exports.main = async (event, context) => {
	//event为客户端上传的参数
	console.log('event : ', event)
       //客户端传过来的分类id
	const cateid = event.cateid
	const db = uniCloud.database()
	const dbCmd = db.command
	let res = await db.collection('opendb-news-articles').aggregate()
	  .lookup({
		from: 'opendb-news-categories',
		localField: 'category_id',
		foreignField: '_id',
		as: 'List',
	  })
	  .match({
    	        category_id:dbCmd.eq(cateid)
	  })
	  .end()
	//返回数据给客户端
	
	return res
	
};

w我想查询某分类下的文章，为啥返回为空啊，不加.match会返回全部文章，加了之后返回为空数组。是我哪里写错了吗？