Question

我没有完全得到下面的代码，但我在下面有一个下拉菜单，我希望它在下面显示这些值：

1
1/2
2
2/3
3
3/4
4
4/5

...

10

现在我也希望能够在提交后保留选项，所以我在下面尝试了这个代码，但问题是它只显示值1/2, 2/3, 3/4, 4/5...等。

foreach ($years as $year) {
    if ($validSubmission && $year == $getduration) {
         if ($year != $max_year) {
         $nextYear = $year + 1;
      $durationHTML .= "<option value='" . $year . "' selected='selected'>$year/$nextYear</option>".PHP_EOL;      
     }else{
    $durationHTML .= "<option value='" . $year . "' selected='selected'>$year</option>".PHP_EOL;  
}
}else{
         if ($year != $max_year) {
         $nextYear = $year + 1;
    $durationHTML .= "<option value='" . $year . "'>$year/$nextYear</option>".PHP_EOL;
}else{
    $durationHTML .= "<option value='" . $year . "'>$year</option>" . PHP_EOL;
     }
}
}

下面的origanl代码显示正确的选项，但没有执行$ validSubmission变量，因此在提交页面后它不会保持选项的选择：

foreach ($years as $year) {
    $durationHTML .= "<option>$year</option>".PHP_EOL;  
    if ($year != $max_year) {
         $nextYear = $year + 1;
         $durationHTML .= "<option>$year/$nextYear</option>".PHP_EOL;              
    }
}
$durationHTML .= '</select>';

以下代码确实会在提交后显示该选项，但不会在值之间显示/的值：

 foreach ($years as $year) {
        if ($validSubmission && $year == $getduration) {
            $durationHTML .= "<option value='" . $year . "' selected='selected'>$year</option>" . PHP_EOL;
        } else {
            $durationHTML .= "<option value='" . $year . "'>$year</option>" . PHP_EOL;
        }
    }

但是尝试将两种代码结合起来并没有奏效，这就是我遇到的问题

Answer 1

尝试此修改/简化代码。通过使用ternary comparison - $var = condition ? if_true : if_false - 来设置selected='selected'属性，您可以最小化代码（从~17行到~9）。

foreach ($years as $year) {

    //Gets the single years - 1,2,3...
    $sel =($validSubmission && $year == $getduration)? " selected='selected'": "";
    $durationHTML .= "<option value='$year'$sel>$year</option>".PHP_EOL;

    //Gets the double years - 1/2,2/3,3/4...
    if ($year != $max_year) {
    $nextYear = $year + 1;
    $sel =($validSubmission && ($year.'/'.$nextYear) == $getduration)? " selected='selected'": "";
    $durationHTML .= "<option value='$year/$nextYear'$sel>$year/$nextYear</option>".PHP_EOL;  
    }
}

如何在下拉菜单中显示正确的选项并显示保留选项

1 个答案: