getOpenIdData: function(cb) {
  var that = this
  //调用登录接口
  wx.login({
    success: function(res) {
      wx.request({
        url: 'https://api.weixin.qq.com/sns/jscode2session',
        data: {
          appid: "wx6224eb*********",
          secret: "879b58fc64bc5**************",
          js_code: res.code,
          grant_type: "authorization_code"
        },
        success: function(res) {
          // 保存到全局变量中
          that.globalData.openid = res["data"]["openid"]
          cb(that.globalData.openid)
        },
        fail: function() {
          console.log("request error")
        }
      })
    }
  })
}

var app = getApp()
app.getOpenIdData(function(openid){
  //回调更新数据
  that.setData({
  openid: openid
  })
})

function(openid){
  //回调更新数据
  that.setData({
  openid: openid
  })
}