public static AccessToken GetAccessToken(WeChatPayConfig config, string code) { if (string.IsNullOrEmpty(code)) { throw new Exception("Authentication code must be provided"); } AccessToken token = null; AuthAccessTokenRequest authRequest = new AuthAccessTokenRequest(config); authRequest.code = code; BaseResponse res = authRequest.Execute(); if (res != null) { token = ((AccessTokenResponse)res).Access_Token; } return(token); }