I did build a microflow that executes OAuth authentication a few months ago using a standard REST call with POST method, here is my example:
The input values were not as straight forward as I thought, I tested it for a while using postman before finding the correct values. For example, the request body required an extra field “undefined” but I cannot find the notes explaining why:
I hope that helps.
You can authenticate with OAuth2 – I just built a Microsoft Graph integration using (Microsoft’s version) of OAuth2.
I used the following from the appstore: URL Redirector, Model Reflection, Deeplink
The general steps are as follows:
For reference, the DeepLink I defined for step 2 looks like this:
Also, it has the query params because the microflow looks like this:
The string params of the microflow are used as the query params of the Deeplink.
Hope that will help you get you started.
What exactly are you running into?
You should be able to perform the authorization calls using a consume REST Service activity in Mendix: https://docs.mendix.com/howto/integration/consume-a-rest-service
How the OAuth2 specifically works it not really specific Mendix question, I think there's enough to find about that on the internet…