小程序云开发用云函数获取sessionkey和opengid-即速应用

目前小程序获取群ID只有一个办法，就是分享小程序到微信群后，用户从微信点小程序进来，才能获取群ID。

测试页面test.wxml

<view>  <view wx:if="{{openGid}}" class='groupName'>    群名称：    <open-data type="groupName" open-gid="{{openGid}}"></open-data>  </view>  <view wx:else>    <button class='button' bindtap='clickReload'>点击加载群名称和群ID</button>  </view>  <view class='button'>{{openGid ? openGid : ' '}}</view>  <view>把这个页面在真机上分享到微信群，然后从群里点进来，再点击按钮就能获取群ID</view></view>

test.js

const app = getApp()Page({  /**   * 页面的初始数据   */  data: {  }, onLoad: function (options) {    let that = this    wx.showShareMenu({//设为true，获取ShareTicket      withShareTicket: true    })    app.getShareTiket(function (globalData) {      console.log('clickReload---globalData-->' + JSON.stringify(globalData))      that.setData({        openGid: globalData.openGid      })    })  },  clickReload: function () {    let that = this    app.getShareTiket(function (globalData) {      console.log('clickReload---globalData-->' + JSON.stringify(globalData))      that.setData({        openGid: globalData.openGid      })    })  }})

app.js

wx.cloud.init();App({ onShow: function (options) {    let that = this    if (options && options.scene == 1044) {      //获取shareTicket      that.globalData.shareTicket = options.shareTicket    }    console.log('onShow---options=--->' + JSON.stringify(options))  },  getShareTiket: function (cb) {    let that = this    if (that.globalData.shareTicket) {      wx.getShareInfo({        shareTicket: that.globalData.shareTicket,        success: function (res) {          console.log('getShareTiket---shareTicket-->' + JSON.stringify(res))          //获取encryptedData、iv          let js_encryptedData = res.encryptedData          let js_iv = res.iv          wx.login({            success: function (res) {              //获取code              console.log('code-->' + res.code)                           //调用云函数，破解opengid              wx.cloud.callFunction({                name: 'opengid',                data: {                  js_code: res.code,                  appId: 'wx7c1126bc182ab756',                  encryptedData: js_encryptedData,                  iv: js_iv                },                success: function (res) {                  console.log('打印opengid' + res.result.openGId);                                  console.log('res' + JSON.stringify(res));                  that.globalData.openGid = res.result.openGId                  console.log('getShareTiket---openGid' + that.globalData.openGid)                  typeof cb == "function" && cb(that.globalData)                },                fail: function (err) {                  console.log('getShareTiket---err' + JSON.stringify(err))                }                           })            }          })        }      })    } else {      console.log('不存在shareTicket')    }  },  globalData: {    shareTicket: '',    openGid: ''   }})

在云函数couldfunctions目录下新建opengid云函数，在opengid目录下用npm安装crypto和request。

opengid/index.js

const cloud = require('wx-server-sdk');const WXBizDataCrypt = require('./WXBizDataCrypt')const requestSync = require('./requestSync')cloud.init();/*传入参数{  data:{    js_code,    encryptedData,    iv  }}*/exports.main = async (event, context) => {  const code = event.js_code;  const appid = event.userInfo.appId;  const encryptedData = event.encryptedData;  const iv = event.iv;  const secret = '填你小程序的secret'  const url = {    url: 'https://api.weixin.qq.com/sns/jscode2session?appid=' + appid + '&secret=' + secret + '&js_code=' + code + '&grant_type=authorization_code'  }  const req = await requestSync(url);  const session = JSON.parse(req);  const sessionKey = session.session_key;  const pc = new WXBizDataCrypt(appid, sessionKey);  const data = pc.decryptData(encryptedData, iv);  return data;}

另外在opengid目录下新建requestSync.js,获取sessionKey

const request = require("request");const requestSync = async (url) =>  new Promise((resolve, reject) => {    request(url, (err, response, body) => {      if (err) {        reject(err);      } else {        resolve(body);      }    })  })module.exports = requestSync

在opengid目录下新建WXBizDataCrypt.js,用来解密,这段代码是微信官网示例代码nodejs版本。

var crypto = require('crypto')function WXBizDataCrypt(appId, sessionKey) {  this.appId = appId  this.sessionKey = sessionKey}WXBizDataCrypt.prototype.decryptData = function (encryptedData, iv) {  // base64 decode  var sessionKey = new Buffer(this.sessionKey, 'base64')  encryptedData = new Buffer(encryptedData, 'base64')  iv = new Buffer(iv, 'base64')  try {    // 解密    var decipher = crypto.createDecipheriv('aes-128-cbc', sessionKey, iv)    // 设置自动 padding 为 true，删除填充补位    decipher.setAutoPadding(true)    var decoded = decipher.update(encryptedData, 'binary', 'utf8')    decoded += decipher.final('utf8')    decoded = JSON.parse(decoded)  } catch (err) {    console.log('try err', err)    throw new Error('Illegal Buffer1')  }  if (decoded.watermark.appid !== this.appId) {    throw new Error('appid unmatch')  }  return decoded}module.exports = WXBizDataCrypt

在模拟器上无法获取shareTicket，你要在真机上建一个群，然后分享点击，才能获取shareTicket，进而解出opengid。

代码没有完全调试，直接复制粘贴，可能会报错，如果报错，请留言告知。

整体上看用云函数和原来的服务端开发差不多，熟悉了感觉更方便，毕竟不需要搭建后端了。如果后期微信能像获取openid一样方便的获取群ID那就更好了。现在的过程还是太绕了。

感谢这两位朋友提供的代码，是他们提供轮子。
小程序如何获取群聊的openGid以及名称
小程序用云函数获取opengid

调试过程遇到的坑。

对象不能直接打印出来，需要用JSON.stringify()转成json才能打印出来。