CXone Studio: Authenticating GetRESTProxy calls with client_credentials

Quick question about securing outbound API calls from within a CXone Studio script. I am trying to invoke a downstream service using the GetRESTProxy snippet, but I need to first acquire an OAuth2 access token using the client_credentials grant type.

The challenge is that GetRESTProxy does not appear to have a built-in method for performing the initial POST to /oauth/token. I have attempted to chain a GetRESTProxy call to fetch the token, extract the access_token string using GetJSONValue, and then inject it into the Authorization header of the subsequent business logic call. However, the token retrieval step consistently fails with a 401 Unauthorized error, likely because I am mishandling the Basic Auth header generation within the snippet’s limited string manipulation capabilities.

“The client_credentials grant requires the client_id and client_secret to be passed as Base64-encoded Basic Auth credentials in the Authorization header of the POST request to the token endpoint.”

Is there a recommended pattern for handling this two-step authentication flow entirely within Studio? Or should I be routing this through a middleware layer to handle the token exchange before the script execution? Here is my current attempt at the token fetch configuration:

{
 "method": "POST",
 "url": "https://api.nice.incontact.com/oauth/token",
 "headers": {
 "Content-Type": "application/x-www-form-urlencoded"
 },
 "body": "grant_type=client_credentials&scope=api"
}

The root cause here is the misunderstanding that GetRESTProxy requires a pre-authenticated session rather than facilitating the authentication handshake itself. In CXone Studio, you must explicitly chain the token acquisition. First, configure a GetRESTProxy step to POST to /oauth/token with your client_id and client_secret in the body. Capture the resulting access_token into a temporary variable. Crucially, ensure you handle potential JSON parsing errors if the token request fails, as subsequent calls will inherit this failure. Next, invoke a second GetRESTProxy instance for your target downstream API. In the headers configuration, dynamically assign the captured token to the Authorization header using the syntax Bearer ${tempTokenVar}. This two-step pattern ensures that every outbound request carries a valid, fresh credential derived from your client credentials grant, maintaining strict security compliance within the flow execution context.