How can I save mongoose data? It doesn’t work

var userid 


User.find({ name: "송형준" }).then(result =>{
    result.forEach(result => {
        userid = result._id
    })
});

const create_room = new Room({
    room_name: 'sexy',
    user_list: `${userid}`,
})

create_room.save()

I’ve been trying to run this code.
But it doesn’t work.
I think the ploblem is in the grammar