Find() Method MongoDB with Nodejs

Question

I'm currently trying to find all the documents that have a certain value of 'bar' in the key 'foo'. Using mongodb and nodejs.

When I try to run this I get: "TypeError: Cannot read property 'find' of undefined" error return.

If I try using findOne() it'll just return the first document that has the document with the value "bar" for the key "foo", however there are 3.

module.exports = function(app, db) {

app.get('/foo', (req, res)=>{

db.collection('barCollection').find({foo: {$all: ['bar']}}
,(err, item)=>{
 if (err) {
            res.send({'error':'An error has occurred'});
        } else {
            res.send(item);
        } 
    });
 });
};

Thanks

Answer 1

Paul is right, there is some issue in your code which is why it's returning null.

Here try this snippet. I'm using 2 files for demo.

model.js

const mongoose = require('mongoose');

mongoose.connect('mongo_url');
var barSchema = new mongoose.Schema({
  // your schema
});

module.exports = mongoose.model('Bar', barSchema);

main.js

var BarCollection = require('./models'); // assuming both files are in same directory.

BarCollection.find({foo: {$all: ['bar']}}
,(err, item)=>{
 if (err) {
            res.send({'error':'An error has occurred'});
        } else {
            res.send(item);
        } 
    });
 });
};

Basically what I am trying here is:

1. separate MongoDB model code in separate files
2. Import mongo collection in API files for CRUD operations

Answer 2

db.collection('barCollection') is returning null for some reason. You'll need to figure out why, it's probably somewhere else in your code since you don't have the setup logic here.

I'd look at whether mongodb was connected properly (i.e. is the db instance you're passing that function actually connected to the database), is mongodb running and available on the port you configured it with, etc.