diff --git a/README.md b/README.md
index 3243a8e..2bec95d 100644
--- a/README.md
+++ b/README.md
@@ -36,13 +36,15 @@ Create `config/initializers/wx_pay.rb` and put following configurations into it.
 WxPay.appid = 'YOUR_APPID'
 WxPay.key = 'YOUR_KEY'
 WxPay.mch_id = 'YOUR_MCH_ID'
-WxPay.appsecret = 'YOUR_SECREDT'
 WxPay.debug_mode = true # default is `true`
 
 # cert, see https://pay.weixin.qq.com/wiki/doc/api/app/app.php?chapter=4_3
 # using PCKS12
 WxPay.set_apiclient_by_pkcs12(File.read(pkcs12_filepath), pass)
 
+# if you want to use `generate_authorize_req` and `authenticate`
+WxPay.appsecret = 'YOUR_SECRET' 
+
 # optional - configurations for RestClient timeout, etc.
 WxPay.extra_rest_client_options = {timeout: 2, open_timeout: 3}
 ```
@@ -89,13 +91,9 @@ r = WxPay::Service.invoke_unifiedorder params
 #    }
 ```
 
-"JSAPI" requires openid in params, authenticate_openid can be used to get it, in case there is not wechat auth integration.
-
-```ruby
-code = params[:code]
-r = WxPay::Service.authenticate_openid code
-# => 'OPENID'
-```
+> "JSAPI" requires openid in params,
+in most cases I suggest you using [omniauth](https://github.com/omniauth/omniauth) with [omniauth-wechat-oauth2](https://github.com/skinnyworm/omniauth-wechat-oauth2) to resolve this,
+but `wx_pay` provides `generate_authorize_url` and `authenticate` to help you get Wechat authorization in simple case.
 
 If your trade type is "NATIVE", the result would be like this.
 
@@ -188,7 +186,7 @@ def notify
 end
 ```
 
-### Integretion with QRCode(二维码)
+### Integrate with QRCode(二维码)
 
 Wechat payment integrating with QRCode is a recommended process flow which will bring users comfortable experience. It is recommended to generate QRCode using `rqrcode` and `rqrcode_png`.
 
diff --git a/lib/wx_pay/service.rb b/lib/wx_pay/service.rb
index a95a68a..c963200 100644
--- a/lib/wx_pay/service.rb
+++ b/lib/wx_pay/service.rb
@@ -1,35 +1,27 @@
 require 'rest_client'
 require 'json'
-require 'rails'
+require 'securerandom'
 require 'active_support/core_ext/hash/conversions'
 
 module WxPay
   module Service
     GATEWAY_URL = 'https://api.mch.weixin.qq.com'
 
-    def self.authenticate_openid(code)
-      """
-        Acquire openid from wechat server.
-        When trade type is JSAPI, openid is required in params to do unifiedorder.
-        If application does not integrate wechat auth plugin, this function can be used to get openid.
-        Wechat doc for explaining acquire openid: http://mp.weixin.qq.com/wiki/17/c0f37d5704f0b64713d5d2c37b468d75.html
-
-        params:
-          code, the code return by wechat server after user authentification
-        return:
-          openid
-      """
-      # step 1. Redirect to wechat server to get code. If code exits, it can be skiped.
-      if code.nil?
-        redirect_to "https://open.weixin.qq.com/connect/oauth2/authorize?appid=#{WxPay.appid}&redirect_uri=#{request.url}&response_type=code&scope=snsapi_base&state=#{request.url}#wechat_redirect"
-      end
+    def self.generate_authorize_url(redirect_uri, state = nil)
+      state ||= SecureRandom.hex 16
+      "https://open.weixin.qq.com/connect/oauth2/authorize?appid=#{WxPay.appid}&redirect_uri=#{redirect_uri}&response_type=code&scope=snsapi_base&state=#{state}"
+    end
 
-      # step 2. Get Auth Info and openid from wechat server with code
-      begin
-        url    = "https://api.weixin.qq.com/sns/oauth2/access_token?appid=#{WxPay.appid}&secret=#{WxPay.appsecret}&code=#{code}&grant_type=authorization_code"
-        weixin_openid = JSON.parse(URI.parse(url).read)["openid"]
-      end
-      weixin_openid
+    def self.authenticate(authorization_code, options = {})
+      options = WxPay.extra_rest_client_options.merge(options)
+      url = "https://api.weixin.qq.com/sns/oauth2/access_token?appid=#{WxPay.appid}&secret=#{WxPay.appsecret}&code=#{authorization_code}&grant_type=authorization_code"
+
+      ::JSON.parse(RestClient::Request.execute(
+        {
+          method: :get,
+          url: url
+        }.merge(options)
+      ), quirks_mode: true)
     end
 
     INVOKE_UNIFIEDORDER_REQUIRED_FIELDS = [:body, :out_trade_no, :total_fee, :spbill_create_ip, :notify_url, :trade_type]
@@ -220,9 +212,9 @@ module WxPay
         nonce_str: SecureRandom.uuid.tr('-', '')
       }.merge(params)
 
-      check_required_options(params, ORDER_QUERY_REQUIRED_FIELDS)
 
       r = WxPay::Result.new(Hash.from_xml(invoke_remote("#{GATEWAY_URL}/pay/orderquery", make_payload(params), options)))
+      check_required_options(params, ORDER_QUERY_REQUIRED_FIELDS)
 
       yield r if block_given?
 
@@ -294,7 +286,7 @@ module WxPay
       private
 
       def check_required_options(options, names)
-        return if !WxPay.debug_mode?
+        return unless WxPay.debug_mode?
         names.each do |name|
           warn("WxPay Warn: missing required option: #{name}") unless options.has_key?(name)
         end
--
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