system.net.httpPost() throwing error while Postman is not

Ignition
,
1

I’m having trouble using the system.net.httpPost() function to POST a message to an endpoint. I can use Postman and get the response I need but when I try to use httpPost() I get an error message {"error": "unsupported_grant_type"}.

I am wondering what I am doing differently in Postman vs Ignition that it doesn’t work.

Here is my script:

def getAccessToken():
	headers = {"Content-Type": "application/x-www-form-urlencoded","Accept": "*/*","Accept-Encoding": "gzip, deflate, br","Connection": "keep-alive"}
	
	body = {"grant_type": "refresh_token","refresh_token": getRefreshToken()}
	
	contentType = "application/x-www-form-urlencoded"
	
	url = getWebServicesRootUrl() + '/services/rest/auth/oauth2/v1/token'

	res = system.net.httpPost(url, 
				contentType = contentType, 
				postData = body, 
				username = getClientId(), 
				password = getClientSecret(), 
				headerValues = headers, 
				throwOnError = False
			)
	return res

Here is what the headers look like in Postman:
image

Here is what the body looks like in Postman:
image

Here is the Authorization in Postman (that corresponds to username and password in system.net.httpPost(), at least that is what I assumed…):

image
image1084×266 17.4 KB

Here are Postman settings:

image
image887×712 68.1 KB

Any feedback will be greatly appreciated. I also tried using system.net.httpClient() but got the same response code.

2

Try using system.net.httpClient() instead. system.net.httpPost() doesn’t know how to encode that dictionary you provide for the body into x-www-form-urlencoded. Or do that encoding to the body yourself and pass the resulting string in as the body.

edit: actually not sure if system.net.httpClient() will do that encoding for you either.

1 Like
3

Hi Kevin,

Thanks for the quick response… That ended up being the issue.

Quick fix:

  1. Add import statement from urllib import urlencode.
  2. Call function urlencode() on body parameter.

Full function:

def getAccessToken():
	from urllib import urlencode
	headers = {"Content-Type": "application/x-www-form-urlencoded","Accept": "*/*","Accept-Encoding": "gzip, deflate, br","Connection": "keep-alive"}
	
	body = {"grant_type": "refresh_token","refresh_token": getRefreshToken()}
	
	contentType = "application/x-www-form-urlencoded"
	
	url = getWebServicesRootUrl() + '/services/rest/auth/oauth2/v1/token'

	res = system.net.httpPost(url, 
				contentType = contentType, 
				postData = urlencode(body), 
				username = getClientId(), 
				password = getClientSecret(), 
				headerValues = headers, 
				throwOnError = False
			)
	return res
1 Like
4

From my experience, it didn't. Thank you for your answer, that was the breakthrough I needed.

@Kevin.Herron I should probably open another thread, but I have one last question: I have a follow up HTTP POST that I need to make that has the Authorization type Bearer Token. Is there a way to use system.net.httpPost() to make this request? From the documentation, it isn't immediately clear that system.net.httpClient() would support it either, or that it would be any different than httpPost().

1 Like
5

I think the only way to make that work would be put all the appropriate headers in yourself.

@PGriffith that sound right?

6

Yeah, that’s correct. The JDK HttpClient only supports Basic auth for now (with some vague idea of future support for other auth types).

And better support for form encoding in POST submissions is a planned feature, but no timeline on that.

7

I had to import the urlencode function of the urllib library to encode the data being passed in. The get open cases method of the API was a little more straight forward (no explicit encoded required). Hence I was able to get this working.
Thanks Paul!

1 Like
8

OOPS! Wrong thread! :slight_smile: