wechat gem是一个很优秀的gem, 使用这个gem使rails开发者可以迅速的接入微信服务号/订阅号。

我这里遇到一个需求，是网站需要支持多个服务号，经过一系列研究,觉得还是后期的hack做法比较简单，现分享此方法。

• 创建一个Model，WechatApp，此model需要包含原有wechat.yml中的属性。

• 在initializers中加入wechat.rb，内容如下

module Wechat
  def self.config(account = :default)
    if account == :default
      Wechat::ApiLoader.config(account)
    else
      app = WechatApp.find account.to_s
      value = { appid: app.appid,
        secret: app.secret,
        corpid: nil,
        corpsecret: nil,
        agentid: nil,
        token: app.token,
        access_token: app.access_token,
        encrypt_mode: app.encrypt_mode,
        timeout: 120,
        skip_verify_ssl: app.skip_verify_ssl,
        encoding_aes_key: app.encoding_aes_key,
        jsapi_ticket: app.jsapi_ticket,
        trusted_domain_fullname: app.trusted_domain_fullname }
      OpenStruct.new value
    end
  end

  def self.api(account = :default)
    @wechat_apis ||= {}
    if account == :default
      @wechat_apis[account.to_sym] ||= Wechat::ApiLoader.with(account: account)
    else
      @wechat_apis[account.to_sym] ||= Helper.new.send(:load_controller_wechat, account)
    end
  end

  class Helper
    include ActionController::WechatResponder

    attr_accessor :wechat_api_client, :wechat_cfg_account, :token, :appid, :corpid, :agentid, :encrypt_mode, :timeout,
                    :skip_verify_ssl, :encoding_aes_key, :trusted_domain_fullname, :oauth2_cookie_duration
  end
end

• 在controller中加一个concern, 我这里叫Wechat::Hack

module Wechat::Hack
  extend ActiveSupport::Concern

  included do
    before_action :set_wechat_client
  end

  def set_wechat_client
    appid = params[:appid] || session[:appid]
    if appid.to_s.size > 0
      app = WechatApp.find appid
      @app = app
      session[:account] = app.id.to_s.to_sym
      Thread.current[:account] = app.id.to_s.to_sym
    end

  end

  module ClassMethods
    def appid
      Wechat.config(Thread.current[:account] || :default).appid
    end
    ###
        #此处 省略几十行
        ###
  end
end

• 在responses_controller中引入此gem

class Wechat::ResponsesController < ActionController::Base
  wechat_responder

  include Wechat::Hack
end

以subscribe 为例

  on :event, with: "subscribe" do |request, e|
    wechat_user = wechat.user request[:FromUserName]
    wechat_app = WechatApp.find session[:account].to_s

        welcome_text = get_text_from_wechat_app(wechat_app)
    request.reply.text(welcome_text)
  end

WechatApi的接入与此类似，但需要更多几个方法hack.