system.net.httpClient().post throwing 'unsupported_grant_type' error

Ignition
, ,
1

I am using system.net.httpClient().post to issue a refresh token but for some reason I am getting an ‘unsupported_grant_type’ error. Here’s my code:

from base64 import b64encode
logger = system.util.getLogger("myLogger")


client_id = system.tag.read("[WFM_API]client_id").value
client_secret =  system.tag.read("[WFM_API]client_secret").value
AccessToken = system.tag.read("[WFM_API]Tokens/AccessToken").value
scope = system.tag.read("[WFM_API]scopes").value
redirect_url = 'https://xero.com/'
RefreshToken = system.tag.read("[WFM_API]Tokens/RefreshToken").value

b64_id_secret = b64encode(client_id + ':' + client_secret)

def XeroRefreshToken(refresh_token):
   token_refresh_url = 'https://identity.xero.com/connect/token'
   client = system.net.httpClient()
   response = client.post(token_refresh_url,
                           headers = {
                               'Authorization' : 'Basic ' + b64_id_secret,
                               'Content-Type': 'application/x-www-form-urlencoded'
                           },
                           data = {
                               'grant_type' : 'refresh_token',
                               'refresh_token' : refresh_token
                           })
   json_response = response.json
   print json_response
   logger.info(str(json_response))
   
XeroRefreshToken(RefreshToken)

I’ve also tried using the system.net.httpPost function and that returned the same error too.
I used the urlencode function on the “body” parameter by referring to this post here, but that also threw the same error. Any help is much appreciated.

Ignition Version 8.1.16

2

Do you have any documentation on what this API actually expects?

3

Yes, and I think I am doing it right. This is what they’re expecting Refreshing access & refresh tokens. I also forgot to mention that I am having no issues refreshing the token using postman.
Here are the headers:

image
image1485×551 51.2 KB

Body:

image
image1484×461 27 KB

Settings:

image
image1491×788 77.3 KB

4

I don’t think either of the system.net methods can automatically encode your payload as “form-data” or “application/x-www-form-urlencoded” data.

You’re passing in a dictionary and it’s almost certainly just being encoded as a JSON object and sent off as the body.

You may need to manually concatenate the payload into a String with the correct format instead.

5

I tried urlencoding my ‘data’ argument and also tried using it as a string and both times I got a
{‘error’: u’invalid_grant’}

URL Encoding:

def XeroRefreshToken(refresh_token):
from urllib import urlencode
token_refresh_url = 'https://identity.xero.com/connect/token'
	client = system.net.httpClient()
	response = client.post(token_refresh_url,
                            headers = {
                                'Authorization' : 'Basic ' + b64_id_secret,
                                'Content-Type': 'application/x-www-form-urlencoded'
                            },
                            data = urlencode({
                                'grant_type' : 'refresh_token',
                                'refresh_token' : refresh_token
                            }))
	json_response = response.json
	print json_response

Concatenating in a string:

def XeroRefreshToken(refresh_token):
	token_refresh_url = 'https://identity.xero.com/connect/token'
	client = system.net.httpClient()
	response = client.post(token_refresh_url,
                            headers = {
                                'Authorization' : 'Basic ' + b64_id_secret,
                                'Content-Type': 'application/x-www-form-urlencoded'
                            },
                            data = 'grant_type=refresh_token&refresh_token=%s'%refresh_token
                            )
	json_response = response.json
	print json_response
	
XeroRefreshToken(RefreshToken)```
6

Try URL-encoding this String you build:

'grant_type=refresh_token&refresh_token=%s'%refresh_token

Your two examples are either URL-encoding the string representation of a dictionary or not URL encoding the data at all.

7

My bad, thought I only had to encode the dictionary. Looks like urlencode only works with dictionaries because it was returning TypeError: not a valid non-string sequence or mapping object when I was using it with a string. Did some research and it looks like I have to use urllib.quote or urllib.quote_plus with a string and non of them worked. Both returned {'error': u'unsupported_grant_type'}

8

Hmm, well I just looked at the docs for urlencode, and you can pass it a dictionary, which I didn’t know.

I’m assuming you can’t access the URL via plain HTTP, so you might need to get some kind of local HTTP mitm/dev proxy set up that will let you see what the difference between what you’re sending via Postman and Ignition is.

9

Just figured it out! I clicked on the code snippet icon </> in PostMan and selected the ‘Python - http.client’ option from the dropdown. I saw that the code was importing the encode module from a library called codecs. So I tried it out and system.net.httpClient().post is returning the expected response now. My script became like this:


client_id = system.tag.read("[WFM_API]client_id").value
client_secret =  system.tag.read("[WFM_API]client_secret").value
AccessToken = system.tag.read("[WFM_API]Tokens/AccessToken").value
scope = system.tag.read("[WFM_API]scopes").value
redirect_url = 'https://xero.com/'
RefreshToken = system.tag.read("[WFM_API]Tokens/RefreshToken").value

b64_id_secret = b64encode(client_id + ':' + client_secret)

def XeroRefreshToken(refresh_token):
	from codecs import encode
	token_refresh_url = 'https://identity.xero.com/connect/token '
	client = system.net.httpClient()
	response = client.post(token_refresh_url,
                            headers = {
                                'Authorization' : 'Basic ' + b64_id_secret,
                                'Content-Type': 'application/x-www-form-urlencoded'
                            },
                            data = encode('grant_type=refresh_token&refresh_token=%s'%refresh_token)
                            )
	json_response = response.json
	print json_response	

XeroRefreshToken(RefreshToken)

Thanks Kevin for your help.

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