weapp: fix api

app/controllers/weapps/code_sessions_controller.rb

@@ -5,16 +5,23 @@ class Weapps::CodeSessionsController < Weapps::BaseController
 
     result = Wechat::Weapp.jscode2session(params[:code])
 
-    # 已授权，绑定过账号
+    # 能根据 code 拿到 unionid
     open_user = OpenUsers::Wechat.find_by(uid: result['unionid'])
     if open_user.present? && open_user.user
       successful_authentication(open_user.user)
       set_session_unionid(result['unionid'])
       logged = true
     else
-      # 新用户
+      # 根据 code没拿到 unionid
       user_info = Wechat::Weapp.decrypt(result['session_key'], params[:encrypted_data], params[:iv])
 
+      # 老用户，已绑定
+      open_user = OpenUsers::Wechat.find_by(uid: user_info['unionid'])
+      if open_user.present? && open_user.user
+        successful_authentication(open_user.user)
+        logged = true
+      end
+
       set_session_unionid(user_info['unionId'])
     end
 
@@ -22,5 +29,7 @@ class Weapps::CodeSessionsController < Weapps::BaseController
     set_weapp_session_key(result['session_key']) # weapp session_key写入缓存 后续解密需要
 
     render_ok(openid: result['openid'], logged: logged)
+  rescue Wechat::Error => ex
+    render_error(ex.message)
   end
 end

app/libs/wechat/weapp.rb

@@ -34,7 +34,7 @@ class Wechat::Weapp
       data = cipher.update(encrypted_data) << cipher.final
       result = JSON.parse(data[0...-data.last.ord])
 
-      raise Wechat::Error, '解密错误' if result.dig('watermark', 'appid') != appid
+      raise Wechat::Error.new(-1, '解密错误') if result.dig('watermark', 'appid') != appid
       result
     end