<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'Gxe9nxe9ral', u'en': u'General'}, u'value': {u'fr': [u'bar', u'rxe9ception 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?
Answers:
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")
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
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
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) )
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)})
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))
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)
For Django Model, try:
users = User.objects.all()
return JsonResponse ({'data' : list(users)})
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)
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'Gxe9nxe9ral', u'en': u'General'}, u'value': {u'fr': [u'bar', u'rxe9ception 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?
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")
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
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
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) )
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)})
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))
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)
For Django Model, try:
users = User.objects.all()
return JsonResponse ({'data' : list(users)})
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)