【发布时间】：2019-01-24 23:31:59
【问题描述】：
我们正在为我们的网站制作投票系统。您可以将报告发布到网站上，这些报告保存为数据文件。
当前的问题是用户可以根据需要多次投赞成票或反对票，因为没有阻止投票的障碍。我们希望用户能够投赞成票或投反对票一次。
我们正在尝试使用 cookie 来实现这一点（我知道，这不是最好的系统，因为人们只能清除 cookie，但这是一个小型学生项目，我们只需要关闭系统）。我们可以在 upvote 和 downvote 脚本中设置 cookie。我们有一个 vote cookie，它可以设置为 0、-1 或 1，具体取决于用户是否投票。
但是，我们无法准确检索 cookie。当我们尝试使用$_COOKIE["vote"] 检索cookie vote 时，它没有给我们一个值。
这个cookie 没有返回值有什么原因吗？先感谢您。如果您需要，下面提供了我们所有的代码。
<?php
$report = $_GET["report"];
if(!isset($_COOKIE["vote"])) {
setcookie("vote", "0", time() + 315360000, $_SERVER['REQUEST_URI']);
$_COOKIE["vote"] = "0";
}
function upvote() {
if(file_exists("DataUploads/".$GLOBALS['report'])) {
if($_COOKIE["vote"] == "1") { // Problem: $_COOKIE is not being compared to "1" properly, always returns false
$filename = "DataUploads/".$GLOBALS['report'];
$line = 3;
$lines = file($filename, FILE_IGNORE_NEW_LINES);
$lines[$line] = (string)((int)$lines[$line] - 1);
file_put_contents($filename, implode("\n", $lines));
setcookie("vote", "0", time() + 315360000, $_SERVER['REQUEST_URI']);
$_COOKIE["vote"] = "0";
} else {
$filename = "DataUploads/".$GLOBALS['report'];
$line = 3;
$lines = file($filename, FILE_IGNORE_NEW_LINES);
if($_COOKIE["vote"] == "-1") {
$lines[$line] = (string)((int)$lines[$line] + 2);
} else {
$lines[$line] = (string)((int)$lines[$line] + 1);
}
file_put_contents($filename, implode("\n", $lines));
setcookie("vote", "1", time() + 315360000, $_SERVER['REQUEST_URI']);
$_COOKIE["vote"] = "1";
}
}
}
function downvote() {
if(file_exists("DataUploads/".$GLOBALS['report'])) {
if($_COOKIE["vote"] == "-1") {
$filename = "DataUploads/".$GLOBALS['report'];
$line = 3;
$lines = file($filename, FILE_IGNORE_NEW_LINES);
$lines[$line] = (string)((int)$lines[$line] + 1);
file_put_contents($filename, implode("\n", $lines));
setcookie("vote", "0", time() + 315360000, $_SERVER['REQUEST_URI']);
$_COOKIE["vote"] = "0";
} else {
$filename = "DataUploads/".$GLOBALS['report'];
$line = 3;
$lines = file($filename, FILE_IGNORE_NEW_LINES);
if($_COOKIE["vote"] == "1") {
$lines[$line] = (string)((int)$lines[$line] - 2);
} else {
$lines[$line] = (string)((int)$lines[$line] - 1);
}
file_put_contents($filename, implode("\n", $lines));
setcookie("vote", "-1", time() + 315360000, $_SERVER['REQUEST_URI']);
$_COOKIE["vote"] = "-1";
}
}
}
if($_POST["upvote_x"]) {
upvote();
}
if($_POST["downvote_x"]) {
downvote();
}
?>
<!DOCTYPE html>
<html lang="en"><head><meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
<link rel="stylesheet" href="styles.css">
<title>View Report</title>
<link rel="icon" href="Images/favicon.ico" type="image/x-icon">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
<div class="header"></div>
<div id="navbar">
<ul>
<li><a href="index.html">Home</a></li>
<li><a href="about.html">About</a></li>
<li><a href="submit.html">Submit</a></li>
<li><a href="submissions.php">View</a></li>
</ul>
</div>
<div id="content">
<ul style="list-style-type: none;">
<?php
if(file_exists("DataUploads/".$GLOBALS['report'])) { // Check if the report exists
echo '<h2>Report Information:</h2>';
$data = file("DataUploads/".$GLOBALS['report']); // Gets array of lines in file
