The Python "TypeError: Object of type function is not JSON serializable" occurs when we try to serialize a function to JSON. To solve the error, make sure to call the function and serialize the object that the function returns.
JSON is a text based data interchange format. Any Python object can be serialized into JSON format and vice versa. All popular programming languages support converting objects into JSON and vice versa.
To serialize a queryset or list of objects instead of a single object instance, you should pass the many=True flag when instantiating the serializer. You can then pass a queryset or list of objects to be serialized.
Django JsonResponse If the safe parameter is set to False , any object can be passed for serialization; otherwise only dict instances are allowed.
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")
Hope that helps.
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)})
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) )
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))
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
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