = models.TimeField(blank=False)
    closing_time = models.TimeField(blank=False)

    def __str__(self):
        return self.name

    @property
    def is_open(self):
        return (
            True
            if self.opening_time <= datetime.now().time() < self.closing_time
            else False
        )

And, my serializer.py:

class RestaurantSerializer(serializers.HyperlinkedModelSerializer):
    class Meta:
        model = Restaurant
        fields = ('pk', 'name', 'opening_time', 'closing_time')

I have the is_open property in the model that checks if the restaurant is open. How can I have the is_open property logic run and update this field, when the object is retrieved using a query on when the user makes a GET request to the serializer API.

Right now, it works when the object is created. Is there a retrieve method on the model where I can put this logic?

I was thinking about using Celery to check if it's open, but it sounds like an overkill solution. Of course, I would like this change to affect the serializer, so it should be something done on the model, I would think.

Answer 1

You can add is_open as a SerializerMethodField:

class RestaurantSerializer(serializers.HyperlinkedModelSerializer):
    is_open = serializers.SerializerMethodField()

    class Meta:
        model = Restaurant
        fields = ('pk', 'name', 'opening_time', 'closing_time', 'is_open')

    def get_is_open(self, instance):
        return instance.is_open