thinkphp5.0.24 控制器代码

public function getPage($tag)
{
$tag = json_decode($tag,true);
$itemId = isset($tag['itemId']) ? $tag['itemId'] : null;
$limit = isset($tag['limit']) ? $tag['limit'] : 1;
$page = isset($tag['page']) ? $tag['page'] : 1;
$type = isset($tag['type']) ? $tag['type'] : 'detail';
$itemType = isset($tag['itemType']) ? $tag['itemType'] : '';

if (!$itemId) {
return false;
}
if ($type == 'detail') {
if ($itemType == 'upPage') {
$itemList = db($this->item)->where('id','<',$itemId)->limit($limit)->order('id','DESC')->select();
}
if ($itemType == 'downPage') {
$itemList = db($this->item)->where('id','>',$itemId)->limit($limit)->order('id','ASC')->select();
}
if ($itemList) {
foreach ($itemList as $k => $v) {
$itemList[$k]['categoryInfo'] = model($this->itemCategoryModelNameSpace)->getCategoryInfo($v['cid']);
}

foreach ($itemList as $k => $v) {
$itemList[$k]['url'] = $this->getUrlByItemInfo($v);
}

return $itemList;
} else {
return false;
}
}

前台调用代码：

{mipcms:page value='val' limit='1' itemId='$itemInfo["id"]' type='detail' itemType='upPage'}
<div class="mipmb-page-item item-up-page">
<p>上一篇</p>
<a data-type="mip" href="{$val.url}">{$val.title}</a>
</div>
{/mipcms:page}
{mipcms:page value='val' limit='1' itemId='$itemInfo["id"]' type='detail' itemType='downPage'}
<div class="mipmb-page-item item-down-page ">
<p>下一篇</p>
<a data-type="mip" href="{$val.url}">{$val.title}</a>
</div>
{/mipcms:page}

以上代码实现上一篇下一篇增加按照分类筛选功能，求代码？