Accessing Payload Data

When working with routes, it's often necessary to access data from a payload. This guide will show you how to accomplish this using Authx.

Authx introduces the TokenPayload class, a Pydantic BaseModel designed to handle JWT claims and operations. When Authx generates a token, it can be serialized into an easy-to-use TokenPayload instance.

Storing Additional Data

By default, the authx.create_[access|refresh]_token methods handle standard JWT claims such as issue date, expiry time, and issuer identity. However, you can store additional data by passing keyword arguments to these methods.

For instance:

token = security.create_access_token(uid="USER_UNIQUE_IDENTIFIER", foo="bar")

Keep in mind that the additional data passed as keyword arguments must be JSON serializable. Failure to adhere to this requirement will result in a TypeError. For example:

from datetime import datetime
security.create_access_token(uid="USER_UNIQUE_IDENTIFIER", foo=datetime(2023, 1, 1, 12, 0))

Accessing Data in Routes

JWT authentication allows you to scope an endpoint's logic to a specific user or recipient without explicitly referencing them. This is particularly useful for endpoints like /me or /profile.

To access data within your routes, you can use the authx.access_token_required dependency. When used as a parameter dependency, it returns a TokenPayload instance from a valid JWT. This payload can then be used to retrieve user data within your route logic.

However, using authx.access_token_required as a function dependency may lead to code repetition and the inclusion of fetching code outside your route logic.

Here's an example of how to use authx.access_token_required in a FastAPI application:

from fastapi import FastAPI, Depends
from authx import AuthX, TokenPayload, AuthXConfig

app = FastAPI()
config = AuthXConfig()
config.JWT_SECRET_KEY = "SECRET_KEY"
security = AuthX(config=config)

@app.get('/token')
def get_token():
    token = security.create_access_token(uid="USER_ID", foo="bar", age=22)
    return {"access_token": token}

@app.get('/profile')
def get_profile(payload: TokenPayload = Depends(security.access_token_required)):
    return {
        "id": payload.sub,
        "age": getattr(payload, "age"),
        "foo": getattr(payload, "foo"),
    }

In this example, the get_token endpoint generates a token, while the get_profile endpoint utilizes authx.access_token_required to retrieve and utilize the token payload within its logic.

Whether used as a function argument or a route/decorator argument, authx.access_token_required enforces the validity of the token, throwing an exception if the token is invalid.

With access to the payload object, you can incorporate additional fields included with authx.create_[access|refresh]_token into your route logic.