使用 PHP 和 jQuery returns 的无限滚动分页只有少数帖子和加载器 gif 暂停

Question

我正在尝试使用 PHP 和 JQuery 复制在线找到的无限滚动代码。

但不幸的是，代码中存在一个缺陷，它只允许 return 7 个帖子，并且在向下滚动时停止获取其他帖子，在底部留下加载器 gif。

Generally, I wouldn't have asked this question, but the code seems pretty nice (in laymans terms) which I presume will be very helpful for rookies like me in the community.

同时会搜索其他资源，自己尝试解答

我的代码如下：

Index.php

<div class="post-wall">
        <div id="post-list">
            <?php
            require_once ('db.php');
            $sqlQuery = "SELECT * FROM tbl_posts";
            $result = mysqli_query($conn, $sqlQuery);
            $total_count = mysqli_num_rows($result);
            
            $sqlQuery = "SELECT * FROM tbl_posts ORDER BY id DESC LIMIT 7";
            $result = mysqli_query($conn, $sqlQuery);
            ?>
            <input type="hidden" name="total_count" id="total_count"
            value="<?php echo $total_count; ?>" />

            <?php
            while ($row = mysqli_fetch_assoc($result)) {
                $content = substr($row['content'], 0, 100);
                ?>
                <div class="post-item" id="<?php echo $row['id']; ?>">
                    <p class="post-title"><?php echo $row['title']; ?></p>
                    <p><?php echo $content; ?></p>
                </div>
                <?php
                }
                ?>
            </div>
            <div class="ajax-loader text-center">
                <img src="LoaderIcon.gif"> Loading more posts...
            </div>
    </div>

<script type="text/javascript">
$(document).ready(function(){
        windowOnScroll();
});
function windowOnScroll() {
       $(window).on("scroll", function(e){
        if ($(window).scrollTop() == $(document).height() - $(window).height()){
            if($(".post-item").length < $("#total_count").val()) {
                var lastId = $(".post-item:last").attr("id");
                getMoreData(lastId);
            }
        }
    });
}

function getMoreData(lastId) {
       $(window).off("scroll");
    $.ajax({
        url: 'getMoreData.php?lastId=' + lastId,
        type: "get",
        beforeSend: function ()
        {
            $('.ajax-loader').show();
        },
        success: function (data) {
               setTimeout(function() {
                $('.ajax-loader').hide();
            $("#post-list").append(data);
            windowOnScroll();
               }, 1000);
        }
   });
}
</script>

getMoreData.php

<?php
require_once('db.php');

$lastId = $_GET['lastId'];
$sqlQuery = "SELECT * FROM tbl_posts WHERE id < '" .$lastId . "' ORDER BY id DESC LIMIT 7";

$result = mysqli_query($conn, $sqlQuery);


while ($row = mysqli_fetch_assoc($result))
 {
    $content = substr($row['content'],0,100);
    ?>
    <div class="post-item" id="<?php echo $row['id']; ?>">
        <p class="post-title">  <?php echo $row['title']; ?></p>
        <p><?php echo $content; ?></p>
    </div>
    <?php
}
?>

非常感谢任何帮助。

Answer 1

我会使用类和控制器等进行不同的设置，但作为简单的脚本，我可能会设置如下：

使用以下内容创建名为 getData.php 的文件：

<?php

require_once('db.php');

if (! function_exists('getData')) {
    /**
     * @param int $offset
     * @param int $limit
     * @return array|null
     */
    function getData($offset, $limit, $conn) {
         $offset = (int)$offset;
         $limit  = (int)$limit;
         $sqlQuery = "SELECT * FROM tbl_posts ORDER BY id DESC LIMIT $limit OFFSET $offset";
         $result = mysqli_query($conn, $sqlQuery);
         $rows = [];
         while ($row = mysqli_fetch_assoc($result)) {
             $rows[]= $row;
         }
         return $rows;
     }
}

