微信登录授权

微信小程序的登录授权一是只通过微信小程序的开发文档上授权，但是这种授权方式无法获取openid只是快捷展示信息，

需要对数据库和用户信息操作则需要依照微信开放平台上先访问接口获取code，然后在拿到code去访问后端的接口
后端携带code去访问微信api，之后把信息返回给前端，文档地址：https://developers.weixin.qq.com/doc/oplatform/Mobile_App/WeChat_Login/Authorized_API_call_UnionID.html

var openId = (wx.getStorageSync('openId'))
        if (openId) {
          wx.getUserInfo({
            success: function (res) {
              that.setData({
                nickName: res.userInfo.nickName,
                avatarUrl: res.userInfo.avatarUrl,
              })
            },
            fail: function () {
              // fail
              console.log("获取失败！")
            },
            complete: function () {
              // complete
              console.log("获取用户信息完成！")
            }
          })
        } else {
          wx.login({
            success: function (res) {
              console.log(res.code)
              if (res.code) {
                wx.getUserInfo({
                  withCredentials: true,
                  success: function (res_user) {
                    wx.request({
                     //后台接口地址
                      url: 'https://....com/wx/login',
                      data: {
                        code: res.code,
                        encryptedData: res_user.encryptedData,
                        iv: res_user.iv
                      },
                      method: 'GET',
                      header: {
                        'content-type': 'application/json'
                      },
                      success: function (res) {
                        // this.globalData.userInfo = JSON.parse(res.data);
                        that.setData({
                          nickName: res.data.nickName,
                          avatarUrl: res.data.avatarUrl,
                        })
                        wx.setStorageSync('openId', res.data.openId);

                      }
                    })
                  }, fail: function () {
                    wx.showModal({
                      title: '警告通知',
                      content: '您点击了拒绝授权,将无法正常显示个人信息,点击确定重新获取授权。',
                      success: function (res) {
                        if (res.confirm) {
                          wx.openSetting({
                            success: (res) => {
                              if (res.authSetting["scope.userInfo"]) {////如果用户重新同意了授权登录
                                wx.login({
                                  success: function (res_login) {
                                    if (res_login.code) {
                                      wx.getUserInfo({
                                        withCredentials: true,
                                        success: function (res_user) {
                                          wx.request({
                                           url: 'https://....com/wx/login',
                                            data: {
                                              code: res_login.code,
                                              encryptedData: res_user.encryptedData,
                                              iv: res_user.iv
                                            },
                                            method: 'GET',
                                            header: {
                                              'content-type': 'application/json'
                                            },
                                            success: function (res) {
                                              that.setData({
                                                nickName: res.data.nickName,
                                                avatarUrl: res.data.avatarUrl,

                                              })
                                              wx.setStorageSync('openId', res.data.openId);
                                            }
                                          })
                                        }
                                      })
                                    }
                                  }
                                });
                              }
                            }, fail: function (res) {

                            }
                          })

                        }
                      }
                    })
                  }, complete: function (res) {


                  }
                })
              }
            }
          })

        }


  },
  globalData: {   
    userInfo: null
  }