55 lines
1.8 KiB
Python
55 lines
1.8 KiB
Python
from sqlalchemy.ext.instrumentation import InstrumentationManager
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# from sqlalchemy.orm.interfaces import AttributeExtension
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from sqlalchemy.orm import ColumnProperty
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from sqlalchemy.types import String
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from sqlalchemy import event
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class Error(Exception):
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"""Base class for exceptions in this module."""
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pass
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class ValidationError(Error):
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pass
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class JeevesDBError(Error):
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"""Exception raised for errors in the input.
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Attributes:
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expression -- input expression in which the error occurred
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message -- explanation of the error
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"""
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def __init__(self, field, message):
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super().__init__(message)
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self.field = field
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self.message = message
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class InstallValidatorListeners(InstrumentationManager):
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def post_configure_attribute(self, class_, key, inst):
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"""Add validators for any attributes that can be validated."""
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prop = inst.prop
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# Only interested in simple columns, not relations
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if isinstance(prop, ColumnProperty) and len(prop.columns) == 1:
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col = prop.columns[0]
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# if we have string column with a length, create a length validator listner
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if isinstance(col.type, String) and col.type.length:
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event.listen(
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getattr(class_, key), 'set', LengthValidator(
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col.name, col.type.length), retval=True)
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class LengthValidator():
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def __init__(self, col_name, max_length):
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self.col_name = col_name
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self.max_length = max_length
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def __call__(self, state, value, oldvalue, initiator):
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if len(value) > self.max_length:
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raise ValidationError(
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"%s.%s: Length %d exceeds allowed %d" % (
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state.__class__.__name__, self.col_name, len(value), self.max_length))
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return value
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