下拉列表ajax

Question

有人可以查看我的代碼，看看是什么導致第二個下拉列表無法填充嗎？ 我不太清楚為什么。 先感謝您。

視圖：

    <div id="finder">
    <div class="form">
    <select id="brand" name="brand" onchange="myFunction()" >
        <option value="">&nbsp;&nbsp;- Printer Brand -&nbsp;&nbsp;</option>
        <?php foreach ($categories as $category_1) { ?>
        <?php if ($category_1['category_id'] == $category_id) { ?>
        <option value="<?php echo $category_1['category_id']; ?>" selected="selected"><?php echo $category_1['name']; ?></option>
        <?php } else { ?>
        <option value="<?php echo $category_1['category_id']; ?>"><?php echo $category_1['name']; ?></option>
        <?php } ?>
        <?php } ?>
    </select>
    </div>

    <br>

<div class="form">
    <select name="printerSeries" id="printerSeries">
    <option value="">&nbsp;&nbsp;- Printer Series -&nbsp;&nbsp;</option>

    </select>
  </div>
  <br>

Javascript Ajax調用

 <script type="text/javascript"> function myFunction(){ var brand_id = document.getElementById("brand").value; $.ajax({ url: 'index.php?route=common/home/getSeries&brand_id=' + brand_id, type: 'post', dataType: 'json', success: function(json) { $('#printerSeries').append('<option value="<?php echo $json['category_id']; ?>" Selected="selected"><?php echo $json['name']; ?></option>'); } error: function(){ alert('error'); } }); } </script> 

這是接收json請求的控制器功能

    public function getSeries($brand){
$brand_id = $_POST['brand_id'];
$json = array();
$categories_2 = $this->model_catalog_category->gettoner($brand_id);

    foreach ($categories_2 as $category_2) {

        $json = array(
            'category_id' => $category_2['category_id'],
            'name'        => $category_2['name'],
        );


}
    $this->response->addHeader('Content-Type: application/json');
    $this->response->setOutput(json_encode($json));


    }

Answer 1

這里的問題可能是由以下功能引起的：$ this-> model_catalog_category-> gettoner（$ brand_id）;

檢查函數是否在每種情況下都返回一個值。 如果沒有，只需返回任何值。將出現您的下拉菜單。