PHP implementation of pull-down refresh and loading more functional techniques in WeChat applet

With the popularity of WeChat mini programs, more and more developers are beginning to use PHP as the back-end language to implement data interaction and processing in mini programs. In the development of mini programs, pull-down refresh and loading more functions are very common requirements. Today I will introduce the techniques of using PHP to implement pull-down refresh and load more functions in WeChat mini programs.

1. Pull-down refresh

Pull-down refresh is a common way to display list data. Users can get the latest data through the drop-down list. In the WeChat applet, we can use the onPullDownRefresh life cycle function provided by the applet to implement the pull-down refresh function. On this basis, we can use PHP to obtain the latest data.

1. Front-end implementation

Add the onPullDownRefresh listening function in the js file of the mini program page, and call the back-end interface to obtain the latest data.

Page({
  data: {
    listData: []
  },
  onPullDownRefresh: function () {
    var that=this;
    wx.request({
      url: 'http://yourdomain.com/api/getdata.php',   //后端接口地址
      data: {
        pageNo:1    //请求第一页的数据
      },
      success: function (res) {
        that.setData({
          listData:res.data   //将获取到的数据存储到listData中渲染到页面上
        })
        wx.stopPullDownRefresh();   //停止下拉刷新状态
      }
    })
  }
})

2. Back-end implementation

Use PHP to obtain the corresponding data for the paging request parameters passed by the front-end and return it to the mini program front-end.

<?php
$pageNo=$_GET['pageNo'];   //获取当前的页码
$pageSize=10;   //每页数据的数量
$offset=($pageNo - 1)* $pageSize;   //计算分页的偏移量
//使用PDO连接数据库
$dsn='mysql:host=localhost;dbname=test;charset=utf8';
$pdo=new PDO($dsn,'root','');
//查询总记录数
$sql="SELECT count(id) FROM table_name";
$stmt=$pdo->query($sql);
$total= $stmt->fetchColumn();
//查询当前页的数据
$sql="SELECT * FROM table_name LIMIT $offset,$pageSize";
$stmt=$pdo->query($sql);
$data=array();
while($row=$stmt->fetch()){
    $data[]=$row;
} 
//将总记录数和数据返回给小程序
$result=array(
    'total' =>$total,
    'data' =>$data
);
echo json_encode($result);
?>

2. Load More

In the WeChat applet, Load More is a method that allows users to infinitely scroll the page to obtain more data. We can load more functions by listening to the onReachBottom event in the applet. The following are the specific implementation steps.

1. Front-end implementation

Add the onReachBottom listening function in the js file of the mini program page, and call the back-end interface to obtain the data of the next page.

Page({
  data: {
    listData: [],
    pageNo:1
  },
  onPullDownRefresh: function () {
    var that=this;
    //下拉刷新请求前面的步骤
  },
  onReachBottom:function(){
    var that=this;
    var pageNo=that.data.pageNo+1;   //获取下一页数据的页码
    wx.showLoading({   //显示加载状态
      title: '加载中...',
    })
    wx.request({
      url: 'http://yourdomain.com/api/getdata.php',   //后端接口地址
      data: {
        pageNo:pageNo    //请求下一页的数据
      },
      success: function (res) {
        var listData=that.data.listData.concat(res.data.data);   //将获取到的数据拼接到listData中
          that.setData({
            listData:listData,
            pageNo:pageNo    //更新页码
          })
          wx.hideLoading();   //隐藏加载状态
      }
    })
  }
})

2. Backend implementation

In PHP, for the paging request parameters passed by the front end, use PDO to query the corresponding data and return it to the applet front end.

<?php
$pageNo=$_GET['pageNo'];   //获取当前的页码
$pageSize=10;   //每页数据的数量
$offset=($pageNo - 1)* $pageSize;   //计算分页的偏移量
//使用PDO连接数据库
$dsn='mysql:host=localhost;dbname=test;charset=utf8';
$pdo=new PDO($dsn,'root','');
//查询当前页的数据
$sql="SELECT * FROM table_name LIMIT $offset,$pageSize";
$stmt=$pdo->query($sql);
$data=array();
while($row=$stmt->fetch()){
    $data[]=$row;
} 
//将数据返回给小程序
echo json_encode($data);
?>

The above are the techniques for using PHP to implement pull-down refresh and load more functions in WeChat applet. I hope that through the introduction of this article, everyone can better understand and master the way to use PHP to develop WeChat mini programs.

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