id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
21290	"Add migration docs for (or avoid) ""Cannot serialize"" errors"	Tim Graham	Andrew Godwin	"The migration writer raises a `ValueError: Cannot serialize: <foo>` for models that have defaults like:

1. `models.DateField(default=datetime.today)`
2. `models.DecimalField(default=Decimal('1.000')`

Suggested workarounds by loic84 in IRC:

1. `datetime.date.today` is whitelisted, `datetime.datetime.today` isn't.
2. `def default_decimal(): return Decimal('1.000')` then `default=default_decimal.`

This is confusing for users coming from south where things just worked. We should either add docs about this problem or figure out a way to avoid these errors."	Cleanup/optimization	closed	Migrations	dev	Release blocker	fixed		loic@…	Accepted	0	0	0	0	0	0