Wechat

Wechat API wrapper in Elixir.

Installation

1. Add wechat to your list of dependencies in mix.exs:

   def deps do
     [{:wechat, "~> 0.1.0"}]
   end

2. Dont start wechat in mix file

3. Start a GenServer (Or start multiple with different account info) with the offical account info:

   wechat_config_data = %Wechat.ConfigData{appid: my_official_appid,
                                           secret: my_official_secret,
                                           token_file: "/choose/a/temp/location/"} #Default is /tmp/access_token
   Wechat.start(:my_genserver, wechat_config_data)

Config

• Add config in config.exs

  config :wechat, Wechat,
    token: "wechat token",
    encoding_aes_key: "32bits key"

Usage

• send_text_message

  Wechat.send_text_message(:my_genserver, open_id, text)

Plug

• Wechat.Plugs.CheckUrlSignature

  • Check url signature
  • 接入指南

• Wechat.Plugs.CheckMsgSignature

  • Parse xml message (support decrypt msg)
  • 消息加密解密技术方案

Plug Usage (in Phonenix controller)

• router.ex

  defmodule MyApp.Router do
    pipeline :api do
      plug :accepts, ["json"]
    end
  
    scope "/wechat", MyApp do
      pipe_through :api
  
      # validate wechat server config
      get "/", WechatController, :index
  
      # receive wechat push message
      post "/", WechatController, :create
    end
  end

• wechat_controller.ex

  defmodule MyApp.WechatController do
    use MyApp.Web, :controller
  
    plug Wechat.Plugs.CheckUrlSignature
    plug Wechat.Plugs.CheckMsgSignature when action in [:create]
  
    def index(conn, %{"echostr" => echostr}) do
      text conn, echostr
    end
  
    def create(conn, _params) do
      msg = conn.assigns[:msg]
      reply = build_text_reply(msg, msg.content)
      render conn, "text.xml", reply: reply
    end
  
    defp build_text_reply(%{tousername: to, fromusername: from}, content) do
      %{from: to, to: from, content: content}
    end
  end

• text.xml.eex

  <xml>
    <MsgType><![CDATA[text]]></MsgType>
    <Content><![CDATA[<%= @reply.content %>]]></Content>
    <ToUserName><![CDATA[<%= @reply.to %>]]></ToUserName>
    <FromUserName><![CDATA[<%= @reply.from %>]]></FromUserName>
    <CreateTime><%= DateTime.to_unix(DateTime.utc_now) %></CreateTime>
  </xml>