How do I create property for objects in views.py in order to pass changed object to JS code

Question

I load "endless scroll" feed via AJAX and pagination. Before passing objects to JS code, I need to add property(or is it called attribute ?) to every object, which contains boolean, whether it was liked by current user or not. I thought it might work but something is wrong, because everything is getting undefined in frontend. How do I implement what I want in the right way? It's important to create property for every object, because later it's very practical just to fetch it the loop same as other data.

def loadmore(request,page_number):
    answers_to_questions_objects = Question.objects.filter(whom=request.user.profile).filter(answered=True).order_by('-answered_date')
    paginator = Paginator(answers_to_questions_objects,10)
    current_page = (paginator.page(page_number))
    for item in current_page:
        if request.user.profile in item.who_liked.all():
            item.liked = True
        else:
            item.liked = False
    print(current_page.liked)
    answers = serializers.serialize('json', current_page)
    data = {
        'answers': answers,

    }
    return Response(data)

Answer 1

serializers.serialize will only include the model fields. It won't include the attribute you set on model objects. Instead make a dict and add liked as a key into it.

import json

def loadmore(request,page_number):
    # I added prefetch, so it will avoid making queries inside your loop.
    answers_to_questions_objects = Question.objects.filter(whom=request.user.profile).filter(answered=True).order_by('-answered_date').prefetch_related('who_liked')
    paginator = Paginator(answers_to_questions_objects,10)
    current_page = (paginator.page(page_number))
    # I don't know why Question model objects are called answers.
    answers = []
    for item in current_page:
        item_dict = { 'whom': item.whom.name,
                      'id': item.id,
                      # Add the other required fields.
                      }
        if request.user.profile in item.who_liked.all():
            item_dict['liked'] = True
        else:
            item_dict['liked'] = False
        answers.append(item_dict)

    data = {
        'answers': json.dumps(answers),

    }
    return Response(data)

Update:

You should checkout django-rest-framework if you have to implement a lot of views like this. The serializer api and generic views that comes with it makes life a lot easier.

Answer 2

I need to add property(or is it called attribute ?) to every object, which contains boolean, whether it was liked by current user or not.

That fits better as a method on the model itself:

class Question(models.Model):
    """ A question on the site. """

    # …

    def liked_by_user(self, user):
        """ Is this question liked by `user`? """
        profile_users = {p.user for p in self.who_liked}
        liked = (user in profile_users)
        return liked

That way, the view has access to Question.liked_by_user(current_user) for any question instance.

You don't show a minimal complete verifiable example of your model definitions here, so I'll guess at a complete example:

# models.py

from django.contrib.auth.models import User
from django.db import models

class UserProfile(models.Model):
    """ The profile details for a user. """

    user = models.ForeignKey(User)


class Question(models.Model):
    """ A question on the site. """

    answered_date = models.DateField()

    def liked_by_user(self, user):
        """ Is this question liked by `user`? """
        profile_users = {p.user for p in self.who_liked}
        liked = (user in profile_users)
        return liked


class Like(models.Model):
    """ A flag that a user likes a question. """

    question = models.ForeignKey(Question, related_name='who_liked')
    user_profile = models.ForeignKey(UserProfile)