list.phpにちょっと書き足し

/data/class/pages/products/LC_Page_Products_List.phpに以下を追加

104行目辺りから書き替え

        //表示条件の取得
		/*
        $this->arrSearchData = array(
            'category_id'   => $this->lfGetCategoryId(intval($this->arrForm['category_id'])),
            'maker_id'      => intval($this->arrForm['maker_id']),
            'name'          => $this->arrForm['name']
        );
		*/
		
		if(is_array($_GET['category_id'])){
			$arrCategory_id = array();
			if(preg_match("/^[0-9]+$/" , $_GET['category_id'][0])) array_push($arrCategory_id, $_GET['category_id'][0]);
			if(preg_match("/^[0-9]+$/" , $_GET['category_id'][1])) array_push($arrCategory_id, $_GET['category_id'][1]);
			if(preg_match("/^[0-9]+$/" , $_GET['category_id'][2])) array_push($arrCategory_id, $_GET['category_id'][2]);
			$this->arrSearchData = array(
				'category_id'   => $arrCategory_id
			);
		}else{
			$this->arrSearchData = array(
				'category_id'   => $this->lfGetCategoryId(intval($this->arrForm['category_id'])),
				'maker_id'      => intval($this->arrForm['maker_id']),
				'name'          => $this->arrForm['name']
			);
		}
        $this->orderby = $this->arrForm['orderby'];

		// サブカテゴリリストを取得
		$this->arrSubCatList = $this->getSubCatList($this->arrSearchData['category_id']);

最後尾に追加

	/*
	 *  子カテゴリ一覧を取得
	 *
	 *  @param  int $category_id 該当カテゴリID
	 *  @return Array $arrSubCatList 子カテゴリID
	 */
	function getSubCatList($category_id){
		$arrRet = SC_Helper_DB_Ex::sfGetCatTree();
		$cnt = 0;
		foreach($arrRet as $key => $val){
			if($val['parent_category_id'] == $category_id){
				$arrSubCatList[$cnt]['category_id'] = $val['category_id'];
				$arrSubCatList[$cnt]['category_name'] = $val['category_name'];
				$cnt++;
			}
		}
		return $arrSubCatList;
	}	

tplに表示するコードを書いて完了

/data/Smarty/templates/sphone/products/list.tplに以下を追加

<!--{if $arrSubCatList|@count > 0}-->
<section class="under_category">
	<div class="title_box_sub clearfix">
	    <h2>下層カテゴリ一覧</h2>
	      <span class="b_expand"><img src="<!--{$TPL_URLPATH}-->img/common/btn_minus.png" onclick="fnSubToggle($('#sub_areaxx'), this);" alt=""></span>
	 </div>
	    <div id="sub_areaxx" class="toggle_block">
		<ul>
	    <!--{foreach from=$arrSubCatList item=category}-->
	    <li>
	        <a href="<!--{$smarty.const.ROOT_URLPATH}-->products/list.php?category_id=<!--{$category.category_id|h}-->"><!--{$category.category_name|h}--></a>&nbsp;
	    </li>
	    <!--{/foreach}-->
		</ul>
	    </div>
</section>
<!--{/if}-->