Apex Rest callout for Access token - rest

Question

I want to generate a simple post call from Apex for the access token. I am new to Apex and Rest so is there someone explain me how to do that?
I have endpointurl, client _secret, client_id, scope, and grant_type is Client_credentials'.
I tried to run this in Postman and it works fine but not in salesforce.
Http http = new Http();
HttpRequest request = new HttpRequest();
request.setEndpoint('https://xxx.xxx.eu/o/oauth2/token');
string mybody='{"client_id":"xxxx","client_secret":"xxxx","grant_type":"client_credentials","scope": "xxx.Rest.everything"}';
request.setMethod('POST');
request.setHeader('Content-Type', 'application/json;charset=UTF-8');
// Set the body as a JSON object
request.setBody(mybody);
HttpResponse response = http.send(request);
// Parse the JSON response
if (response.getStatusCode() != 201) {
System.debug('The status code returned was not expected: ' +
response.getStatusCode() + ' ' + response.getStatus());
} else {
System.debug(response.getBody());
}
´´´´

Answer 1

Have you added the remote site? It is the probable reason I believe.
If not, try
From Setup, enter Remote Site Settings in the Quick Find box, then
select Remote Site Settings.
Click New Remote Site.
Enter a descriptive term for the Remote Site Name.
Enter the URL for
the remote site. Optionally, enter a description of the site.
Click Save