存在文档时，MongoDB .find() 返回 null

Question

我是 MongoDB 的新手，目前正在关注 a blog tutorial，它教我如何使用 MERN 堆栈构建网站。

问题

问题出在后端，尤其是从后端检索文档。我自己（通过网站）将文档插入数据库进行测试。它位于一个名为“Articles”的集合中：

_id:613c75edd38cd146c0b8a1df
title:"An experimental evaluation of test driven development vs. test-last de..."
authors:"Munir, H., Wnuk, K., Petersen, K., Moayyed, M."
source:"EASE"
pubyear:"2014"
doi:"https://doi.org/10.1145/2601248.2601267"
claim:"code quality improvement"
evidence: "strong support"

我的文件

以下是文章数据库模型：

const mongoose = require('mongoose')

const ArticleSchema = new mongoose.Schema({
    id: {
        type: Number
    },
    title: {
        type: String,
        required: true
    },
    authors: {
        type: String,
        required: true
    },
    source: {
        type: String,
        required: true
    },
    pubyear: {
        type: String,
        required: true
    },
    doi: {
        type: String,
        required: true
    },
    claim: {
        type: String,
        required: true
    },
    evidence: {
        type: String,
        required: true
    }


});

module.exports = Articles = mongoose.model('Articles', ArticleSchema);

路线如下：

// routes/api/articles.js

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

// Load Articles model
const Articles = require('../../models/Articles');
console.log(Articles);

// @route GET api/articles/test
// @description tests articles route
// @access Public
router.get('/test', (req, res) => res.send('articles route testing!'));

// @route GET api/articles
// @description Get all articles
// @access Public
router.get('/', (req, res) => {
  Articles.find()
    .then(articles => res.json(articles))
    .catch(err => res.status(404).json({ noarticlesfound: 'No articles found' }));
});

// @route GET api/articles/:id
// @description Get single articles by id
// @access Public
router.get('/:id', (req, res) => {
  Articles.findById(req.params.id)
    .then(article => res.json(article))
    .catch(err => res.status(404).json({ noarticlefound: 'No article found' }));
});

// @route GET api/articles
// @description add/save articles
// @access Public
router.post('/', (req, res) => {
  Articles.create(req.body)
    .then(article => res.json({ msg: 'Article added successfully' }))
    .catch(err => res.status(400).json({ error: 'Unable to add this article' }));
});

// @route GET api/article/:id
// @description Update article
// @access Public
router.put('/:id', (req, res) => {
  Articles.findByIdAndUpdate(req.params.id, req.body)
    .then(article => res.json({ msg: 'Updated successfully' }))
    .catch(err =>
      res.status(400).json({ error: 'Unable to update the Database' })
    );
});

// @route GET api/article/:id
// @description Delete article by id
// @access Public
router.delete('/:id', (req, res) => {
  Articles.findByIdAndRemove(req.params.id, req.body)
    .then(article => res.json({ mgs: 'Article entry deleted successfully' }))
    .catch(err => res.status(404).json({ error: 'No such a article' }));
});

module.exports = router;

后端完美运行。当我去测试路线时，它会返回预期的字符串。但它似乎在检索任何内容时总是返回一个空集合 ([])。

我的 app.js 文件：

// app.js

const express = require('express');
const connectDB = require('./config/db');
var cors = require('cors');

// routes
const articles = require('./routes/api/articles');

const app = express();

// Connect Database
connectDB();

// cors
app.use(cors({ origin: true, credentials: true }));

// Init Middleware
app.use(express.json({ extended: false }));

app.get('/', (req, res) => res.send('Hello world!'));

// use Routes
app.use('/api/articles', articles);

const port = process.env.PORT || 8085;

app.listen(port, () => console.log(`Server running on port ${port}`));

我的尝试

我在 Stack Overflow 上看到的大多数问题似乎都与 db.collection.find 类似，但在本教程中它并没有说明如何检索这样的数据，因此我无法尝试大多数修复.

我确实在 Articles 集合中注意到 id 实际上是 _id，所以我对文章的数据库模型进行了更改，但没有任何变化。

Answer 1

这是我通常遵循的格式，但您能否包含此修改并检查它是否有效？
我尝试使用不同的数据库，它对我有用。

router.get("/", function (req, res) {
  Articles.find({}, function (err, allDetails) {
    if (err) {
      console.log(err);
    } else {
      res.json(allDetails);
    }
  });
});