75 lines
2.1 KiB
Python
75 lines
2.1 KiB
Python
import sqlalchemy as sa
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def coercion_listener(mapper, class_):
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"""
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Auto assigns coercing listener for all class properties which are of coerce
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capable type.
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"""
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for prop in mapper.iterate_properties:
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try:
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listener = prop.columns[0].type.coercion_listener
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except AttributeError:
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continue
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sa.event.listen(
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getattr(class_, prop.key),
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'set',
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listener,
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retval=True
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)
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def instant_defaults_listener(target, args, kwargs):
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for key, column in sa.inspect(target.__class__).columns.items():
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if column.default is not None:
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if callable(column.default.arg):
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setattr(target, key, column.default.arg(target))
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else:
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setattr(target, key, column.default.arg)
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def force_auto_coercion(mapper=sa.orm.mapper):
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"""
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Function that assigns automatic data type coercion for all classes which
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are of type of given mapper. The coercion is applied to all coercion
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capable properties. By default coercion is applied to all SQLAlchemy
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mappers.
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Before initializing your models you need to call force_auto_coercion.
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::
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from sqlalchemy_utils import force_auto_coercion
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force_auto_coercion()
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Then define your models the usual way::
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class Document(Base):
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__tablename__ = 'document'
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id = sa.Column(sa.Integer, autoincrement=True)
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name = sa.Column(sa.Unicode(50))
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background_color = sa.Column(ColorType)
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Now scalar values for coercion capable data types will convert to
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appropriate value objects::
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document = Document()
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document.background_color = 'F5F5F5'
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document.background_color # Color object
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session.commit()
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:param mapper: The mapper which the automatic data type coercion should be
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applied to
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"""
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sa.event.listen(mapper, 'mapper_configured', coercion_listener)
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def force_instant_defaults(mapper=sa.orm.mapper):
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sa.event.listen(mapper, 'init', instant_defaults_listener)
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