PreRequest Script for Postman to get an access token for a resouce using the client credentials flow

Postman_GetAccessToken_PreRequestScript

var client_id      = pm.environment.get("client_id");
var client_sercret = pm.environment.get("client_secret");
var token_endpoint = pm.environment.get("token_endpoint");
var scope          = pm.environment.get("scope");

pm.sendRequest({
    url: token_endpoint,
    method: 'POST',
    header: {
        'Content-Type': 'multipart/form-data',
          },
      body: {
          mode: 'formdata',
          formdata: [
            {key: "grant_type"    , value: "client_credentials"}, 
            {key: "client_id"     , value: client_id},
            {key: "client_secret" , value: client_sercret},
            {key: "scope"         , value: scope}      
        ]
      }
},  function(err, response) {
  const jsonResponse = response.json();
  
  console.log(jsonResponse);

  pm.environment.set("access_token", jsonResponse.access_token);
  console.log(pm.environment.get("access_token"));

});