Type from settings not correctly loaded in a model

[lfrodrigues]

Bug report

I have this in settings:

BANK_ENTITIES = [('a', 'A Bank'), ('b', 'B Bank'),]

and this in my model:

entity = models.CharField(max_length=20, choices=settings.BANK_ENTITIES, blank=True)

What's wrong

mypy fails with:

models.py:247: error: Argument "choices" to "CharField" has incompatible type "tuple"; expected "Optional[Iterable[Union[Tuple[Any, Any], Tuple[str, Iterable[Tuple[Any, Any]]]]]]"

If I place a reveal in settings and another in models.py I get

settingsbase.py:90: note: Revealed type is 'builtins.list[Tuple[builtins.str, builtins.str]]'
models.py:214: note: Revealed type is 'builtins.list'

How is that should be

mypy should be able to load the full type from settings, not only that it's a list

System information

• OS: Ubuntu 18.04
• python version: 3.6
• django version: 2.2
• mypy version: 0.761
• django-stubs version: 1.4.0

[sobolevn]

Can you please post the result of reveal_type(BANK_ENTITIES) inside your settings and reveal_type(settings.BANK_ENTITIES) inside your models?

[lfrodrigues]

I posted it in the initial report:

settingsbase.py:90: note: Revealed type is 'builtins.list[Tuple[builtins.str, builtins.str]]'
models.py:214: note: Revealed type is 'builtins.list'

[sobolevn]

Oh, sorry, I have missed it. Yes, looks like a bug!
Thanks for the report.

[AdrienLemaire]

Getting the same issue. Is there a plan to fix it @sobolevn ?

settings:

class POINTS:
    a = 1
    b = 20
    c = 5

models.py

from django.conf import settings
reveal_type(settings.POINTS)   #  Revealed type is 'builtins.type'
settings.POINTS.a  # [mypy error] [E] "type" has no attribute "a"

EDIT: Actually, my situation is explained in https://mypy.readthedocs.io/en/stable/metaclasses.html, and I was not defining a metaclass. Sorry for the disturb.

[kszmigiel]

@lfrodrigues could you verify if this bug still occurs? I wasn't able to reproduce it at all. I guess that someone fixed this in the meantime, or maybe your mypy.ini file wasn't properly configured.

[lfrodrigues]

I just tested it again. If I just have a simple settings.py file like the one created when django starts a project there is no problem.

The problem is that my settings import different sub modules for settings depending on the country that was configured.

Here's a demo repository:
https://github.com/lfrodrigues/testdjangotypes

from django.conf import settings

def view():
    a = settings.MY_SETTINGS['item']['subitem']

~/tmp/demo_error/src$ mypy app1/
app1/views.py:9: error: Value of type "_VT" is not indexable

[kszmigiel]

@lfrodrigues Thank you for the tips, I'll try to fix this as soon as I have enough time.

[anentropic]

I think I have a related issue

# settings.py
SOME_DICT = {
    'a': 'whatever',
    'b': 'whatever',
    'c': 'whatever',
}

# myproject/mymodule.py
from django.conf import settings

whatever = settings.SOME_DICT["b"]

and mypy gives the following error:

myproject/mymodule.py:3: error: Invalid index type "str" for "dict"; expected type "_KT"

The _KT TypeVar appears to be defined in mypy typeshed in relation to Mapping container, i.e. for dicts

Adding an annotation to the settings like this does not help:

# settings.py
from typing import Dict

SOME_DICT: Dict[str, str] = {
    'a': 'whatever',
    'b': 'whatever',
    'c': 'whatever',
}

The problem is that my settings import different sub modules for settings depending on the country that was configured.

we also have similar situation with conditional import of sub-module settings, maybe is relevant

(my example code above is simplified so might not reproduce the issue by itself)

I am able to make mypy happy with the following workaround:

# myproject/mymodule.py
from typing import Dict
from django.conf import settings

_some_dict: Dict[str, str] = settings.SOME_DICT

whatever = _some_dict["b"]

(and no annotation in settings.py)

[anentropic]

this looks the same #352

[BeWe11]

I am experiencing the same bug with django-stubs 1.8.0 and django-stubs-ext 0.2.0. Defining dictionaries in a settings file and than importing them via django.conf.settings loses the type annotation, e.g.

# in settings.py
mydict = {"a": ["b", "c"]}
reveal_type(mydict) -> builtins.dict[builtins.str*, typing.Sequence*[builtins.str]]

becomes

# in other.py
from django.conf import settings
reveal_type(settings.mydict) -> builtings.dict

[RJPercival]

@kszmigiel, are you still intending to fix this or should it be unassigned?