<Django object > is not JSON serializable

Question

I have the following code for serializing the queryset:

def render_to_response(self, context, **response_kwargs):

    return HttpResponse(json.simplejson.dumps(list(self.get_queryset())),
                        mimetype="application/json")

And following is my get_quersety()

[{'product': <Product: hederello ()>, u'_id': u'9802', u'_source': {u'code': u'23981', u'facilities': [{u'facility': {u'name': {u'fr': u'G\xe9n\xe9ral', u'en': u'General'}, u'value': {u'fr': [u'bar', u'r\xe9ception ouverte 24h/24', u'chambres non-fumeurs', u'chambres familiales',.........]}]

Which I need to serialize. But it says not able to serialize the <Product: hederello ()>. Because the list is composed of both django objects and dicts. Any ideas?

Subtype

Duplicated: https://mcmap.net/q/48302/-convert-django-model-object-to-dict-with-all-of-the-fields-intact – Visakhapatnam

Does this answer your question? Convert Django Model object to dict with all of the fields intact – Shandrashandrydan

Answer 1

simplejson and json don't work with django objects well.

Django's built-in serializers can only serialize querysets filled with django objects:

data = serializers.serialize('json', self.get_queryset())
return HttpResponse(data, content_type="application/json")

In your case, self.get_queryset() contains a mix of django objects and dicts inside.

One option is to get rid of model instances in the self.get_queryset() and replace them with dicts using model_to_dict:

from django.forms.models import model_to_dict

data = self.get_queryset()

for item in data:
   item['product'] = model_to_dict(item['product'])

return HttpResponse(json.simplejson.dumps(data), mimetype="application/json")

Alfonso

Now getting error --> 'NoneType' object has no attribute 'concrete_model' ... And using Django 1.4+ – Subtype

When the model has a datetime field, it does not work. – Bleary

that solution will trigger a lot of queries – Visakhapatnam

to use that directly in JS, just use the safe tage. https://mcmap.net/q/145169/-passing-objects-from-django-to-javascript-dom – Falstaffian

is there also a way back? besides, you will override the product in your solution if it happens that there are more items in data – Exhibitive

Answer 2

The easiest way is to use a JsonResponse.

For a queryset, you should pass a list of the the values for that queryset, like so:

from django.http import JsonResponse

queryset = YourModel.objects.filter(some__filter="some value").values()
return JsonResponse({"models_to_return": list(queryset)})

Richy

thanks for .values(), In my case, I just need to add .values() after filter – Precedency

Answer 3

I found that this can be done rather simple using the ".values" method, which also gives named fields:

result_list = list(my_queryset.values('first_named_field', 'second_named_field'))
return HttpResponse(json.dumps(result_list))

"list" must be used to get data as iterable, since the "value queryset" type is only a dict if picked up as an iterable.

Documentation: https://docs.djangoproject.com/en/1.7/ref/models/querysets/#values

Illiteracy

This worked well for me. Even though the error message suggests it's all in one big list, the list() is still apparently needed. – Pinch

Answer 4

From version 1.9 Easier and official way of getting json

from django.http import JsonResponse
from django.forms.models import model_to_dict


return JsonResponse(  model_to_dict(modelinstance) )

Ist

Answer 5

Another great way of solving it while using a model is by using the values() function.

def returnResponse(date):
    response = ScheduledDate.objects.filter(date__startswith=date).values()
    return Response(response)

Foxworth

Answer 6

Our js-programmer asked me to return the exact JSON format data instead of a json-encoded string to her.

Below is the solution.(This will return an object that can be used/viewed straightly in the browser)

import json
from xxx.models import alert
from django.core import serializers

def test(request):
    alert_list = alert.objects.all()

    tmpJson = serializers.serialize("json",alert_list)
    tmpObj = json.loads(tmpJson)

    return HttpResponse(json.dumps(tmpObj))

Woollyheaded

Will be better just HttpResponse(tmpObj) – Graniela

Answer 7

First I added a to_dict method to my model ;

def to_dict(self):
    return {"name": self.woo, "title": self.foo}

Then I have this;

class DjangoJSONEncoder(JSONEncoder):

    def default(self, obj):
        if isinstance(obj, models.Model):
            return obj.to_dict()
        return JSONEncoder.default(self, obj)


dumps = curry(dumps, cls=DjangoJSONEncoder)

and at last use this class to serialize my queryset.

def render_to_response(self, context, **response_kwargs):
    return HttpResponse(dumps(self.get_queryset()))

This works quite well

Subtype

Answer 8

For Django Model, try:

users = User.objects.all()   
return JsonResponse ({'data' : list(users)}) 

Extremity

Answer 9

You can use this for the Django model. Here we get rid of the wrapper because of safe=False, without it there will be an error. But .values() will return you the key->value in a multidimensional array

views.py

from django.http import JsonResponse

users = User.objects.all().values()
return JsonResponse(list(users), safe=False)

Bihar

Remember that Stack Overflow isn't just intended to solve the immediate problem, but also to help future readers find solutions to similar problems, which requires understanding the underlying code. This is especially important for members of our community who are beginners, and not familiar with the syntax. Given that, can you edit your answer to include an explanation of what you're doing and why you believe it is the best approach? – Rackety