Generating OAuth2.0 token with grantType Code without manual intervention

Not sure if this topic is already posted. It was hard to find the scenario what I am looking for, hence posting as a new topic.

We have many APIs which have different behavior for different roles set for the user. If I want to test these APIs for different user roles, I need to change the user credentials and verify the behavior. My questions are :

  1. How to I automate generation of OAuth2.0 token using user login details. I want to use the Collection Runner to run my tests, hence no manual intervention to enter user login details is expected in the flow.
  2. For one of the client, we have the grantType as ClientCredentials and I can automate without manual intervention to generate the OAuth2.0 token using the clientId/clientSecret and use it in all my scripts by setting the token in a global variable. For another client, we have grantType as Code and when I use this client in postman Authorization , it takes me to user credentials screen to enter my login details. This is the flow , I am looking to automate so that I can generate token for different user roles and run my tests appropriately.

Any help is much appreciated.



Any updates on this please?