微信扫码登录。

README.md

1. 判定是否在微信中打开

def wechat?
    request.user_agent =~ /MicroMessenger/i 
end

2. 分别调用 微信网页扫码 或 公众号授权

def wechat_cli
    @wechat_cli ||= if wechat?
       WechatMp.new('key', 'secret') # 微信公众号
    else
       Wechat.new('key', 'secret') # 微信扫码
    end 
end

3. 跳转页

redirect wechat_cli.authorize_uri, permanent: true

3. 回调处理

unauthorized('未获得授权') if params[:code].blank?
token = wechat_cli.token(params[:code]) 
if token && token['unionid']
    # 通过 token['unionid'] 查询是否已存在
    # 通过 wechat_cli.userinfo(token) 获取用户信息
end

rest_cli.rb

# -*- encoding: utf-8 -*-

class RestCli
  def initialize(endpoint)
    connection.url_prefix = endpoint
  end

  def get(path, params=nil, headers = nil)
    self.request(:get, path, params, headers)
  end

  def post(path, params=nil, headers = nil)
    self.request(:post, path, params, headers)
  end

  def request(method, url, body, headers=nil)
    parser connection.send(method, url, body, headers)
  rescue Faraday::TimeoutError, Faraday::ConnectionFailed => e
    puts '_'*88
  end
  
  def connection
    @connection ||= Faraday.new( ssl: { verify: false } ) do |conn|
      conn.request  :multipart
      conn.request  :url_encoded
      conn.request  :retry, max: 2, interval: 0.05,
                    interval_randomness: 0.5, backoff_factor: 2,
                    exceptions: [Faraday::TimeoutError, Timeout::Error]
      conn.response :logger
      conn.adapter  :typhoeus
      conn.options.open_timeout = 10
      conn.options.timeout = 10
    end
  end

  def parser(resp)
    MultiJson.load(resp.body) rescue nil if resp.status.between?(200,201)
  end
end

wechat.rb

# -*- encoding: utf-8 -*-

class Wechat < RestCli # 微信网页扫码
  def initialize(key, secret, endpoint='https://api.weixin.qq.com')
    @params = {
      appid: key,
      secret: secret
    }

    connection.url_prefix = endpoint
  end

  def token(code)
    resp = get('/sns/oauth2/access_token', @params.merge(code: code, grant_type: 'authorization_code'))
    resp.as_json(only: ['unionid', 'access_token', 'openid'])
  end

  def userinfo(params)
    info = {}
    resp = get('/sns/userinfo', params)
    if resp && resp['nickname']
      info = resp.as_json(only: ['nickname', 'headimgurl'])
      info = {
        username: info['nickname'], 
        avatar_url: (info['headimgurl'] + '/avatar.jpg'),
        role: :user
      }
    end
    info
  end

  def authorize_uri
    'https://open.weixin.qq.com/connect/qrconnect?' + query_string + '#wechat_redirect'
  end

  private

    def query_string
      {
        appid:         @params[:appid],
        redirect_uri:  '回调URL',
        response_type: 'code',
        scope:         'snsapi_login',
        state:         'qrconnect'
      }.to_query
    end
end

wechat_mp.rb

# -*- encoding: utf-8 -*-

class WechatMp < Wechat # 微信公众号

  def authorize_uri
    'https://open.weixin.qq.com/connect/oauth2/authorize?' + query_string + '#wechat_redirect'
  end

  private

    def query_string
      {
        appid:         @params[:appid],
        redirect_uri:  '回调URL',
        response_type: 'code',
        scope:         'snsapi_userinfo',
        state:         'oauth2'
      }.to_query
    end
end