// Start the authorization process
func (this *FacebookController) Auth(ctx framework.WebContext) framework.WebResult {
//can be used to pass state between server-to-server calls (roundtripped)
state := ""
//Get the Google URL which shows the Authentication page to the user
url := this.oauthCfg.AuthCodeURL(state)
//redirect user to that page
return ctx.Redirect(url)
}