有条件的 if 内部变量

Question

我有nav.php，里面有 2 个变量。我想通过回显变量将nav.php 包含在index.php 中。 nav.php代码如下：

<?php 
$TopLeftNav = '<li if ($_SERVER['PHP_SELF'] == "/dashboard.php") echo "class = 'active'" ><a href="dashboard.php">Dashboard</a></li>
<li if ($_SERVER['PHP_SELF'] == "/website.php") echo "class = 'active'" ><a href="website.php">Add Website</a></li>
<li php if ($_SERVER['PHP_SELF'] == "/report.php") echo "class = 'active'" ><a href="report.php">Reports</a></li>';

$TopRightNav = '<a class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse">
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
            </a>';
?>

如您所见，变量$TopLeftNav 不起作用，因为其中的if 条件。条件是突出显示当前活动页面。

我知道我可以通过创建单独的文件（例如 nav1.php、nav2.php）和分离导航 html 来使它们工作，但出于学习目的，我该如何解决这个问题？提前致谢。

Answer 1

你可以这样做：

<?php 
// set the variables we will use to an empty string
$web_class = '';
$dash_class = '';
$report_class = '';

// check the PHP_SELF and set a variable
if ($_SERVER['PHP_SELF'] == "/website.php") {
    $web_class  = 'active';
} elseif ($_SERVER['PHP_SELF'] == "/dashboard.php") {
    $dash_class  = 'active';
} elseif ($_SERVER['PHP_SELF'] == "/report.php") {
    $report_class  = 'active';
}

// generate the output
$TopLeftNav = '<li class="'.$dash_class.'"><a href="dashboard.php">Dashboard</a></li>';
$TopLeftNav .= '<li class="'.$web_class.'"><a href="website.php">Add Website</a></li>';
$TopLeftNav .= '<li class="'.$report_class.'"><a href="report.php">Reports</a></li>';

$TopRightNav = '<a class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse">
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
            </a>';
?>

虽然我更倾向于做这样的事情：（一个 switch 语句）http://php.net/manual/en/control-structures.switch.php

<?php

// set the variables we will use to an empty string
$web_class = '';
$dash_class = '';
$report_class = '';


switch through the PHP_SELF and set the variables accordingly
switch ($_SERVER['PHP_SELF']){
    case '/dashboard.php':
        $dash_class  = 'active';
        break;
    case '/report.php':
        $report_class  = 'active';
        break;
    case '/website.php':
        $web_class  = 'active';
        break;
}

// generate the output
$TopLeftNav = '<li class="'.$dash_class.'"><a href="dashboard.php">Dashboard</a></li>';
$TopLeftNav .= '<li class="'.$web_class.'"><a href="website.php">Add Website</a></li>';
$TopLeftNav .= '<li class="'.$report_class.'"><a href="report.php">Reports</a></li>';

$TopRightNav = '<a class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse">
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                </a>';
?>

switch 语句非常适合这种事情，因为当您在几年后再次使用它时，生成的代码更具可读性。

Answer 2

这应该适合你：

这里我使用这样的三元运算符：

(conditional expression) ? (ouput if true) : (output if false);

<?php 
    $TopLeftNav = '<li  ' . ($_SERVER['PHP_SELF'] == "/dashboard.php" ? ' class = \'active\' ' : '') . ' ><a href="dashboard.php">Dashboard</a></li>
    <li  ' . ($_SERVER['PHP_SELF'] == "/website.php" ? ' class = \'active\' ' : '') . ' " ><a href="website.php">Add Website</a></li>
    <li ' . ($_SERVER['PHP_SELF'] == "/report.php" ? ' class = \'active\' ' : '') . ' " ><a href="report.php">Reports</a></li>';

    $TopRightNav = '<a class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse">
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                </a>';
?>

Answer 3

好的，因为其他答案看起来更像是黑客而不是有用的东西，请考虑这种方法：

<?php 
// three classes for each for easier adding them to the HTML strings
// each of them will be assigned a value of "class = 'active'" in case of matching urls
// or just an empty string otherwise
$dashboardClass = $_SERVER['PHP_SELF'] == "/dashboard.php" ? "class = 'active'" : "";
$reportClass = $_SERVER['PHP_SELF'] == "/report.php" ? "class = 'active'" : "";
$websiteClass = $_SERVER['PHP_SELF'] == "/website.php" ? "class = 'active'" : "";

$TopLeftNav = "
<li $dashboardClass><a href='dashboard.php'>Dashboard</a></li>
<li $websiteClass><a href='website.php'>Add Website</a></li>
<li $reportClass><a href='report.php'>Reports</a></li>";

$TopRightNav = '<a class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse">
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
            </a>';
?>

因此，我们的想法是为三个类中的每一个存储要回显的值（因此我们有三个新变量）。我还从单引号切换到双引号，以便直接插入 PHP 字符串，而无需连接任何内容，例如，如果 PHP_SELF 与 dashboard.php 匹配，<li $dashboardClass> 将变为 <li class='active'>，或者只是 <li>否则。

三元运算符：

这个：$dashboardClass = $_SERVER['PHP_SELF'] == "/dashboard.php" ? "class = 'active'" : ""; 和这个一样：

if ($_SERVER['PHP_SELF'] == "/dashboard.php") {
    $dashboardClass = "class = 'active'";
}
else {
    $dashboardClass = '';
}