Support for Custom Column Types?

[mekhami]

I don't see anything in the documentation and a brief look through the source code didn't reveal anything immediately. I have a custom GUID type (as documented in the sqlalchemy docs here: http://docs.sqlalchemy.org/en/latest/core/custom_types.html#backend-agnostic-guid-type) and when I try to use the SQLAlchemyObjectType with the model metaclass, it doesn't know how to convert type GUID. Is there a way to handle these custom column types? Do I need to just subclass SQLAlchemyObjectType and make it understand what that is?

Thanks for any help.

[mekhami]

Ah, I can register them the same way the converters are registered in converter.py

Sorry for the bother!

[rodneykeeling]

Can you explain how you did this? Did you just modify the source, or was there a better way of adding another type?

[jcouser]

I just ran into this same issue as well. We have several custom subclasses of TypeDecorator from sqlalchemy.types

Currently the solution is to modify graphene_sqlalchemy/converter.py

Importing out custom types decorating the convert_column_to_string method like so:
@convert_sqlalchemy_type.register(GUID)

I'd love to know of a better solution without modifying graphene_sqlalchemy.

[mekhami]

You don't have to use the convert_sqlalhemy_type.register function in graphene_sqlalchemy/converter.py. You can use it anywhere! So wherever you declare your schema, you can do this:

from my_custom_types import GUID

@convert_sqlalchemy_type.register(GUID)
def convert_column_to_string(type, column, registry=None):
    return String(description=get_column_doc(column),
                  required=not(is_column_nullable(column)))

Whenever your schema is imported and run, the conversion will also be registered.

[jcouser]

Awesome thanks for the tip. This allowed me to move the decorators and leave the module unmodified. Thanks!

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