Do not rely on notifiction module being imported
This has worked so far mostly by accident, but it turned out to be
brittle while writing tests. This makes sure that the notification
module is always imported before use.
from django.db.backends import BaseDatabaseValidation
class DatabaseValidation(BaseDatabaseValidation):
def validate_field(self, errors, opts, f):
"Prior to MySQL 5.0.3, character fields could not exceed 255 characters"
from django.db import models
from django.db import connection
db_version = connection.get_server_version()
if db_version < (5, 0, 3) and isinstance(f, (models.CharField, models.CommaSeparatedIntegerField, models.SlugField)) and f.max_length > 255:
errors.add(opts,
'"%s": %s cannot have a "max_length" greater than 255 when you are using a version of MySQL prior to 5.0.3 (you are using %s).' %
(f.name, f.__class__.__name__, '.'.join([str(n) for n in db_version[:3]])))