How can I authenticate by rest api oauth2

[umeshhodwala]

Formatters were not ok, I defined formatters by this post and it is working-

Custom Client Side Formatters Issue

Thanks @patrick but returned error ; [client1] <script> dmx.Formatters('string', { encodeBase64: function(val) { return btoa(val); }, decodeBase64: function(val) { return atob(val); } }); </script>

However now i am getting 500 errors

I think the problem is how to pass grant_type etc in data. I checked with following variations-
grant_type=password
username=admin
password=admin

or body =grant_type=password&username=admin&password=admin

or Form data_type is not available in AC api action as in SC api action (where it is working)
regards