PHP、HTML、Javascript -从foreach循环创建交互式下拉菜单

Question

我正在做一个投票页面，在那里用户可以投票在几个投票，其中有不同的答案取决于类别。要保持简单，请执行以下操作：

代码说明

我有两个foreach循环:第一个循环遍历所有的投票，并将它们打印出来。第二个迭代遍历调查的所有可用答案。从category_id收到多个应答。答案打印在每个民意测验下面。它目前的显示方式是，每个民意调查及其相应的答案都打印在彼此的下方，有点像一个列表。

我想要的是

我想有一个下拉菜单，其中显示所有可用投票时被点击。当点击投票时，它必须显示投票本身和相应的答案。

代码

<!-- Voting form --> 
<h3> Pollpagina </h3>
<?php
    //prepare statement to select all polls
    $get_polls = $db->prepare('SELECT * FROM polls');
    $get_polls->execute();
    $all_polls = $get_polls->fetchAll();
    //treat every poll as an individual poll
    foreach($all_polls as $single_poll) {
?>  
        <!-- Create a form for each poll, with the corresponding answers as radio buttons -->
        <form method="post" action="">
            <div class="poll">
<?php
                //get textual poll and its corresponding id and category
                $poll_id = $single_poll['id'];
                $poll = $single_poll['poll'];
                $category = $single_poll['category_id'];
                //echo each poll
                echo $poll, "<br>";
                //prepare statement for getting all the answers from a specific category
                $category_answers = $db->prepare('SELECT answer FROM answers WHERE category_id = ?');
                $category_answers->bindValue(1, $category, PDO::PARAM_STR);
                $category_answers->execute();
                $all_answers = $category_answers->fetchAll();
                //create a radio button for each answer
                foreach($all_answers as $single_array_answer) {
                    $single_answer = array_shift($single_array_answer);
?>
                    <input type="radio" name="radio" value="<?php print_r($single_answer); ?>"> <?php print_r($single_answer); ?>  <br>
<?php
                }
?>
                <!-- If a vote has been submitted, the value tag will send the corresponding poll id -->
                <button type="submit" name="submit" value="<?php print_r($poll_id); ?>"</button>Submit
            </div>
        </form>
<?php
    }
?>

Answer 1

要显示投票，请执行以下操作：

<select id="dropdown">
   <?php
     echo "<option value='$pollId'>$pollName</option>";
   ?>
</select>

要显示所有调查答案，请使用jquery：

$("#dropdown").on("change",function){
  <?php
   /*
      print all poll answers here 
   */
?>;
}