Issue with Literal Type Hint in Mypy

[Revox179]

Hey everyone, I’m having an issue with a Literal type hint in Python. I have the following class:

from typing import Literal

class Account(
    id: str,
    email: str,
    username: str,
    pterodactyl_id: int,
    hosting_plan: Literal['free', 'premium', 'sponsor'] = 'free'
)

Somewhere else in my code, I define the variable new_plan like this:

new_plan = "free" if account["server_booster"] is False else "premium"

Since new_plan is always either "free" or "premium", Visual Studio Code correctly infers its type as Literal["free", "premium"]:

However, when I pass new_plan to the Account initialization, Mypy throws this error:

Argument 5 to "Account" has incompatible type "str"; expected "Literal['free', 'premium', 'sponsor']"

I’m really confused about why this happens. Is this a bug in Mypy, or am I missing something?

[Akuli]

In mypy, the type of new_plan is str. (You can see it if you add reveal_type(new_plan) to your code and run mypy.) Here's how to work around that:

new_plan: Literal["free", "premium"] = "free" if account["server_booster"] is False else "premium"

[Revox179]

Oh yes, that's fixed the error! Thanks for the help. I'll use reveal_type next time, I didn't know that yet, although it's really useful, thanks for that tip!