Question

开发node.js应用。由于某种原因，即使我已验证req.params.id有效且应返回数据，该findOne调用始终返回未定义的值。

let event = await Event.findOne({ venue: ObjectId(req.params.id) });

我也尝试过......

let event = await Event.findOne({ venue: req.params.id });

这是我的Event模型定义的一部分。...

const EventSchema = new mongoose.Schema({
  eventDate: {
     type: Date
  },
  venue: {
     type: mongoose.Schema.ObjectId,
     ref: 'Venue'
  },

在邮递员中，我正在针对 / venues / 5e0401c4a246333ca4ced332 网址执行 Delete http动词。

基本上，我想在事件表中搜索场地ID。在决定删除它之前，我正在查看某个事件是否正在使用该场所。

这是整个方法...

// @desc    Delete venue
// @route   DELETE /api/v1/venues/:id
// @access  Private
exports.deleteVenue = asyncHandler(async (req, res, next) => {
  let venue = await Venue.findById(req.params.id);

  if (!venue) {
    return next(
      new ErrorResponse(`No venue with the id of ${req.params.id}`, 404)
    );
  }

  if (req.user.role !== 'manager' && req.user.role !== 'admin') {
    return next(new ErrorResponse(`Not authorized to delete venue`, 401));
  }

  // the following line always returns undefined even though the venue 
  // exists in the events table.... then it jumps to the end of the method
  let event = await Event.findOne({ venue: ObjectId(req.params.id) });

  if (event) {
    return next(
      new ErrorResponse(
        `You cannot delete a venue because events are tied to it.`,
        404
      )
    );
  }

  await Venue.remove();

  res.status(200).json({
    success: true,
    data: {}
  });
});

使用指南针，查看事件集合，我肯定会看到使用我提交的ID的记录...

_id:5e045b6e0c38f2502440ecb7
attendees:Array
eventDate:2020-01-01T05:00:00.000+00:00
venue:5e0401c4a246333ca4ced332
status:"planning"

我做到了...

  console.log(`id is ${req.params.id}`);
  let event = await Event.findOne({ venue: req.params.id });

结果显示我正在传递正确的ID。...（控制台输出）

id is 5e0401c4a246333ca4ced332
ReferenceError: Event is not defined
    at C:\Projects\abc\controllers\venues.js:90:15

任何见识将不胜感激。谢谢！

Answer 1

似乎您没有导入事件模型。您需要添加：

const Event = require("../models/event"); //you need to change the path

之后，您需要找到以下事件： Event.findOne({ venue: req.params.id })。

我还有一些建议：

1-）在开始时检查角色授权更有意义。

2-）首先检查给定场地是否有任何活动，如果没有活动，请使用findByIdAndDelete方法。这样，由于我们消除了Venue.findById

，因此可以减少数据库访问的数量

3-）如果场地有事件，则使用404状态代码似乎不正确。我认为400-错误的请求更合适。

4-）猫鼬会转换_id，因此无需使用ObjectId。

exports.deleteVenue = asyncHandler(async (req, res, next) => {

  if (req.user.role !== "manager" && req.user.role !== "admin") {
    return next(new ErrorResponse(`Not authorized to delete venue`, 401));
  }

  let event = await Event.findOne({ venue: req.params.id });

  if (event) {
    return next(new ErrorResponse(`You cannot delete a venue because events are tied to it.`,400));
  }

  let venue = await Venue.findByIdAndDelete(req.params.id);

  console.log(venue);
  if (!venue) {
    return next(new ErrorResponse(`No venue with the id of ${req.params.id}`, 404));
  }

  res.status(200).json({
    success: true,
    data: {}
  });
});

测试：

假设我们有以下两个Venue文档。

{
    "_id" : ObjectId("5e0471e3394d1e2b348b94aa"),
    "name" : "Venue 1",
},
{
    "_id" : ObjectId("5e0471eb394d1e2b348b94ab"),
    "name" : "Venue 2",
}

还有一个活动文档，其地点为1号地点，ID为5e0471e3394d1e2b348b94aa：

{
    "_id" : ObjectId("5e04727c76da213f8c9bf76a"),
    "eventDate" : ISODate("2019-12-26T11:41:16.019+03:00"),
    "name" : "Event 1",
    "venue" : ObjectId("5e0471e3394d1e2b348b94aa")
}

当我们要删除Venue 1时，将发生以下错误，因为它有一个事件：

You cannot delete a venue because events are tied to it.，状态码为400。

Answer 2

用猫鼬和Expressjs的findOneAndDelete来做到这一点：

const express = require("express");
const router = express.Router();

router.delete("/:id", (req, res) => {
  if (!mongoose.Types.ObjectId.isValid(req.params.id)) { //checking if id valid
    return res.send("Please provide valid id");
  }
  var id = mongoose.Types.ObjectId(req.params.id);  // passing it into a var
  Event.findOneAndDelete({ venue: id }).then( res.json({ success: true }));
});

module.exports = router;

了解详情https://mongoosejs.com/docs/api/query.html#query_Query-findOneAndDelete

Answer 3

exports.deleteVenue = asyncHandler(async (req, res, next) => {

  //First check role. Because it not call database
  if (req.user.role !== 'manager' && req.user.role !== 'admin') {
    return next(new ErrorResponse(`Not authorized to delete venue`, 401));
  }

  //Next step, check event
  const event = await Event.findById({ venue: ObjectId(req.params.id) });

  if (event) {
    return next(
      new ErrorResponse(
        `You cannot delete a venue because events are tied to it.`,
        404
      )
    );
  }

  //Delete venue by Id
   await Venue.deleteOne({ id: req.params.id }, (error, result) =>{
      if(error) return next(
      new ErrorResponse(`No venue with the id of ${req.params.id}`, 404)
    );

      res.status(200).json({
         success: true,
         data: {}
       });
   })

});

通过objectId进行的findOne筛选始终返回未定义

3 个答案: