`simpleml.persistables.sqlalchemy_types`¶

Platform independent sqlalchemy types

Module Contents¶

Classes¶

`GUID`	Platform-independent GUID type.
`JSON`	Platform-independent JSON type

simpleml.persistables.sqlalchemy_types.MutableJSON[source]¶

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 the impl is a callable, and the resulting object is assigned to the self.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.

impl[source]¶

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 of type_engine() to help determine what type should ultimately be returned for a given TypeDecorator.

By default returns self.impl.

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 DBAPI execute() 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.

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 method fetchone() or similar.