Fixed #17854 -- Added database-specific validation for DecimalField max_digits and decimal_places limits. #19654
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| errors.append( | ||
| checks.Warning( | ||
| "%s does not support DecimalField with max_digits > 38." | ||
| % self.connection.display_name, | ||
| obj=field, | ||
| id="oracle.W001", | ||
| ) | ||
| ) | ||
|
|
||
| if field.decimal_places > 127: |
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Any reason not to create, per database backend, constants variables at module or class scopes for the values used to verify the max_digits and decimal_places, and then reuse them in validation and messages?
Okay, maybe the only benefit of this is the reduction in duplication of hardcoded numbers in the codebase and messages and the reduction in the number of places that need to be changed if a new database version changes it limits.
Another question is whether the constant variables should be in the public API or in the private API of the database backend.
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Yup absolutely these magic numbers would need to be removed 👍
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I agree, we should set something like max_digits = None and max_decimal_places = None to django.db.backends.base.features.BaseDatabaseFeatures and update these for the specific backends
This also means if the backend changes the limit, we can calculate it based off the database version (as we do with other flags here)
I also think the validation should be within django.db.models.fields.DecimalField._check_decimal_places and django.db.models.fields.DecimalField._check_max_digits. You can look at the GeneratedField checks for inspiration on getting database specific validation
Also think that the error id's should be within fields and documented once.
Trac ticket number
Ticket-17854
Branch description
Add database-specific DecimalField validation for precision limits
Add warnings when DecimalField max_digits/decimal_places exceed database limits:
Includes tests and documentation updates.
Checklist
mainbranch.