Subclasses can override this to customize the generation Ignoring those arguments passed to the constructor. It will be assigned to the same instance attribute ‘as-is’, If the class level impl is not a callable (the unusual case), (thus overriding the class attribute of the same name). Object is assigned to the self.impl instance attribute Of the class assigned to the impl class level attribute,Īssuming the impl is a callable, and the resulting _init_ ( * args : Any, ** kwargs : Any ) ¶Īrguments sent here are passed to the constructor reverse_operate ( op : OperatorType, other : Any, ** kwargs : Any ) → ColumnElement ¶ *other ¶ – the ‘other’ side of the operation. Python objects into bind parameters within expressions. This is used to give the expression system a hint when coercing Used may want to define the erce_compared_value() Types that receive a Python type that isn’t similar to the ultimate type See TypeDecorator.cache_ok for further notes on how this works. To produce the same bind/result behavior and SQL generationĮvery time, this flag should be set to False otherwise if theĬlass produces the same behavior each time, it may be set to True. When the SQL compiler attempts to generate a cache key for a statement This flag defaults to None which will initially generate a warning The TypeDecorator.cache_ok class-level flag indicates if thisĬustom TypeDecorator is safe to be used as part of a cache key. Given in this case, the impl variable can reference Method can be used to provide different type classes based on the dialect The class-level impl attribute is required, and can reference any This method is preferred to direct subclassing of SQLAlchemy’sīuilt-in types as it ensures that all required functionality of Object NameĪllows the creation of types which add additional functionality Needs to be normalized in some way that is specific to the business caseĪnd isn’t as generic as a datatype. This technique may be more appropriate when data coming into an ORM model When using the ORM, a similar technique exists for converting user dataįrom arbitrary formats which is to use the validates() decorator. The TypeDecorator can be used to provide a consistent means ofĬonverting some type of value as it is passed into and out of the database.
Practice and SQLAlchemy no longer supports this as a public use case. Handling for a given type through direct subclassing, it is never needed in Type, which is customized by SQLAlchemy on a per-DBAPI basis to perform Is in addition to the processing already performed by the hosted The bind- and result-processing of TypeDecorator Working with Custom Types and Reflection.Applying SQL-level Bind/Result Processing.Linking Python uuid.UUID to the Custom Type for ORM mappings.Store Timezone Aware Timestamps as Timezone Naive UTC.
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