Question

我有一个像这样的选择下拉列表：

<select name="city" id="order_form_select">
    <option value="" disabled selected>Ort ↓</option>
    <option>Option 1</option>
    <option>Option 2</option>
    <option>Option 3</option>
    <option>Option 4</option>
</select>

我正在收到一些这样的单选按钮：

<?php
$statement = $pdo->prepare('SELECT some_column FROM my_table WHERE some_value = "abc" AND city = :city');
$statement->execute(array('city' => $city));
$row = $statement->rowCount();
if ($row == 0) {
   echo "<input type=\"radio\" name=\"something\" value=\"option1\">Option 1</p>";
}

$statement = $pdo->prepare('SELECT some_column FROM my_table WHERE some_value = "xyz" AND city = :city');
$statement->execute(array('city' => $city));
$row = $statement->rowCount();
if ($row == 0) {
    echo "<input type=\"radio\" name=\"something\" value=\"option2\">Option 2</p>";
}
?>

如您所见，这些单选按钮取决于选择选项。这意味着，只要用户更改了选择选项，PHP代码就必须刷新，但选择框选项必须保持登录状态。

这样做的正确/常用方法是什么？

Answer 1

假设您每次选择值时都要刷新页面：

创建此javascript

<script type="text/javascript">
window.onload = function () {
    var citySelector = document.getElementById('order_form_select');
    citySelector.addEventListener('change', function () {
        if (this.value) {
            window.location = 'yourphp.php?city=' + this.value
        }
    }, false);
}
</script>

在您的html代码中，为您的选项添加值：

<select name="city" id="order_form_select">
    <option value="" disabled selected>Ort ↓</option>
    <option value="City1">Option 1</option>
    <option value="City2">Option 2</option>
    <option value="City3">Option 3</option>
    <option value="City4">Option 4</option>
</select>

要在刷新后保持该值：

<select name="city" id="order_form_select">
    <option value="" disabled <?php echo !isset($_GET['city']) ? 'selected' : ''; ?>>Ort ↓</option>
    <option value="City1" <?php echo isset($_GET['city']) && $_GET['city'] == 'City1' ? 'selected' : ''; ?>>Option 1</option>
    <option value="City2" <?php echo isset($_GET['city']) && $_GET['city'] == 'City2' ? 'selected' : ''; ?>>Option 2</option>
    <option value="City3" <?php echo isset($_GET['city']) && $_GET['city'] == 'City3' ? 'selected' : ''; ?>>Option 3</option>
    <option value="City4" <?php echo isset($_GET['city']) && $_GET['city'] == 'City4' ? 'selected' : ''; ?>>Option 4</option>
</select>

已修改版本：

如果您想避免使用javascript来执行此任务，您可以改变您的方法：

<form action="yourphpfile.php" method="GET">
  <select name="city" id="order_form_select">
    <option value="" disabled <?php echo !isset($_GET['city']) ? 'selected' : ''; ?>>Ort ↓</option>
    <option value="City1" <?php echo isset($_GET['city']) && $_GET['city'] == 'City1' ? 'selected' : ''; ?>>Option 1</option>
    <option value="City2" <?php echo isset($_GET['city']) && $_GET['city'] == 'City2' ? 'selected' : ''; ?>>Option 2</option>
    <option value="City3" <?php echo isset($_GET['city']) && $_GET['city'] == 'City3' ? 'selected' : ''; ?>>Option 3</option>
    <option value="City4" <?php echo isset($_GET['city']) && $_GET['city'] == 'City4' ? 'selected' : ''; ?>>Option 4</option>
    </select>
 <input type="submit" value="search by city">
</form>

希望这有助于你

更改选择选项时，再次从数据库获取数据

1 个答案: