如何使用 OAuth2.0 请求访问令牌？

Question

I'm still learning on how to use REST API. Right now I want to integrate a FatSecret Rest API for my mobile apps development. I'm currently stuck at step 2 here .

This is my current code which I referred from HERE (under CLIENT CREDENTIALS GRANT TYPE section):

import requests, json
import urllib3

urllib3.disable_warnings()

token_url = "https://oauth.fatsecret.com/connect/token"

test_api_url = "https://platform.fatsecret.com/rest/server.api"

#client (application) credentials 
client_id = "<CLIENT_ID>"
client_secret = "<CLIENT_SECRET>"

#step A, B - single call with client credentials as the basic auth header - will return access_token
data = {'grant_type': 'client_credentials',
        'scope': 'basic'}

access_token_response = requests.post(token_url, data=data, verify=False, allow_redirects=False, auth=(client_id, client_secret))

print(access_token_response.headers)
print(access_token_response.text)
print(access_token_response.status_code)

tokens = json.loads(access_token_response.text)

print("access token: " + tokens['access_token'])

#step B - with the returned access_token we can make as many calls as we want

api_call_headers = {'Authorization': 'Bearer ' + tokens['access_token']}
api_call_response = requests.get(test_api_url, headers=api_call_headers, verify=False)

print(api_call_response.text)

But I got these errors:

{'Date': 'Wed, 03 Nov 2021 14:13:17 GMT', 'Content-Type': 'application/json; charset=UTF-8', 'Transfer-Encoding': 'chunked', 'Connection': 'keep-alive', 'Set-Cookie': 'AWSALB=ulzLdAF+yzvlb1zyySg3WOSoBgvDZVL924yxgKUcgcXfDccOCZVe+toy32y9oHStYz3ljYQBgSuXCZvC5bKSALd5nRVnsmb/kOipLY7EcSG5qUjcDUkkfkRxbtjj; Expires=Wed, 10 Nov 2021 14:13:16 GMT; Path=/, AWSALBCORS=ulzLdAF+yzvlb1zyySg3WOSoBgvDZVL924yxgKUcgcXfDccOCZVe+toy32y9oHStYz3ljYQBgSuXCZvC5bKSALd5nRVnsmb/kOipLY7EcSG5qUjcDUkkfkRxbtjj; Expires=Wed, 10 Nov 2021 14:13:16 GMT; Path=/; SameSite=None; Secure', 'Cache-Control': 'no-store, no-cache, max-age=0', 'Pragma': 'no-cache', 'Server': 'Kestrel', 'X-Powered-By': 'ASP.NET'}
{"error":"invalid_client"}
400
---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<ipython-input-24-9611470e9c26> in <module>()
     24 tokens = json.loads(access_token_response.text)
     25 
---> 26 print("access token: " + tokens['access_token'])
     27 
     28 #step B - with the returned access_token we can make as many calls as we want

KeyError: 'access_token'

I've already tried some other solutions on this platform but most of them would return this error like {"error":"invalid_request"} or {"error":"invalid_client"}.

I'm not sure what went wrong? Is it the OAuth2.0? Should I use other oauth? Can someone kindly help me how to get through this. Thank you in advance.

Answer 1

Two things:

1. The error (invalid_client) sounds like the client_id is not recognized by the service. I would suggest trying curl (see the example they listed) to make sure the service provides a good response to your credentials before trying to get it to work in your script.

2. Without seeing the variable "tokens", I cannot tell if the JSON conversion was successful or not. I would check the type of tokens to see if the JSON was successfully converted and if that key exists.