如何使用参数设置 Express 路由

Question

我正在构建一个 MEVN 堆栈 CRUD 应用程序（Vue、Node、Express、MongoDB）。我正在尝试为我的应用设置以下 Express 路由...

postRoutes.get('/view/:id', async (req, res) => {
  const collection = await loadPostsCollection();
  let id = req.params.id;
  res.send(await collection.find({}).toArray());
  res.status(201).send();
});

...以便它根据数据的 id 从 MongoDB 返回特定数据。我不知道如何设置res.send 以便它根据req.params.id 查找数据。我试着像这样传递req.params.id...

postRoutes.get('/edit/:id', async (req, res) => {
  const collection = await loadPostsCollection();
  let id = req.params.id;
  res.send(await collection.find({ _id: mongodb.ObjectId(req.params.id)}).toArray());
  res.status(201).send();
});

...但这也没有用。知道如何设置此路由以根据 ID 参数查找数据吗？谢谢！

我的完整 Express 路由器页面如下：

const express = require('express');
const postRoutes = express.Router();
const mongodb = require('mongodb')


postRoutes.get('/', async (req, res) => {
  const collection = await loadPostsCollection();
  res.send(await collection.find({}).toArray());
});


postRoutes.post('/add', async (req, res) => {
  const collection = await loadPostsCollection();
  let task = req.body;
  await collection.insertOne(task);
  res.status(201).send();
});

postRoutes.get('/view/:id', async (req, res) => {
  const collection = await loadPostsCollection();
  let id = req.params.id;
  res.send(await collection.find({}).toArray());
  res.status(201).send();
});

postRoutes.delete('/delete/:id', async (req, res, next) => {
  const collection = await loadPostsCollection();
  collection.deleteOne({ _id: mongodb.ObjectId(req.params.id) });
  res.status(200).send({});
});

async function loadPostsCollection() {
  const client = await mongodb.MongoClient.connect(
    '...',
    {
      useNewUrlParser: true
    }
  );
  return client.db("test").collection("todos")
}

module.exports = postRoutes;

Answer 1

你最好使用findOne这样的方法：

const { ObjectID } = require("mongodb");

postRoutes.get("/view/:id", async (req, res) => {
  const collection = await loadPostsCollection();
  let id = req.params.id;

  let result = await collection.findOne({
    _id: new ObjectID(id)
  });

  if (!result) {
    return res.status(400).send("Not found");
  }

  res.status(200).send(result);
});

Answer 2

如果您需要来自数据库的特定数据，那么您需要使用 findById 方法并传递您的 id 而不是 find 方法：

postRoutes.get('/edit/:id', async (req, res) => { const collection = await loadPostsCollection(); let id = req.params.id; res.send(await collection.findById(id).toArray()); res.status(201).send(); });

postRoutes.get('/view/:id', async (req, res) => { const collection = await loadPostsCollection(); let id = req.params.id; res.send(await collection.findById(id).toArray()); res.status(201).send(); }); 

postRoutes.delete('/delete/:id', async (req, res, next) => { const collection = await loadPostsCollection(); collection.deleteOne({ _id:req.params.id}); res.status(200).send({}); });

Answer 3

您需要在查找查询中传递过滤器，即

postRoutes.get('/view/:id', async (req, res) => {
  const collection = await loadPostsCollection();
  let id = req.params.id;
  const o_id = new mongo.ObjectID(id);
  const result=await collection.find({ id: o_id });
  res.status(201).send(result.toArray());
});

此外，您不能为一个请求发送两次响应，因此请省略一个 resp.send()。