Opened 6 years ago
Last modified 6 years ago
#29881 closed Bug
Decimal data type mapping triggers bug in MySQL — at Initial Version
| Reported by: | Par Andersson | Owned by: | nobody |
|---|---|---|---|
| Component: | Database layer (models, ORM) | Version: | 2.1 |
| Severity: | Normal | Keywords: | mysql, decimal, numeric |
| Cc: | Triage Stage: | Unreviewed | |
| Has patch: | yes | Needs documentation: | no |
| Needs tests: | no | Patch needs improvement: | no |
| Easy pickings: | yes | UI/UX: | no |
Description
Casting to DecimalField triggers a bug in MySQL due to DecimalField being mapped to numeric.
Example:
Model.objects.annotate(bug=Cast('somefield', DecimalField(10,2)))
Will generate an error from MySQL, the issue is that MySQL has an issue where it's not possible to cast to numeric as reported here:
https://bugs.mysql.com/bug.php?id=84558
With Django this happens due to the data type mapping defined in data_types (db/backends/mysql/base.py:111 to be exact):
'DecimalField': 'numeric(%(max_digits)s, %(decimal_places)s)',
I propose that this line is changed to:
'DecimalField': 'decimal(%(max_digits)s, %(decimal_places)s)',
as this seems to be a simple work around for the underlying issue.
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