a bug in model.Manager.values_list?

[Ws Hu]

import json
from myapp.models import MyModel


x = json.dumps(MyModel.objects.values_list('myField', flat=True)) # "[] is not JSON serializable"
x = json.dumps([x for x in MyModel.objects.values_list('myField', flat=True)]) #ok

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It seems that the database is accessed only if the result of objects.filter()/all()/values_list()/... is printed/iterated/... .

It's fine, but I think the methods of model manager like filter()/all()/values_list() should behave as if it is processing python objects. I have not yet digged into json module, but it did penetrated django's disguise.

[Derek]

"Its not a bug, its a feature."

See: https://docs.djangoproject.com/en/1.9/ref/models/querysets/#when-querysets-are-evaluated

If you were designing Django's internals, you might have decided that the Queryset "should behave" in a certain way, but the designers have chosen this approach.  There is no "disguise" about this; it's well-known and well-documented.

[knbk]

Models and querysets are not serializeable using the default `json` tools, but Django provides its own set of tools that allow you to serialize models and querysets. Take a look at serializing django objects.