猫鼬：TypeError：'mongooseSchemahere'不是一个函数

Question

I have the following mongoose Schema setup in models/user.js:

const mongoose = require('mongoose');

const userSchema = mongoose.Schema({

    loginId: String,
    firstname: String,
    lastname: String,
    eMail: String,
    password: String,
    active: Boolean

});

module.exports = userSchema; 

In my main app.js I have the following code:

const mongoose = require('mongoose');
var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/";

MongoClient.connect(url,  {
  useUnifiedTopology: true,
  useNewUrlParser: true,
  },function(err, db) {
  if (err) throw err;
  var dbo = db.db("db");
  dbo.collection("db").find({}).toArray(function(err, result) {
    if (err) throw err;
    console.log(result);
    db.close();
  });
}); 

let userSchema = require('./models/user.js');
// Get single user
app.get('/user/:id', function (req, res) {
  userSchema.findById(req.params.id, (error, data) => {
    if (error) {
      return next(error)
    } else {
      res.json(data)
    }
  })
})

I get the error which is in the title (just replace mongooseSchemahere with userSchema). What did I do wrong? I tried putting the userSchema declaration in different places, it did not help..

Answer 1

You need to export the model and not the schema.

const mongoose = require('mongoose');

const userSchema = mongoose.Schema({
    loginId: String,
    firstname: String,
    lastname: String,
    eMail: String,
    password: String,
    active: Boolean

});

module.exports =  mongoose.model('user', userSchema);

Now you can do things like:

let User = require('./models/user.js');
// Get single user
app.get('/user/:id', function (req, res) {
  User.findById(req.params.id, (error, data) => {
    if (error) {
      return next(error)
    } else {
      res.json(data)
    }
  })
})

Answer 2

You need to use mongoose.connect to work with mongoose models.

Make these changes:

1-) Create the user model like this and export:

const mongoose = require("mongoose");

const userSchema = new mongoose.Schema({
  loginId: String,
  firstname: String,
  lastname: String,
  eMail: String,
  password: String,
  active: Boolean
});

module.exports = mongoose.model("User", userSchema);

2-) Change your App.js to connect your db with mongoose.connect:

const express = require("express");
const app = express();
const mongoose = require("mongoose");
const User = require("./models/user");
const url = "mongodb://localhost:27017/mydb";

const port = process.env.PORT || 3000;

app.use(express.json());

mongoose
  .connect(url, {
    useNewUrlParser: true,
    useUnifiedTopology: true
  })
  .then(() => {
    app.listen(port, () => {
      console.log(`App running on port ${port}...`);
    });
  })
  .catch(error => console.log(error));

Now you can create a user like this:

app.post("/user", function(req, res, next) {
  console.log("Req body:", req.body);
  User.create(req.body)
    .then(result => {
      console.log({ result });
      res.send(result);
    })
    .catch(err => {
      console.log(err);
      res.status(500).send("something went wrong");
    });
});

To retrieve the user by _id:

app.get("/user/:id", function(req, res, next) {
  User.findById(req.params.id, (error, data) => {
    if (error) {
      return next(error);
    } else {
      res.json(data);
    }
  });
});

To retrieve a user by firstname: (if you want to find all users by firstname change findOne to find.):

app.get("/user/firstname/:firstname", function(req, res, next) {
  console.log(req.params.firstname);
  User.findOne({ firstname: req.params.firstname }, (error, data) => {
    if (error) {
      return next(error);
    } else {
      res.json(data);
    }
  });
});