Is there a way to create an Enum class that will be created automatically when creating a new database, for example, the standard Enum, but also connect it to the TypeDecorator , which starts process_bind_param ?
This first block of code creates an Enum type that automatically reduces data entry before saving, but, unlike a regular Enum , a specific PostgreSQL enumeration type is automatically created in the database, so run create_all() throws an error when creating the table, because language_code does not exist in the PostgreSQL schema.
class LowercaseEnum(sqlalchemy.types.TypeDecorator): '''Converts input to lowercase.''' impl = sqlalchemy.types.Enum def process_bind_param(self, value, dialect): return value.lower() class Foo(Model): id = sqlalchemy.Column(sqlalchemy.Integer, primary_key=True) language_code = sqlalchemy.Column(LowercaseEnum(*['de', 'en'], name='language_code'))
If, on the other hand, I define my custom type, as in this second block of code, then it is automatically created when create_all() called, but the process_bind_param method is never called when sending values to the database, so the lower case does not work.
class LowercaseEnum(sqlalchemy.dialects.postgresql.ENUM, sqlalchemy.types.TypeDecorator): '''Converts input to lowercase.''' impl = sqlalchemy.types.Enum def process_bind_param(self, value, dialect): return value.lower()
I also tried several different inheritance combinations from TypeDecorator in a separate class that was mixed, and also switched to sqlalchemy.types.Enum and sqlalchemy.dialects.postgresql.ENUM , but it seems that no matter what I do, I either get a class that is created automatically, or a class that starts process_bind_param , but never both.