How to implement the list of PHP development in WeChat applet by scrolling to the bottom

With the popularity of smartphones, more and more applications are beginning to move to mobile terminals. As one of the development models, WeChat applet has received more and more attention. In the development process of small programs, how to scroll the list to the bottom to view more data is a relatively common requirement. This article will introduce how to use PHP to develop and implement this function in WeChat applet.

1. The principle of automatic loading when scrolling to the bottom

Before introducing the specific implementation method, let us first understand the principle of automatic loading when scrolling to the bottom. In fact, the core idea to implement this function is very simple, that is, use the onReachBottom method provided by the WeChat applet. This method is triggered when the user scrolls to the bottom of the list, and then sends a request to the server to obtain more data and display it.

2. How to scroll to the bottom of the PHP development implementation list

1. Write a PHP interface

First, we need to write a PHP interface for The client sends data. In this interface, we need to parse the parameters passed by the client, such as the current page number, the number of items displayed on each page, etc., and query the corresponding data from the database based on these parameters and return it to the client. Therefore, we need to be proficient in the related operations of PHP and MySQL.

The following is a simple PHP code snippet:

<?php
$currentPage = $_POST['currentPage'];
$pageSize = $_POST['pageSize'];
$offset = ($currentPage - 1) * $pageSize;

$sql = "SELECT * FROM table LIMIT $offset,$pageSize";
$result= mysqli_query($conn, $sql);

$response = array();
$data = array();
while($row = mysqli_fetch_assoc($result)){
      array_push($data, $row);
}
mysqli_free_result($result);
mysqli_close($conn);
$response['success'] = true;
$response['data'] = $data;
echo json_encode($response);
?>

2. Send a request in the mini program

Next, we need to send a request in the WeChat mini program Send a request to the server to get data. Before implementing this function, we need to introduce the third-party library wxrequest.js into the applet. This library can help us easily send asynchronous requests and obtain data.

Call the wx.request method to send the request code as follows:

wx.request({
  url: 'https://example.com/getList',
  data: {
    currentPage: currentPage,
    pageSize: pageSize
  },
  method: 'POST',
  header: {
    'content-type': 'application/x-www-form-urlencoded'
  },
  success: function (res) {
    // 处理返回数据
    if (res.data.success) {
      var l = res.data.data.length;
      var newData = l ? (that.data.list.concat(res.data.data)) : [];

      // 更新数据
      that.setData({
        list: newData      })
    } 
  }
})

Among them, url is the server address that sends the request, data is the request data, method is the request method, header is the request header, and success is Callback function when the request is successful.

3. Listen to scroll events

In the last step of implementing this function, we need to listen to the list scroll event and trigger the onReachBottom event of the WeChat applet when scrolling to the bottom. Send a request through this event to obtain more data and display it.

The code is as follows:

// 监听页面滑动事件
onPageScroll: function(e) {
  // 滚动到底部，触发onReachBottom事件
  if(e.scrollHeight - e.scrollTop === e.clientHeight) {
    if(!this.data.loading) {
      this.setData({
        loading: true
      })
      // 加载下一页数据
      this.getList();
    }
  }
},

// onReachBottom事件：加载下一页数据
onReachBottom: function () {
  if (!this.data.loading) {
    this.setData({
      loading: true
    })
    // 加载下一页数据
    this.getList();
  }
},

// 获取列表数据
getList: function () {
  var that = this;
  var currentPage = that.data.currentPage + 1;
  var pageSize = that.data.pageSize;
  wx.request({
    url: 'https://example.com/getList',
    data: {
      currentPage: currentPage,
      pageSize: pageSize
    },
    method: 'POST',
    header: {
      'content-type': 'application/x-www-form-urlencoded'
    },
    success: function (res) {
      // 处理返回数据
      if(res.data.success) {
        var l = res.data.data.length;
        var newData = l ? (that.data.list.concat(res.data.data)) : [];
        // 更新数据
        that.setData({
          list: newData,
          currentPage: currentPage
        })
      }
      that.setData({
        loading: false
      })
    }
  })
}

Through the introduction of this article, I believe you have learned how to use PHP development to scroll the list to the bottom in the WeChat applet. This is a relatively simple and practical development method that does not require too much reliance on third-party libraries and is more flexible in development. At the same time, implementing this function is also an important step in the development of mini programs, which can improve the user experience and optimize the efficiency of user operations.

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