简单分页

步骤：

1. 参数: 第几页，每页多少条数据，前端get方式传递数据
2. 后台接收参数并获取数据，同时返回表记录总条数，用于判断最后一页

代码1：

// 获取音乐列表-controllers
    public function getMusicList($page, $num)
    {
        $data = $this->AlbumMusic_model->get($page, $num);
        $this->output->set_content_type('application/json')->set_output(json_encode($data));
    }
// 获取音乐列表-models
    public function get($page, $num)
    {
        $data = array(
            'count' => $this->db->count_all('album_music'),
            'data' => $this->db->get('album_music', $num, ($page-1)*$num)->result()
        );
        return $data;
    }

代码2：

  loadMusic (page, num) {
    let that = this
    // 获取音乐歌曲列表
    wx.request({
      url: app.globalData.host + '/album/getMusicList/' + page + '/' + num,
      success: res => {
        let musicList = res.data.data
        that.data.count = res.data.count
        // 添加设置
        let music = wx.getStorageSync('music')
        for (let i = 0; i < musicList.length; i++) {
          musicList[i].play = false
          musicList[i].select = false
          if (musicList[i].id == music.id) {
            musicList[i].select = true
          }
        }
        that.setData({
          musicList: musicList
        })
      }
    })
  },
  beforeBtn (e) {
    this.data.page--
    if(this.data.page < 1) {
      wx.showToast({
        title: '已经是第一页了',
        icon: 'success',
        duration: 2000
      })
      this.data.page = 1
      return
    }
    this.loadMusic(this.data.page, this.data.num_page)
  },
  afterBtn (e) {
    this.data.page++
    // console.log(this.data.page)
    if (this.data.page > Math.ceil(this.data.count / this.data.num_page)){
      wx.showToast({
        title: '没有更多音乐了',
        icon: 'success',
        duration: 2000
      })
      this.data.page = Math.ceil(this.data.count / this.data.num_page)
      return
    }
    this.loadMusic(this.data.page, this.data.num_page)
  }