具有无限子类别的下拉嵌套类别->Ajax/Laravel

我的数据库->带字段的表产品类别: -身份证 -类别名称 -父ID级别 -您是否处于活动状态

要检索类别的我的产品实体:

    public function getAjaxGetCategoriesDropdown() {
        $categories = DB::table('product_categories')
            ->where('is_active', 1)
            ->orderBy('path', 'asc')
            ->select('categoryName','level','id','parentId')
            ->get();

    $first = array();
    $children = array();
    foreach ($categories as $cat) {
        if ($cat->level == 2) {
            $first[$cat->id] = $cat;
        } else if ($cat->parentId) {
            $children[$cat->parentId][] = $cat;
        }
    }
    return array('first' => $first, 'children' => $children);
}

public function create()
{
    $cats = $this->product->getAjaxGetCategoriesDropdown();
    return View('products/create_product')->with(compact('products','cats'));
}

视图:(create.blade.php)

<div class="section">
  <label class="field select">
        <select id="first_cat" class="required-entry validate-select" onchange="showCat(this, 2)">
      <option value=""> Select a Category </option>
        <?php foreach ($tree['first'] as $cat): ?>
      <option value="<?php echo $cat->id ?>"><?php echo $cat->categoryName ?></option>
<?php endforeach ?>
</select>
<i class="arrow double"></i>
</label>
<div id="sub_cat"></div>
</div>

<script type="text/javascript">
    var children = $H(<?php echo json_encode($tree['children']) ?>);

    function showCat(obj, level) {
        var catId = obj.value;
        level += 1;
        if ($('cat_container_' + level)) {
            $('cat_container_' + level).remove();
        }
        if (children.get(catId)) {
            var options = children.get(catId);
            var html = '<select id="cat_' + catId + '" onchange="showCat(this, ' + level + ')">' + '<option value="">Select a SubCategory</option>';
            for (var i = 0; i < options.length; i++) {
                html += '<option value="' + options[i].entity_id + '">' + options[i].name + '</option>';
            }
            html += '</select>' + '<i class="arrow double"></i>';
            html = '<label class="field select ' + 'cat_container_' + level + '">' + html + '</label>';

            $('sub_cat').insert(html);
        }
    }
</script>

日志显示的当前错误为:

create.blade.php中未定义的变量树

.. 代码 <?php foreach ($tree['first'] as $cat): ?>

我已经在一个Magento应用程序上成功地使用了这段代码,但是现在将同样的方法移植到Laravel并没有显示结果。谢谢你的帮助。