没有现成的api，自己写吧

let ret = {}, tb = db.collection(‘xxx’), wh = tb.where({***}),

{ total = -1 } = await wh.count()

if (total == -1){

    ret = { error:1 }

} else if (total > 0){

    ret = await wh.update({

        data:{***}

    })

} else {

    ret = await tb.add({

        data:{***}

    })

}

return ret