South migrate error: name 'UUID' is not defined

django django-south
daveoncode picture daveoncode · Feb 23, 2013 · Viewed 10.1k times · Source

I have a model with a CharField field with a default value of uuid4:

f = models.CharField(default=uuid4, max_length=36, unique=True, blank=True)

and this is causing the following error:

Cannot successfully create field 'f' for model 'm': name 'UUID' is not defined.

running the migrate commmand! Ho can I fix this issue? so far I tried:

  • to define a "wrapper function" in the module for uuid (ie: def getUUID())
  • to set the default value of "f" by overriding the Model constructor

...but the problem remains :(

ps. I know that I can instruct south for custom fields, but I'm not using custom fields in my opinion :P

Answer

daveoncode picture daveoncode · Feb 23, 2013

I solved defining the following helper function in my model's module:

from uuid import uuid4

def generateUUID():
    return str(uuid4())

then:

f = models.CharField(default=generateUUID, max_length=36, unique=True, editable=False)

south will generate a migration file (migrations.0001_initial) with a generated UUID like:

default='5c88ff72-def3-4842-8d48-a75bb3240bb5'

this is pretty unhappy... since that string is "static", instead it must be created dynamically using the helper function... anyway in the django's world al seems working as expected... I added some records into the database and a new UUID was generated for each one. I then tried my first schema migration by adding a couple of fields to my model and they has been added to the database table as expected.

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