How to identify and save the right "user" when we use Django (Existing proj) for authentication and FastAPI (new feature) for API's?

user_13197161 0
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Hello guys I have an existing Django project which has certain features and also has user data. For certain features, users use the API served through Django (also the authentication), but since there is a need for new feature which needs to be implemented through FastAPI, I need to have the same users authenticate or (better to say) to be recognized by FastAPI (as the same user in Django) to save or retrieve an action corresponding to user in the db (through FastAPI).

How to achieve that? How do I store the user data, like user_id and username for each user safely? How to properly design the database table?

Please do let me know, how to start.

Thank you.

django-rest-framework fastapi python-3.x django-models django
2 Answers

Assuming you've implemented your own AbstractUser sub-class named DannyUser, you then have a couple of choices:

  • Embed all of the information needed into a new field (a JSONField subclass for example) -- not really recommended as this leaks random information into a housekeeping table and is ill-advised IMO.

  • Design a new Model for each authentication service and tie it via a foreign key & reverse relationship to your DannyUser instances. Then you could use something like my_danny_instance.fastapi_account.auth_token where needed. This will also allow you to encrypt specific fields or use a secret management solution later on.

Simply normalize your data as far as it makes sense to.

user_45460020

This is mostly a software architecture design problem, In your old login endpoint put every required data by the new FastAPI project in the JWT token payload(such as user_id, user_name and etc), sign it and give it to the user:

# using PyJWT
import jwt
user_token = jwt.encode(
     {"user_id": "1222", "user_name": "yosef", },
     "YOUR_SECRET_KEY",
     algorithm="HS256",
     headers={},
)

Afterwards in new FastAPI project endpoint, validate JWT token in request header with the key you have signed it in Django login endpoint:

# using PyJWT
import jwt

try:
    data = jwt.decode(JWT_STRING_VAR, "YOUR_SECRET_KEY", algorithms=["HS256"])
except jwt.ExpiredSignatureError:
    # reject
    ...

If the token is valid you accept the request and use the payload as confirmed data to do your usual endpoint functionality and if sign is not valid reject request.
This way you are not required to change your old endpoints at all.
*note: instead of PyJWT you can use SimpleJWT or any other package for Django and a suitable JWT package for FastAPI
**note: this scenario may go crazy complex when your JWT payload may get changed before the JWT expires, like when user_name changes but you can not change that in JWT and user can use it in your other service with old data, there are more solutions on this, like removing the properties that may change from payload and get them directly from database, meaning you query Django populated table from FastAPI, you can achieve this by import dynamic tables in SQLAlchemy ***note: system design schema image enter image description here

user_121312340
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