Get Refresh Token using the Postman Pre-Request Script

Get Refresh Token using the Postman Pre-Request Script.js

if(pm.response.code === 200 || pm.response.code === 201){
    var responseBody = pm.response.json();
    
    pm.environment.set('access_token', responseBody.access_token);
    pm.environment.set('refresh_token', responseBody.refresh_token);
    pm.environment.set('scope', responseBody.scope);
    pm.environment.set('id_token', responseBody.id_token);
    pm.environment.set('instance_url', responseBody.instance_url);
    pm.environment.set('token_type', responseBody.token_type);

    pm.environment.set('token_created_at', ( new Date() ).getTime() );
    var expiryDate = new Date();
    expiryDate.setSeconds(expiryDate.getSeconds() + 3600*2);
    
    pm.environment.set('token_expires_at', expiryDate.getTime() );
}

refresh_token.js

const refreshTokenRequest = {
  url: pm.collectionVariables.get('token_endpoint'),
  method: 'POST',
  header: {
    'Content-Type': 'application/x-www-form-urlencoded',
  },
  body: {
        mode: 'urlencoded',
        urlencoded: [
                { key: "client_id", value: pm.environment.get('client_id') },
                { key: "client_secret", value: pm.environment.get('client_secret') },
                { key: "refresh_token", value: pm.environment.get('refresh_token') },
                { key: "grant_type", value: "refresh_token" },
        ]
    }
};

var getToken = true;

if ( !pm.environment.get('token_expires_at') ) {
    console.log('Token or expiry date are missing');
} else if (pm.environment.get('token_expires_at') <= (new Date()).getTime()) {
    console.log('Token is expired')
} else {
    getToken = false;
    console.log('Token and expiry date are all good');
    console.log('Setting the Access token at header level ...');
    pm.request.headers.add({
        key: "Authorization",
        value: "Bearer "+pm.environment.get('access_token')
    });
}

if (getToken === true) {
    pm.sendRequest(refreshTokenRequest, function (err, res) {
        var responseJson = res.json();
        if (err === null && responseJson.access_token) {
            console.log('Saving the token and expiry date from refresh token API Call')
            console.log( responseJson );
            pm.environment.set('access_token', responseJson.access_token)
    
            var expiryDate = new Date();
            expiryDate.setSeconds(expiryDate.getSeconds() + 3600*2 );
            pm.environment.set('token_expires_at', expiryDate.getTime());
            console.log('Setting the Access token at header level ...');
            pm.request.headers.add({
                key: "Authorization",
                value: "Bearer "+pm.environment.get('access_token')
            });
        }else{
            console.log('Error while getting the refresh token ');
            console.log( responseJson );
        }
    });
}