# MySQL Connector/Python - MySQL driver written in Python.
import django
if django.VERSION >= (1, 8):
from django.db.backends.base.validation import BaseDatabaseValidation
else:
from django.db.backends import BaseDatabaseValidation
if django.VERSION < (1, 7):
from django.db import models
else:
from django.core import checks
from django.db import connection
class DatabaseValidation(BaseDatabaseValidation):
if django.VERSION < (1, 7):
def validate_field(self, errors, opts, f):
"""
MySQL has the following field length restriction:
No character (varchar) fields can have a length exceeding 255
characters if they have a unique index on them.
"""
varchar_fields = (models.CharField,
models.CommaSeparatedIntegerField,
models.SlugField)
if isinstance(f, varchar_fields) and f.max_length > 255 and f.unique:
msg = ('"%(name)s": %(cls)s cannot have a "max_length" greater '
'than 255 when using "unique=True".')
errors.add(opts, msg % {'name': f.name,
'cls': f.__class__.__name__})
else:
def check_field(self, field, **kwargs):
"""
MySQL has the following field length restriction:
No character (varchar) fields can have a length exceeding 255
characters if they have a unique index on them.
"""
# Django 1.7
errors = super(DatabaseValidation, self).check_field(field,
**kwargs)
# Ignore any related fields.
if getattr(field, 'rel', None) is None:
field_type = field.db_type(connection)
if field_type is None:
return errors
if (field_type.startswith('varchar') # Look for CharFields...
and field.unique # ... that are unique
and (field.max_length is None or
int(field.max_length) > 255)):
errors.append(
checks.Error(
('MySQL does not allow unique CharFields to have a '
'max_length > 255.'),
hint=None,
obj=field,
id='mysql.E001',
)
)
return errors
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