Wechat : Login the user, get the openId, getUserInfo

getOpenid-wechat-login.js

/**
* We login the user to our mini-program
* We get the user Info (the user info don't contain the unionId)
* We make a request to our back-end to request the unionId.
* * For security reason wechat doesn't allow us to make that request on the front-end : https://api.weixin.qq.com/sns/jscode2session?appid=${process.env.APP_ID}&secret=${process.env.APP_SECRET}&js_code=${js_code} 
* * To make that request we need(see at the bottom) : {secret,appId, js_code(login code)}

/** Client-Side **/
import http from '../utils/http.js'

/**
 * @description Handle the login to wechat
 * https://developers.weixin.qq.com/miniprogram/dev/api/open-api/user-info/wx.getUserInfo.html
 * @returns {Promise} Return the user's wechat information.
 * {"openId", "nickName","gender", "city", "province", "country", "avatarUrl" }
 */
export function handleWxLogin() {
  return new Promise((resolve, reject) => {
     wx.login({
        success : async function (res) {
          const js_code = res.code;
          const userInfo =  getUserInfo()
          const openID = getOpenID(js_code)
          const payload = {
            ...await userInfo,
            ...{openID:await openID}
          }
          console.info('handleWxLogin payload:', payload);
          resolve(payload)
        },
        fail: function(err){
          console.log('wx.login error:',err);
          reject(err)
           }
        })
    })
}

/**
 * @description GET request to get the OpenID from the server.
 * @param {String} js_code
 * @returns {Promise} Return openID
 */
async function getOpenID(js_code){
  // A GET request to our back-end.
 return http.get(`wxUnionID?js_code=${js_code}`).then(res => {
    if(res){
      return res.data.openid;
    }
  }).catch(err => {
    console.warn('getOpenID error:',err,);
  })
}

/**
 * @description Get the userInfo with wx.getUserInfo
 * https://developers.weixin.qq.com/miniprogram/dev/api/open-api/user-info/wx.getUserInfo.html
 * @returns {Promise} returns an object
 */
function getUserInfo(){
  return new Promise((resolve, reject) => {
    wx.getUserInfo({
      success: async function(res) {
        const userInfo = res.userInfo;
        resolve(userInfo)
      },
      fail: function(err){
        console.warn('getUserInfo error:',err,);
        reject('getUserInfo error:',err)
      }
    })
  })
}


/** BACKEND Side **/

const bent = require("bent");
/**
 * @description We get the openid from weixin.
 * https://developers.weixin.qq.com/miniprogram/en/dev/api-backend/open-api/login/auth.code2Session.html
 * @param {String} js_code (the code provided during the login)
 * APP_ID and APP_SECRET can be found on the developper dashboard.
 * @returns {Promise} {session_key, openid}
 */
module.exports = {
  wxUnionID: async ctx => {
    const query = ctx.request.query;
    const js_code = query.js_code;
    const getJSON = bent("json");
    const user = await getJSON(
      `https://api.weixin.qq.com/sns/jscode2session?appid=${process.env.APP_ID}&secret=${process.env.APP_SECRET}&js_code=${js_code}`
    );
    console.info('user:', user)
    if(user.openid){
      ctx.send({
        statusCode: 200,
        error: null,
        data:user,
      });
    }else{
      ctx.send({
        statusCode: 400,
        error: user,
        data:null,
      });
    }
  }
};