Python mypy don't type check dataclass-CodePudding

mypy works perfectly with type hints but when I use a dataclass as return type it don't check the type

My command : python -m pipenv run mypy .

@dataclass
class HttpMessageModel:
    message: str
    code: int

def http_message(message: str) -> HttpMessageModel:
    return {
        "message": message,
        "code": "200", # --> should fail since we have a int
    }

full code exemple : https://github.com/TheSmartMonkey/create-python-app

CodePudding user response：

If I put your code in a single file:

from dataclasses import dataclass

@dataclass
class HttpMessageModel:
    message: str
    code: int

def http_message(message: str) -> HttpMessageModel:
    return {
        "message": message,
        "code": "200", # --> should fail since we have a int
    }

and run mypy on it, I do get the expected error:

C:\test\python>mypy test.py
test.py:9: error: Incompatible return value type (got "Dict[str, str]", expected "HttpMessageModel")

The problem with checking your actual project might be in how the directory structure is set up. Take a look at https://mypy.readthedocs.io/en/latest/running_mypy.html#mapping-file-paths-to-modules and try either adding __init__.py files at the root of your package directories or adding namespace_packages = True to your mypy config.

Note that to return an HttpMessageModel instead of a dict, your function should do:

def http_message(message: str) -> HttpMessageModel:
    return HttpMessageModel(message, 200)