simpleml.persistables.sqlalchemy_types
¶
Platform independent sqlalchemy types
Module Contents¶
Classes¶
Platform-independent GUID type. |
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Platform-independent JSON type |
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class
simpleml.persistables.sqlalchemy_types.
GUID
(*args, **kwargs)[source]¶ Bases:
sqlalchemy.types.TypeDecorator
Platform-independent GUID type.
Uses PostgreSQL’s UUID type, otherwise uses CHAR(32), storing as stringified hex values.
http://docs.sqlalchemy.org/en/latest/core/custom_types.html
Construct a
TypeDecorator
.Arguments sent here are passed to the constructor of the class assigned to the
impl
class level attribute, assuming theimpl
is a callable, and the resulting object is assigned to theself.impl
instance attribute (thus overriding the class attribute of the same name).If the class level
impl
is not a callable (the unusual case), it will be assigned to the same instance attribute ‘as-is’, ignoring those arguments passed to the constructor.Subclasses can override this to customize the generation of
self.impl
entirely.-
load_dialect_impl
(self, dialect)[source]¶ Return a
TypeEngine
object corresponding to a dialect.This is an end-user override hook that can be used to provide differing types depending on the given dialect. It is used by the
TypeDecorator
implementation oftype_engine()
to help determine what type should ultimately be returned for a givenTypeDecorator
.By default returns
self.impl
.
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process_bind_param
(self, value, dialect)[source]¶ Receive a bound parameter value to be converted.
Subclasses override this method to return the value that should be passed along to the underlying
TypeEngine
object, and from there to the DBAPIexecute()
method.The operation could be anything desired to perform custom behavior, such as transforming or serializing data. This could also be used as a hook for validating logic.
This operation should be designed with the reverse operation in mind, which would be the process_result_value method of this class.
- Parameters
value – Data to operate upon, of any type expected by this method in the subclass. Can be
None
.dialect – the
Dialect
in use.
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process_result_value
(self, value, dialect)[source]¶ Receive a result-row column value to be converted.
Subclasses should implement this method to operate on data fetched from the database.
Subclasses override this method to return the value that should be passed back to the application, given a value that is already processed by the underlying
TypeEngine
object, originally from the DBAPI cursor methodfetchone()
or similar.The operation could be anything desired to perform custom behavior, such as transforming or serializing data. This could also be used as a hook for validating logic.
- Parameters
value – Data to operate upon, of any type expected by this method in the subclass. Can be
None
.dialect – the
Dialect
in use.
This operation should be designed to be reversible by the “process_bind_param” method of this class.
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class
simpleml.persistables.sqlalchemy_types.
JSON
(*args, **kwargs)[source]¶ Bases:
sqlalchemy.types.TypeDecorator
Platform-independent JSON type
Uses PostgreSQL’s JSONB type, otherwise falls back to standard JSON
Construct a
TypeDecorator
.Arguments sent here are passed to the constructor of the class assigned to the
impl
class level attribute, assuming theimpl
is a callable, and the resulting object is assigned to theself.impl
instance attribute (thus overriding the class attribute of the same name).If the class level
impl
is not a callable (the unusual case), it will be assigned to the same instance attribute ‘as-is’, ignoring those arguments passed to the constructor.Subclasses can override this to customize the generation of
self.impl
entirely.-
load_dialect_impl
(self, dialect)[source]¶ Return a
TypeEngine
object corresponding to a dialect.This is an end-user override hook that can be used to provide differing types depending on the given dialect. It is used by the
TypeDecorator
implementation oftype_engine()
to help determine what type should ultimately be returned for a givenTypeDecorator
.By default returns
self.impl
.
-