#28329: Wrong type conversion with MySQL 5.7
-------------------------------------+-------------------------------------
Reporter: | Owner: nobody
dapicester |
Type: Bug | Status: new
Component: Database | Version: 1.10
layer (models, ORM) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
Hi,
I found that the wrong SQL is generated for MySQL 5.7 when using
`django.db.models.functions.Cast`.
Suppose I have a model:
{{{
class Model(models.Model):
id = models.AutoField()
string = models.CharField()
}}}
This works correctly, cast a string to integer:
{{{
print Model.objects.annotate(as_int=functions.Cast('string',
models.IntegerField())).query
SELECT `Model`.`id`, `Model`.`string`, CAST(`Model`.`string`) AS signed
integer) AS `as_int` FROM `Model`
}}}
But if cast to unsigned integer (which is what I need):
{{{
print Model.objects.annotate(as_int=functions.Cast('string',
models.PositiveIntegerField())).query
SELECT `Model`.`id`, `Model`.`string`, CAST(`Model`.`string`) AS integer
UNSIGNED) AS `as_int` FROM `Model`
}}}
Here is the error:
{{{
Model.objects.annotate(as_int=functions.Cast('string',
models.PositiveIntegerField()))
ProgrammingError: (1064, "You have an error in your SQL syntax; check the
manual that corresponds to your MySQL server version for the right syntax
to use near 'integer UNSIGNED) AS `id_int` FROM `Model` at line 1")
}}}
So it seems that casting to `IntegerField` uses the correct MySQL type
`signed integer` but casting to `PositiveInteger` uses the wrong type
`integer unsigned` (it should be `unsigned integer`, see the MySQL
documentation at https://dev.mysql.com/doc/refman/5.7/en/cast-
functions.html#function_cast).
--
Ticket URL: <https://code.djangoproject.com/ticket/28329>
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