python - UUID('...') is not JSON serializable

Question

I get this error when i try to pass the UUID attribute to url parameter.

urlpatterns = [
    url(r'^historia-clinica/(?P<uuid>[W\d\-]+)/$', ClinicHistoryDetail.as_view(), name='...'),
]

views.py

class ClinicHistoryDetail(...):
     ...
     my_object = MyModel.objects.create(...)
     ...
     return redirect(reverse('namespace:name', kwargs={'uuid' : my_object.id}))

model.py

class MyModel(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    ...

Any suggestions?

Answer 1

There is a bug ticket on Django regarding this issue however a custom so called 'complex encoder' by python docs can help you.

import json
from uuid import UUID


class UUIDEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, UUID):
            # if the obj is uuid, we simply return the value of uuid
            return obj.hex
        return json.JSONEncoder.default(self, obj)

Now if we did something like this

json.dumps(my_object, cls=UUIDEncoder)

Your uuid field should be encoded.

Answer 2

For using the UUID in a URL like that, you should pass it as a string:

 return redirect(reverse('namespace:name', kwargs={'uuid' : str(object.id)}))

FYI - it looks like WIMs answer is a bit more thorough. Your regex should certainly be tightened up. If you end up using the string representation of the slug, you'll want a regex like this: [A-Za-z0-9\-]+ which allows for alphanumerics and hyphens.

Answer 3

Convert UUID to str.

uuid_str = str(uuid_item)

Answer 4

I use convert function for this, it is simple and clean.

import json
from uuid import UUID
def uuid_convert(o):
        if isinstance(o, UUID):
            return o.hex

json.dumps(users,indent=4,default=uuid_convert)

Answer 5

I had this same problem with a UUID field in a database model that I wanted to print out for debugging. I found that the pprint() function from the pprint module can handle this. You can also give it an indent argument to get the same kind of indented output that you would get from json.dumps()

https://docs.python.org/3/library/pprint.html#pprint.pprint

Example:

>>> import uuid
>>> import pprint
>>> import json
>>> x = uuid.UUID('12345678123456781234567812345678')
>>> x
UUID('12345678-1234-5678-1234-567812345678')
>>> print(x)
12345678-1234-5678-1234-567812345678
>>> json.dumps(x)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
...
...
    raise TypeError(repr(o) + " is not JSON serializable")
TypeError: UUID('12345678-1234-5678-1234-567812345678') is not JSON serializable
>>> pprint.pprint(x)
UUID('12345678-1234-5678-1234-567812345678')