ValueError: Cannot serialize: <bound method SiteManager.get_current of <django.contrib.sites.models.SiteManager object at 0xb647c9ac>>

[jedie]

Traceback (most recent call last):
  File "./manage.py", line 13, in <module>
    execute_from_command_line(sys.argv)
  File "/home/jens/PyLucid_env/lib/python3.4/site-packages/django/core/management/__init__.py", line 385, in execute_from_command_line
    utility.execute()
  File "/home/jens/PyLucid_env/lib/python3.4/site-packages/django/core/management/__init__.py", line 377, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/jens/PyLucid_env/lib/python3.4/site-packages/django/core/management/base.py", line 288, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/home/jens/PyLucid_env/lib/python3.4/site-packages/django/core/management/base.py", line 338, in execute
    output = self.handle(*args, **options)
  File "/home/jens/PyLucid_env/lib/python3.4/site-packages/django/core/management/commands/makemigrations.py", line 124, in handle
    self.write_migration_files(changes)
  File "/home/jens/PyLucid_env/lib/python3.4/site-packages/django/core/management/commands/makemigrations.py", line 152, in write_migration_files
    migration_string = writer.as_string()
  File "/home/jens/PyLucid_env/lib/python3.4/site-packages/django/db/migrations/writer.py", line 131, in as_string
    operation_string, operation_imports = OperationWriter(operation).serialize()
  File "/home/jens/PyLucid_env/lib/python3.4/site-packages/django/db/migrations/writer.py", line 82, in serialize
    arg_string, arg_imports = MigrationWriter.serialize(item)
  File "/home/jens/PyLucid_env/lib/python3.4/site-packages/django/db/migrations/writer.py", line 263, in serialize
    item_string, item_imports = cls.serialize(item)
  File "/home/jens/PyLucid_env/lib/python3.4/site-packages/django/db/migrations/writer.py", line 333, in serialize
    return cls.serialize_deconstructed(path, args, kwargs)
  File "/home/jens/PyLucid_env/lib/python3.4/site-packages/django/db/migrations/writer.py", line 239, in serialize_deconstructed
    arg_string, arg_imports = cls.serialize(arg)
  File "/home/jens/PyLucid_env/lib/python3.4/site-packages/django/db/migrations/writer.py", line 409, in serialize
    "topics/migrations/#migration-serializing" % value
ValueError: Cannot serialize: <bound method SiteManager.get_current of <django.contrib.sites.models.SiteManager object at 0xb647c9ac>>
There are some values Django cannot serialize into migration files.
For more, see https://docs.djangoproject.com/en/dev/topics/migrations/#migration-serializing

one up with Pdb:

(Pdb) l
328  	        elif isinstance(value, decimal.Decimal):
329  	            return repr(value), set(["from decimal import Decimal"])
330  	        # Django fields
331  	        elif isinstance(value, models.Field):
332  	            attr_name, path, args, kwargs = value.deconstruct()
333  ->	            return cls.serialize_deconstructed(path, args, kwargs)
334  	        # Classes
335  	        elif isinstance(value, type):
336  	            special_cases = [
337  	                (models.Model, "models.Model", []),
338  	            ]
(Pdb) a
cls = <class 'django.db.migrations.writer.MigrationWriter'>
value = <django.db.models.fields.related.ForeignKey: site>
{{{

one Up again:
{{{
(Pdb) l
234  	        for arg in args:
235  	            arg_string, arg_imports = cls.serialize(arg)
236  	            strings.append(arg_string)
237  	            imports.update(arg_imports)
238  	        for kw, arg in kwargs.items():
239  ->	            arg_string, arg_imports = cls.serialize(arg)
240  	            imports.update(arg_imports)
241  	            strings.append("%s=%s" % (kw, arg_string))
242  	        return "%s(%s)" % (name, ", ".join(strings)), imports
243  	
244  	    @classmethod
(Pdb) a
cls = <class 'django.db.migrations.writer.MigrationWriter'>
path = 'django.db.models.ForeignKey'
args = []
kwargs = {'default': <bound method SiteManager.get_current of <django.contrib.sites.models.SiteManager object at 0xb647c9ac>>, 'to': 'sites.Site'}
}}}


}}}

[jedie]

Ah, seems that this is the trigger for this:

    site = models.ForeignKey(Site,
        default=Site.objects.get_current
    )

I change this to:

    site = models.ForeignKey(Site,
        default=settings.SITE_ID,
    )

[Simon Charette]

As pointed out in the stacktrace you should refer to the ​documentation.

Due to the fact __qualname__ was only introduced in Python 3, Django can only serialize the following pattern (an unbound method used within the class body) on Python 3, and will fail to serialize a reference to it on Python 2:
If you are using Python 2, we recommend you move your methods for upload_to and similar arguments that accept callables (e.g. default) to live in the main module body, rather than the class body.