本Rails Engine是为了方便公众号运维人员统一管理公众号的开发接口，不同公众号由同一个Rails管理和驱动，对不同的公众号，可实现如下功能：
- 修改自定义菜单
- 实现网页授权登录，获取用户信息并保存在数据库
- 接收微信服务器推送信息，实现自动回复和其他高级功能
Gemfile:
gem 'weixin_pem'
config/routes:
mount WeixinPam::Engine => '/'
启动Rails server
bundle exec rails s
访问：http://localhost:3000/public_accounts 即可添加／删除公众号配置
点击已添加的公众号名字，点击“微信菜单”按钮，该页面可实现如下功能
- 下载公众号菜单
- 上传公众号菜单
- 添加菜单到数据库
- 移动菜单到“未启用的列表”
- 对菜单排序
本例子使用Devise作为用户登录模块，用到gem omniauth-wechat-oauth2
Gemfile中：
gem 'devise'
gem "omniauth-wechat-oauth2"
config/initializers/devise.rb
require 'omniauth_setup'
# 此处 setup: OmniauthSetup是关键，他实现不同公众号的api身份切换
config.omniauth :wechat, nil, nil, setup: OmniauthSetup
lib/omniauth_setup.rb
class OmniauthSetup
# OmniAuth expects the class passed to setup to respond to the #call method.
# env - Rack environment
def self.call(env)
new(env).setup
end
# Assign variables and create a request object for use later.
# env - Rack environment
def initialize(env)
@env = env
@request = ActionDispatch::Request.new(env)
end
# The main purpose of this method is to set the consumer key and secret.
def setup
@env['omniauth.strategy'].options.merge!(custom_credentials)
puts
puts @env['omniauth.strategy'].options.inspect
puts
end
private
# Use the subdomain in the request to find the account with credentials
def custom_credentials
h = {}
scope = @request.params.delete(:scope).presence
h[:scope] = scope if scope
if account = WeixinPam::PublicAccount.find_by(host: @request.host)
h.update client_id: account.app_id, client_secret: account.app_secret
end
h
end
end
config/routes.rb
devise_for :users, :controllers => { :omniauth_callbacks => "users/omniauth_callbacks" }
app/controllers/users/omniauth_callbacks_controller.rb
class Users::OmniauthCallbacksController < Devise::OmniauthCallbacksController
def wechat
public_account = WeixinPam::PublicAccount.find_by!(host: request.host)
ua = WeixinPam::UserAccount.from_omniauth(public_account, request.env["omniauth.auth"])
if ua.user.persisted?
update_stored_location_url ua.user
sign_in_and_redirect ua.user, :event => :authentication
set_flash_message(:notice, :success, :kind => '微信') if is_navigational_format?
else
session["devise.wechat_data"] = request.env["omniauth.auth"]
redirect_to new_user_registration_url
end
end
private
def update_stored_location_url(user)
if url = request.env['omniauth.params']['redirect'] || request.env['omniauth.origin']
store_location_for user, url
end
end
end
创建的公众号如果不填写"微信服务器事件推送的响应Class",WeixinPam会使用开发模式下的默认值PublicAccountReply（lib/public_account_reply.rb）
针对不同公众号，我们可以编写不同的Reply Class去继承PublicAccountReply,实现不同公众号有不同的回复内容。
添加config/initializers/weixin_pam.rb,加入如下代码
WeixinPam::ApplicationController.class_eval do
before_action :authenticate_user!
before_action :ensure_admin_user
private
def ensure_admin_user
fail "没有访问权限" unless current_user.admin?
end
end