John D John D - 1 month ago 21
Python Question

Django Serializer Method Field

Can't seem to find the right google search for this so here it goes:

I have a field in my serializer:

likescount = serializers.IntegerField(source='post.count', read_only=True)


which counts all the related field "post".

Now I want to use that field as part of my method:

def popularity(self, obj):
like = self.likescount
time = datetime.datetime.now()
return like/time


Is this possible?

Answer

assuming post.count is being used to measure the number of likes on a post and you don't actually intend to divide an integer by a timestamp in your popularity method, then try this:

use a SerializerMethodField

likescount = serializers.SerializerMethodField('get_popularity')

def popularity(self, obj):
    likes = obj.post.count
    time = #hours since created
    return likes / time if time > 0 else likes

however I would recommend making this a property in your model

in your model:

@property
def popularity(self):
    likes = self.post.count
    time = #hours since created
    return likes / time if time > 0 else likes

then use a generic Field to reference it in your serializer:

class ListingSerializer(serializers.ModelSerializer):
    ...
    popularity = serializers.Field(source='popularity')