#26139: UUIDField value must be declared "binary" to avoid MySQL warning
-------------------------------------+-------------------------------------
Reporter: Guilhem Bichot | Owner: nobody
Type: Bug | Status: closed
Component: Database layer | Version: 1.9
(models, ORM) |
Severity: Normal | Resolution: invalid
Keywords: MySQL | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by Chris Foresman):
Replying to [comment:3 Tim Graham]:
> Yes, Claude is correct. Django's `UUIDField` uses `char(32)` -- the
`binary(16)` representation is a third-party implementation. The warnings
I'm seeing for Django's test suite are for `BinaryField` (created #26140).
I've been researching this; is there a reason we _don't_ use `BINARY(16)`
for MySQL? It should be massively [http://mysqlserverteam.com/storing-
uuid-values-in-mysql-tables/ more efficient] in storage and index space. I
think if I subclass the existing `UUIDField`, this should be pretty close
to working (I think I need to override `__init__` to set the `max_length`
to 16:
{{{
class MySQLUUIDField(UUIDField):
def get_internal_type(self):
return "BinaryField"
def get_db_prep_value(self, value, connection, prepared=False):
if value is None:
return None
if not isinstance(value, uuid.UUID):
value = self.to_python(value)
if connection.features.has_native_uuid_field:
return value
return value.bytes
def to_python(self, value):
if value is not None and not isinstance(value, uuid.UUID):
try:
return uuid.UUID(bytes=value)
except (AttributeError, ValueError):
raise exceptions.ValidationError(
self.error_messages['invalid'],
code='invalid',
params={'value': value},
)
return value
}}}
I'm taking some liberties and not accounting for every edge case, but I
think that's enough to work with the existing MySQL backend as written,
though ideally I'd like the backend to presume `BINARY(16)` and the field
definition could act accordingly. Looking at Oracle and sqlite, those DBs
use a `BLOB` type for binary data, so I'm not sure if there is any benefit
or not using that type for a UUID.
--
Ticket URL: <https://code.djangoproject.com/ticket/26139#comment:4>
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