javascript - 迭代集合对象 MongoDB 时如何使用 forEach？

Question

请建议我如何从数据库中进行选择，将集合中的 ID 与数组的每个元素进行比较？不幸的是，下面的代码返回了一个空数组:

index(req, res) {
    Room.find({_id: req.user.rooms.forEach((item)=>{
            return item;
        })
    })
        .then((rooms) => {
            console.log(rooms)
            res.send(rooms)
        }
        )
        .catch(err => res.status(400).json(err));
}

req.user.rooms - 该数组的每个项目都是 ID，我想将其与集合 Room 中的内容进行比较。

Answer 1

他们的文档中非常简单地介绍了如何 query items in a list .

您的代码应如下所示:

index(req, res) {
    // Additional validation should be done to make sure that req.user.rooms 
    // is an array with length > 0. I'll leave that for you to do.
    const rooms = req.user.rooms;

    Room.find({ _id: rooms})
        .then((rooms) => {
            console.log(rooms)
            res.send(rooms)
        })
        .catch(err => res.status(400).json(err));
}

<小时/>

除此之外，您实际上不应该从 Controller 执行数据库查询； it's not a good architectural practice这就是它在 Node 服务中的样子

roomController.js

const RoomService = require("/path/to/services/directory"); // Let services contain all business logic. Don't give them anything related to your web server framework

async index(req, res) {
    // Additional validation should be done to make sure that req.user.rooms 
    // is an array with length > 0. I'll leave that for you to do.
    try {
       const rooms = await RoomService.retrieveById(req.user.rooms);
       res.send( { success: true, data: rooms } ); // We send back the result when we get one
    } catch ( err ) {
       // We respond to the client with our error, ideally you'll log it too
       res.status( err.statusCode ).send( { success: false, error: err } );
    }
    
}

RoomService.js

const Room = require("/path/to/your/model");

module.exports = {
  retrieveById: async function(ids) {
     try {
       return await Room.find({ _id: ids}); // Typically this would be abstracted to a DB layer. but putting it here for brevity
     } catch( err ) { 
       throw new Error( err ); // This is caught in our controller, which we send to client
     }
     
  }
};