db.action is not a function

'use strict';  
const db = uniCloud.database()  
exports.main = async (event, context) => {  
    //event为客户端上传的参数  

    const query = event.queryStringParameters  
    let dbs  
    // const {  
    //  type="detail"  
    // } = query  
    const type="detail"  
    if (type == "artical") {  
        const pageSize = query.pageSize || 10  
        const page = query.page || 1  
        dbs = await db.collection('user-artical').skip((page - 1) * pageSize).limit(Number(pageSize)).get()  
    } else if (type == "life") {  
        const pageSize = query.pageSize || 12  
        dbs = await db.collection('life').skip((page - 1) * pageSize).limit(Number(pageSize)).get()  
    } else if (type == "intro") {  
        dbs = await db.collection('life').get()  
    } else if (type == "detail") {  
        console.log('db:',db);  
        // dbs = await db.action("readnum").collection('user-artical').where({  
        //  _id: query.id  
        // }).get()  
    }  

    //返回数据给客户端  
    return dbs  
};