$upvote_button_url = $_COOKIE["vote"] == "1"?"Images/upvote.png":"Images/upvote_noclick.png";
$downvote_button_url = $_COOKIE["vote"] == "-1"?"Images/downvote.png":"Images/downvote_noclick.png";
echo '<h3 style="display:inline">Votes: </h3><p style="display:inline" class="wordwrap">'.$data[3].'</p>';
if($data[4] == "demo") {
echo "<br>";
echo "This is a demonstrational report, and cannot be voted on.";
echo "<br>";
} else {
echo '<form method="post">';
echo '<input type="image" src="'.$upvote_button_url.'" name="upvote" id="upvote" value="Upvote" onclick="changeUpvoteImage()" /><br/>';
echo '<input type="image" src="'.$downvote_button_url.'" name="downvote" id="downvote" value="Downvote" onclick="changeDownvoteImage()" /><br/>';
echo '</form>';
echo '<p>If a report has or has less than -40 votes, it will be deleted.</p>';
}
if(file_exists('ImageUploads/'.pathinfo($GLOBALS['report'], PATHINFO_FILENAME))) {
echo '<li><img src="ImageUploads/'.$GLOBALS['report'].'" style="max-height: 600px; max-width: 700px"></li>';
} else {
echo '<img src="Images/missing.png" width="25%"><br>';
}
echo '<li><h3 style="display:inline">Location: </h3><p style="display:inline" class="wordwrap">'.htmlspecialchars($data[0]).'</p></li>';
echo '<li><h3 style="display:inline">Description: </h3><p style="display:inline" class="wordwrap">'.htmlspecialchars($data[1]).'</p></li>';
echo '<li><b><h3 style="display:inline">Urgency: </h3>';
if($data[2] < 30) {
echo "<span style='color: #1f7725'>Low</span>";
} else if($data[2] < 50) {
echo "<span style='color: #77711e'>Medium</span>";
} else if($data[2] < 80) {
echo "<span style='color: #774e1e'>High</span>";
} else {
echo "<span style='color: #771e1e'>Immediate</span>";
}
echo "</b></li>";
function delete() {
if(file_exists("DataUploads/".$GLOBALS['report'])) {
unlink("DataUploads/".$GLOBALS['report']); //delete file
}
if(file_exists("ImageUploads/".$GLOBALS['report'])) {
unlink("ImageUploads/".$GLOBALS['report']); //delete file
}
}
if($data[3] <= -40 && $data[4] != "demo") {
delete();
}
} else {
echo '<h1>No report found with the name "'.$GLOBALS['report'].'". Check the URL!</h1>';
echo '<img src="Images/missing-report.jpg" width="50%">';
}
?>
</ul>
<br>
<br>
<br>
</div>
<script>
function getUrlVars() {
var vars = {};
var parts = window.location.href.replace(/[?&]+([^=&]+)=([^&]*)/gi, function(m,key,value) {
vars[key] = value;
});
return vars;
}
function getCookieValue(a) {
var b = document.cookie.match('(^|;)\\s*' + a + '\\s*=\\s*([^;]+)');
return b ? b.pop() : '';
}
function changeUpvoteImage() {
var img = document.getElementById("upvote");
img.src = "Images/upvote.png";
return false;
}
function changeDownvoteImage() {
var img = document.getElementById("downvote");
img.src = "Images/downvote.png";
return false;
}
if(getCookieValue(getUrlVars("report") + "vote") == 1) {
changeUpvoteImage();
} else if(getCookieValue(getUrlVars("report") + "vote") == -1) {
changeDownvoteImage();
}
</script>
<script>
if(window.history.replaceState) {
window.history.replaceState(null, null, window.location.href);
}
</script>
</body>
</html>
【问题讨论】：
-
使用
session代替cookie。某些浏览器需要很长时间才能更新或删除cookie，但如果更改，会话会立即更新。 -
我会使用会话，但我希望投票永久持续，而不是在用户关闭浏览器时。
标签： php cookies server backend