Python type hinting on imported modules









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I find that the autocomplete for Flask is somewhat lacking--this is because internally, context-specific objects such as current_app, request, and logger are actually LocalProxys. Thus PyCharm reasonably has no idea what to do with this type.



So the obvious solution to this, to me would be to apply type hints on the imported modules. Except you can't do that! As of Python 3.7 there appears to be no such syntax to facilitate this.



So the next-obvious solution would be to make local copies of each context-specific module with the type explicitly set like so:



from logging import Logger
from flask import Flask, Request, Blueprint, request, current_app as app

app: Flask = app
logger: Logger = app.logger
request: Request = request


...which works until you actually attempt to start the server, in which case the application crashes because of a RuntimeError: Working outside of application context.



It turns out that we can actually encapsulate the relevant type hints inside of a class or other scope inside of the application context.



@foo_blueprint.route('/foo', methods=['GET'])
def foo(cls):
_app: Flask = app
_logger: Logger = app.logger
_request: Request = request
# ...


...which works but is incredibly awkward in every imaginable sense.



Is there a reasonable solution for getting proper type hints inside of an application context in Flask?










share|improve this question





















  • maybe it will be useful
    – Danila Ganchar
    Nov 9 at 8:42










  • Flask is only supported in the professional edition of Pycharm jetbrains.com/help/pycharm/flask.html Which version of Pycharm are you using: Community Edition or Professional?
    – Eskapp
    Nov 9 at 16:01










  • I use the Community Edition (was not aware of dedicated support of particular libraries), but this question was written in general for those awful libraries that smash together types at runtime (such as Boto3).
    – I'll Eat My Hat
    Nov 10 at 18:13










  • cont'd: Flask as an example was merely the latest, most widely used, and has what is probably the simplest problems and workarounds.
    – I'll Eat My Hat
    Nov 10 at 18:21














up vote
3
down vote

favorite
2












I find that the autocomplete for Flask is somewhat lacking--this is because internally, context-specific objects such as current_app, request, and logger are actually LocalProxys. Thus PyCharm reasonably has no idea what to do with this type.



So the obvious solution to this, to me would be to apply type hints on the imported modules. Except you can't do that! As of Python 3.7 there appears to be no such syntax to facilitate this.



So the next-obvious solution would be to make local copies of each context-specific module with the type explicitly set like so:



from logging import Logger
from flask import Flask, Request, Blueprint, request, current_app as app

app: Flask = app
logger: Logger = app.logger
request: Request = request


...which works until you actually attempt to start the server, in which case the application crashes because of a RuntimeError: Working outside of application context.



It turns out that we can actually encapsulate the relevant type hints inside of a class or other scope inside of the application context.



@foo_blueprint.route('/foo', methods=['GET'])
def foo(cls):
_app: Flask = app
_logger: Logger = app.logger
_request: Request = request
# ...


...which works but is incredibly awkward in every imaginable sense.



Is there a reasonable solution for getting proper type hints inside of an application context in Flask?










share|improve this question





















  • maybe it will be useful
    – Danila Ganchar
    Nov 9 at 8:42










  • Flask is only supported in the professional edition of Pycharm jetbrains.com/help/pycharm/flask.html Which version of Pycharm are you using: Community Edition or Professional?
    – Eskapp
    Nov 9 at 16:01










  • I use the Community Edition (was not aware of dedicated support of particular libraries), but this question was written in general for those awful libraries that smash together types at runtime (such as Boto3).
    – I'll Eat My Hat
    Nov 10 at 18:13










  • cont'd: Flask as an example was merely the latest, most widely used, and has what is probably the simplest problems and workarounds.
    – I'll Eat My Hat
    Nov 10 at 18:21












up vote
3
down vote

favorite
2









up vote
3
down vote

favorite
2






2





I find that the autocomplete for Flask is somewhat lacking--this is because internally, context-specific objects such as current_app, request, and logger are actually LocalProxys. Thus PyCharm reasonably has no idea what to do with this type.



So the obvious solution to this, to me would be to apply type hints on the imported modules. Except you can't do that! As of Python 3.7 there appears to be no such syntax to facilitate this.



So the next-obvious solution would be to make local copies of each context-specific module with the type explicitly set like so:



from logging import Logger
from flask import Flask, Request, Blueprint, request, current_app as app

app: Flask = app
logger: Logger = app.logger
request: Request = request


...which works until you actually attempt to start the server, in which case the application crashes because of a RuntimeError: Working outside of application context.



