mypy compliance when using custom column classes

[andylamp]

Hello,

Thanks for the awesome library! I would like to ask how can we allow custom classes derived from Column to pass mypy type checking. More concretely, let us suppose we have the following (simple?) class:

class TransformedString(rom.Column):
    """
    Transformation on strings
    """

    _allowed = bytes

    def _to_redis(self, value):
        return value

    def _from_redis(self, value):
        return value

and suppose that we have the following ORM model:

class MyModel(rom.Model):
    """Entry representing MyModel"""

    id = rom.PrimaryKey(index=True)
    number = rom.Integer()
    html = TransformedString()

Now if I go and assign values as follows, while it works mypy throws an error.

# assume an instance of `MyModel`
my_model.number = 1 # works!
my_model.html = str.encode("a_nice_long_string_with_many_features") # mypy throws an error

The error mypy throws is the following:

error: Incompatible types in assignment (expression has type "bytes", variable has type "TransformedString")

How am I able to fix this without resorting to ignoring the types altogether?

[josiahcarlson]

I haven't done any work to make Rom specifically mypy compliant in any way. I'll have to look at how other libraries do this, and how mypy recommends solving this when I get back to a computer in January.

…

On Sun, Feb 13, 2022, 9:34 AM andylamp ***@***.***> wrote: Hello, Thanks for the awesome library! I would like to ask how can we allow custom classes derived from Column to pass mypy type checking? for example, let us suppose we have the following (simple?) class: class TransformedString(rom.Column): """ Transformation on strings """ _allowed = bytes def _to_redis(self, value): return value def _from_redis(self, value): return value and suppose that we have the following ORM model: class MyModel(rom.Model): """Entry representing a GitHub issue""" id = rom.PrimaryKey(index=True) number = rom.Integer() html = TransformedString() Now if I go and assign values as follows, while it works mypy throws an error. # assume an instance of `MyModel`my_model.number = 1 # works!my_model.html = str.encode("a_nice_long_string_with_many_features") # mypy throws an error The error mypy throws is the following: error: Incompatible types in assignment (expression has type "bytes", variable has type "TransformedString") How am I able to fix this without resorting to ignoring the types altogether? — Reply to this email directly, view it on GitHub <#155>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABTDQQMA3PZFWKYPQUPHK3U27FRPANCNFSM5OJF33GA> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>