TypeError：无法读取猫鼬上未定义的属性“查找”

Question

我是 MongoDB Atlas 的新手。我正在尝试使用 mongoose 在我的“test2”数据库中查询当前存在的集合“dogs”。

我正在使用 nodeJS 来执行查询

var mongoose = require('mongoose');    
mongoose.connect('mongodb+srv://*****:*******b@cluster0-uln4x.mongodb.net/test?retryWrites=true&w=majority', {
useUnifiedTopology: true,
useNewUrlParser: true,
})
.then(() => console.log('DB Connected!!!'))
.catch(err => {
console.log('did not work');    });    
var db = mongoose.connection;   
db.on('error', console.error.bind(console, 'connection error:'));

db.once('open', function() {
    db.dogs.find().forEach(printjson);     //ERROR!
 });

导致错误：TypeError: Cannot read property 'find' of undefined

狗怎么是undefined？

Answer 1

在您的代码中dogs 必须是猫鼬模型，还将 mongoDB 连接字符串更改为test2，请试试这个：

var mongoose = require('mongoose');
mongoose.connect('mongodb+srv://*****:*******b@cluster0-uln4x.mongodb.net/test2?retryWrites=true&w=majority', {
    useUnifiedTopology: true,
    useNewUrlParser: true,
})
    .then(() => console.log('DB Connected!!!'))
    .catch(err => {
        console.log('did not work', err);
    });
var db = mongoose.connection;
db.on('error', console.error.bind(console, 'connection error:'));

const dogsSchema = new mongoose.Schema({
    any: {}
});

const Dogs = mongoose.model('dogs', dogsSchema, 'dogs');

db.once('open', function () {
    Dogs.find().lean(true).exec((err, data) => {
        console.log('Err ::', err, 'data ::', data)
    })
});