使用以下内容创建另一个名为 index.php 的文件：

<?php
require_once ('getData.php');

$offset = (int)($_GET['offset'] ?? 0);
$dataOnly = (int)($_GET['dataOnly'] ?? 0);
$limit = 7;
$rows = getData($offset, $limit, $conn);
$offset+= $limit;
$data = [
    'rows' => $rows,
    'offset' => $offset,
];


$data = json_encode($data);

// if this is an ajax call, stop here and just spit out our json
if ($dataOnly) {
    echo $data;
    exit;
}
// otherwise, render the page
$sqlQuery = "SELECT * FROM tbl_posts";
$result = mysqli_query($conn, $sqlQuery);
$total_count = mysqli_num_rows($result);
?>

<!DOCTYPE html>
<html>
<head>
    <script type="text/javascript" src="jquery-3.2.1.min.js"></script>
    <style type="text/css">
        body {
            font-family: Arial;
            background: #e9ebee;
            font-size: 0.9em;
        }

        .post-wall {
            background: #FFF;
            border: #e0dfdf 1px solid;
            padding: 20px;
            border-radius: 5px;
            margin: 0 auto;
            width: 500px;
        }

        .post-item {
            padding: 10px;
            border: #f3f3f3 1px solid;
            border-radius: 5px;
            margin-bottom: 30px;
        }

        .post-title {
            color: #4faae6;
        }

        .ajax-loader {
            display: block;
            text-align: center;
        }
        .ajax-loader img {
            width: 50px;
            vertical-align: middle;
        }
    </style>
</head>
<body>
<div class="post-wall">
    <div id="post-list">
        <input type="hidden" name="total_count" id="total_count" value="<?= $total_count ?>" />
        <input type="hidden" name="offset" id="offset" value="<?= $offset ?>" />
    </div>
    <div class="ajax-loader text-center">
        <img src="LoaderIcon.gif"> Loading more posts...
    </div>
</div>

<script type="text/javascript">
    $(document).ready(function(){
// load the initial rows on page load
        let initialData = <?= $data ?? '' ?>;
        if (initialData) {
            if (initialData.rows) {
                addrows(initialData.rows);
                $('.ajax-loader').hide();
            }
        }
        windowOnScroll();

    });
    function windowOnScroll() {
        $(window).on("scroll", function(e){
            if ($(window).scrollTop() == $(document).height() - $(window).height()){
                console.log('test');
                if($(".post-item").length < $("#total_count").val()) {
                    let offset = $('#offset').val();
                    getMoreData(offset)
                }
            }
        });
    }

    function getMoreData(offset) {
        $('.ajax-loader').show();
        $(window).off("scroll");
        let pageUrl = window.location.href.split('?')[0];
        $.ajax({
            url: pageUrl + '?dataOnly=1&offset=' + offset,
            type: "get",
            success: function (response) {
                response = JSON.parse(response);
                if (response.rows) {
                    addrows(response.rows);
                    if (response.offset) {
                        $('#offset').val(response.offset);
                    }
                    $('.ajax-loader').hide();
                }
                windowOnScroll();
            }
        });
    }

    function addrows(rows) {
        let postList = $("#post-list");
        $.each(rows, function (i, row) {
            let rowHtml = '<div class="post-item" id="'+row.id+'"><p class="post-title">'+row.title+'</p><p>'+row.content+'</p></div>';
            postList.append(rowHtml);
        });
    }
</script>
</body>
</html>

现在，我无法在本地对此进行测试，因此其中可能会出现一两个错误，但这应该能让您大致了解。

有一件事我不能 100% 确定 if ($(window).scrollTop() == $(document).height() - $(window).height()){ 条件。

XSS 警告

您没有说明这些“帖子”是如何添加到数据库中的，大概它们来自用户以其他形式提交的内容。如果是这种情况，请确保您了解 what XSS vulnerabilities are and how to prevent them

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XSS 警告