TypeError: 'Request' object does not support item assignment

I’m creating an API gateway using fastAPI for some microservices, which in I authenticate user via Azure AD via this library. So I’m trying to take out the user info from the request object (request.state.user) and inject my own token in it to later pass to other microservices. I can’t do this in middleware, cause user info is getting added after it. But I tried creating an decorator:

from functools import wraps

def token_injector(function):
    @wraps(function)
    def wrap_function(*args, **kwargs):
        user: User = kwargs['request'].state.user
        new_token = generate_token(user)
        kwargs["new_token"] = new_token # or kwargs['request']["new_token"] = new_token
        return function(*args, **kwargs)
    return wrap_function

and for this approach, I’m getting these errors:

ValueError: [TypeError("'coroutine' object is not iterable"), TypeError('vars() argument must have dict attribute')] and

TypeError: 'Request' object does not support item assignment

Can you please guide me how did you inject user in request.state, so I can do the same?

[JonasKs]

Hi! Thank you for following up letting me know it’s been resolved. I don’t have enough reputation on SO to follow up there.

There are a few questions here, so I’ll try to answer them as best as I can. Let me know if anything is unclear.

First off, I agree with the approach you’ve landed on. Chaining dependencies is the way to make sure something is “in the right order”. It is also the approach I’ve described in the docs here, and also deomonstrated in the demo project in this view, using this dependency.

The user model is defined here, and is created here.

I would recommend you to not “get rid of” the User object, but maybe create your own user model and append to it. Here’s an example:

from pydantic import Field
from fastapi_azure_auth.user import User
from typing import Optional

class CustomUser(User):
    new_token: Optional[str] = Field(default=None)

and then in your own dependency do this:

from fastapi import Depends
from fastapi_azure_auth.auth import InvalidAuth
from fastapi_azure_auth.user import User

async def new_user(user: User = Depends(azure_scheme)) -> CustomUser:
    new_token = 'ey....'
    new_user = CustomUser(**user.dict() | {'new_token': new_token})

I hope this code runs (I haven’t been able to test it), but if not, let me know and I’ll write a real example for you tomorrow.

[JonasKs]

Ah, yes, I forgot about that part of the question 👍