Accessing request headers in flask-restless preprocessor

flask, flask-restless, python

Solution

In a normal Flask request-response cycle, the `request` context is active when the Flask-Restful preprocessors and postprocessors are being run.

As such, using:

from flask import request, abort

def check_auth(instance_id=None, **kw):
    current_user = None
    auth = request.headers.get('Authorization', '').lower()
    try:
        type_, apikey = auth.split(None, 1)
        if type_ != 'your_api_scheme':
            # invalid Authorization scheme
            ProcessingException(message='Not Authorized',
                                status_code=401)
        current_user = user_for_apikey[apikey]       
    except (ValueError, KeyError):
        # split failures or API key not valid
        ProcessingException(message='Not Authorized',
                            status_code=401)

should Just Work.

Problem

I'm building an API with Flask-Restless that requires an API key, that will be in the `Authorization` HTTP header. In the Flask-Restless example here for a preprocessor: ``` def check_auth(instance_id=None, **kw): # Here, get the current user from the session. current_user = ... # Next, check if the user is authorized to modify the specified # instance of the model. if not is_authorized_to_modify(current_user, instance_id): raise ProcessingException(message='Not Authorized', status_code=401) manager.create_api(Person, preprocessors=dict(GET_SINGLE=[check_auth])) ``` How do I retrieve the `Authorization` header in the `check_auth` function? I have tried accessing the Flask `response` object, but it is `None` during the scope of this function. The `kw` parameter is also an empty dict.

Original source