35 lines
1.3 KiB
Python
35 lines
1.3 KiB
Python
from django.core import checks
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from django.db.backends import BaseDatabaseValidation
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class DatabaseValidation(BaseDatabaseValidation):
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def check_field(self, field, **kwargs):
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"""
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MySQL has the following field length restriction:
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No character (varchar) fields can have a length exceeding 255
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characters if they have a unique index on them.
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"""
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from django.db import connection
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errors = super(DatabaseValidation, self).check_field(field, **kwargs)
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try:
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field_type = field.db_type(connection)
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except AttributeError:
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# If the field is a relative field and the target model is
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# missing, then field.rel.to is not a model and doesn't have
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# `_meta` attribute.
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field_type = ''
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if (field_type.startswith('varchar') and field.unique
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and (field.max_length is None or int(field.max_length) > 255)):
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errors.append(
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checks.Error(
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('Under mysql backend, the field cannot have a "max_length" '
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'greated than 255 when it is unique.'),
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hint=None,
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obj=field,
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id='E047',
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)
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)
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return errors
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