验证失败后如何保留HTML Select标签的用户输入？

你的select标签无法保留用户输入的问题，根源在三个细节上：

• 变量名冲突：你把存储用户提交值的变量和选项数组都命名为$type，导致用户的输入被数组覆盖。
• 选中判断逻辑错误：$t == $type是拿单个选项字符串和整个数组比较，永远不会相等，自然不会有选项被标记为选中。
• 错误使用select属性：<select>标签本身不支持value属性，选中状态完全靠<option>的selected属性控制，加了也无效。

修正后的select代码 #

<label>Brick Type: </label>
<select name='type'>
    <?php
    // 单独存储用户提交的选择，避免和选项数组重名
    $selected_type = $_POST['type'] ?? '';
    // 选项数组换个名字区分
    $types = ['', "A grade Red/Cream brick $2", "B grade Red/Cream brick $1.50", "Red/Cream clinkers $2.50"];
    foreach ($types as $t){
        // 拿单个选项和用户提交的值对比，匹配则添加selected属性
        $select = ($t == $selected_type) ? 'selected' : '';
        echo "<option value='$t' $select>$t</option>";
    }
    ?>
</select>

完整修正后的表单代码 #

<form action="index.php" method="post" novalidate="true">
    <div class="box"><h1>Brick Order</h1></div>​
    <fieldset>
        <label>Customer Name:
            <span class="error">
                <?= $errors['cusName']??'';?>
            </span>
        </label>
        <input type='text' name='cusName' value="<?= $cusName??'';?>"/>
        <br>
     
              
        <label>Mobile:
            <span class='error'>
                <?= $errors["mobile"]??'';?>
            </span>
        </label>
        <input type='text' name='mobile' maxlength="10" value="<?= $mobile??'';?>"/>
        <br>        
        
        
        <label>Preferred delivery date:</label>
        <input type='date' name='delivery' value="<?= $date??'';?>"/>
        <br>
           
        
        <label>Number of Bricks:
            <span class='error'>
                <?= $errors["num_bricks"]??'';?>
            </span>
        </label>
        <input type='number' name='num_bricks' value="<?= $num_bricks??'';?>"/>
        <br>        
  
        
        <label>Brick Type: </label>
        <select name='type'>
            <?php
            $selected_type = $_POST['type'] ?? '';
            $types = ['', "A grade Red/Cream brick $2", "B grade Red/Cream brick $1.50", "Red/Cream clinkers $2.50"];
            foreach ($types as $t){
                $select = ($t == $selected_type) ? 'selected' : '';
                echo "<option value='$t' $select>$t</option>";
            }
            ?>
        </select>
        <br>   
    </fieldset>
    <button type="submit" name="submit">SEND</button>
</form>

修改后，表单验证失败刷新页面时，就能正确保留用户之前选择的砖型了。

内容的提问来源于stack exchange，提问作者clappersk