It turns out that we can actually encapsulate the relevant type hints inside of a class or other scope inside of the application context.



@foo_blueprint.route('/foo', methods=['GET'])
def foo(cls):
_app: Flask = app
_logger: Logger = app.logger
_request: Request = request
# ...


...which works but is incredibly awkward in every imaginable sense.



Is there a reasonable solution for getting proper type hints inside of an application context in Flask?










share|improve this question













I find that the autocomplete for Flask is somewhat lacking--this is because internally, context-specific objects such as current_app, request, and logger are actually LocalProxys. Thus PyCharm reasonably has no idea what to do with this type.



So the obvious solution to this, to me would be to apply type hints on the imported modules. Except you can't do that! As of Python 3.7 there appears to be no such syntax to facilitate this.



So the next-obvious solution would be to make local copies of each context-specific module with the type explicitly set like so:



from logging import Logger
from flask import Flask, Request, Blueprint, request, current_app as app

app: Flask = app
logger: Logger = app.logger
request: Request = request


...which works until you actually attempt to start the server, in which case the application crashes because of a RuntimeError: Working outside of application context.



It turns out that we can actually encapsulate the relevant type hints inside of a class or other scope inside of the application context.



@foo_blueprint.route('/foo', methods=['GET'])
def foo(cls):
_app: Flask = app
_logger: Logger = app.logger
_request: Request = request
# ...


...which works but is incredibly awkward in every imaginable sense.



Is there a reasonable solution for getting proper type hints inside of an application context in Flask?







python flask pycharm type-hinting python-3.7






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share|improve this question











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share|improve this question










asked Nov 9 at 8:10









I'll Eat My Hat

1388




1388











  • maybe it will be useful
    – Danila Ganchar
    Nov 9 at 8:42










  • Flask is only supported in the professional edition of Pycharm jetbrains.com/help/pycharm/flask.html Which version of Pycharm are you using: Community Edition or Professional?
    – Eskapp
    Nov 9 at 16:01










  • I use the Community Edition (was not aware of dedicated support of particular libraries), but this question was written in general for those awful libraries that smash together types at runtime (such as Boto3).
    – I'll Eat My Hat
    Nov 10 at 18:13










  • cont'd: Flask as an example was merely the latest, most widely used, and has what is probably the simplest problems and workarounds.
    – I'll Eat My Hat
    Nov 10 at 18:21
















  • maybe it will be useful
    – Danila Ganchar
    Nov 9 at 8:42










  • Flask is only supported in the professional edition of Pycharm jetbrains.com/help/pycharm/flask.html Which version of Pycharm are you using: Community Edition or Professional?
    – Eskapp
    Nov 9 at 16:01










  • I use the Community Edition (was not aware of dedicated support of particular libraries), but this question was written in general for those awful libraries that smash together types at runtime (such as Boto3).
    – I'll Eat My Hat
    Nov 10 at 18:13










  • cont'd: Flask as an example was merely the latest, most widely used, and has what is probably the simplest problems and workarounds.
    – I'll Eat My Hat
    Nov 10 at 18:21















maybe it will be useful
– Danila Ganchar
Nov 9 at 8:42




maybe it will be useful
– Danila Ganchar
Nov 9 at 8:42












Flask is only supported in the professional edition of Pycharm jetbrains.com/help/pycharm/flask.html Which version of Pycharm are you using: Community Edition or Professional?
– Eskapp
Nov 9 at 16:01




Flask is only supported in the professional edition of Pycharm jetbrains.com/help/pycharm/flask.html Which version of Pycharm are you using: Community Edition or Professional?
– Eskapp
Nov 9 at 16:01












I use the Community Edition (was not aware of dedicated support of particular libraries), but this question was written in general for those awful libraries that smash together types at runtime (such as Boto3).
– I'll Eat My Hat
Nov 10 at 18:13




I use the Community Edition (was not aware of dedicated support of particular libraries), but this question was written in general for those awful libraries that smash together types at runtime (such as Boto3).
– I'll Eat My Hat
Nov 10 at 18:13












cont'd: Flask as an example was merely the latest, most widely used, and has what is probably the simplest problems and workarounds.
– I'll Eat My Hat
Nov 10 at 18:21




cont'd: Flask as an example was merely the latest, most widely used, and has what is probably the simplest problems and workarounds.
– I'll Eat My Hat
Nov 10 at 18:21

















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