Mongoose findbyid / find({id: "..."}) returning Null - mongodb

Question

I have seen this asked several times, but I haven't found a solution that has worked. I am trying to query a MongoDB using Mongoose .findById and am not getting the expected results. find({id: "..."}) is also not returning anything.
Using find without any parameters displays all of the expected results including id key-value pairs, but I cannot use the id value in the query.
Using mongoose: 5.4.9
const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/mongo-exercises', { useNewUrlParser: true });
const courseSchema = new mongoose.Schema({
name: String,
author: String,
tags: [String],
date: { type: Date, default: Date.now },
isPublished: Boolean,
price: Number
});
const Course = mongoose.model('Course', courseSchema);
async function getCourses() {
return await Course
.find()
}
async function run() {
const result = await getCourses();
console.log(result);
}
run();
//Return
[ { tags: [ 'react', 'frontend' ],
_id: 5a68fdf95db93f6477053ddd,
date: 2018-01-24T21:43:21.589Z,
name: 'React Course',
author: 'Mosh',
isPublished: false,
__v: 0 },
{ tags: [ 'aspnet', 'backend' ],
_id: 5a68fde3f09ad7646ddec17e,
date: 2018-01-24T21:42:59.605Z,
name: 'ASP.NET MVC Course',
author: 'Mosh',
isPublished: true,
price: 15,
__v: 0 },
{ tags: [ 'node', 'backend' ],
_id: 5a68fe2142ae6a6482c4c9cb,
date: 2018-01-24T21:44:01.075Z,
name: 'Node.js Course by Jack',
author: 'Jack',
isPublished: true,
price: 12,
__v: 0 },
{ tags: [ 'node', 'backend' ],
_id: 5a68fdd7bee8ea64649c2777,
date: 2018-01-24T21:42:47.912Z,
name: 'Node.js Course',
author: 'Mosh',
isPublished: true,
price: 20,
__v: 0 },
{ tags: [ 'node', 'backend' ],
_id: 5a68ff090c553064a218a547,
date: 2018-01-24T21:47:53.128Z,
name: 'Node.js Course by Mary',
author: 'Mary',
isPublished: false,
price: 12,
__v: 0 },
{ tags: [ 'angular', 'frontend' ],
_id: 5a6900fff467be65019a9001,
date: 2018-01-24T21:56:15.353Z,
name: 'Angular Course',
author: 'Mosh',
isPublished: true,
price: 15,
__v: 0 },
{ tags: [ 'express', 'backend' ],
_id: 5a68fdc3615eda645bc6bdec,
date: 2018-01-24T21:42:27.388Z,
name: 'Express.js Course',
author: 'Mosh',
isPublished: true,
price: 10,
__v: 0 } ]
That code verifies I'm connected to the correct database and retrieving real ids. When I modify the getCourses function as shown below, I get null or an empty array depending on whether I use findById or find({id: "..."}).
async function getCourses() {
return await Course
.findById('5a68fdf95db93f6477053ddd')
}
//null
async function getCourses() {
return await Course
.find({ id: '5a68fdf95db93f6477053ddd' })
}
// []
async function getCourses() {
return await Course
.find({ _id: '5a68fdf95db93f6477053ddd' })
}
// []
Any help would be greatly appreciated. Thank you!
EDIT: Showing full find() response.

Answer 1

Upon our discussion as your importing the data from JSON file, So its inserting the _id as string, While finding the document by _id, moognoose automatically converting string to Object.
// Original JSON
{
"_id": "5a68fde3f09ad7646ddec17e",
"tags": [
"aspnet",
"backend"
],
"date": "2018-01-24T21:42:59.605Z",
"name": "ASP.NET MVC Course",
"author": "Mosh",
"isPublished": true,
"price": 15,
"__v": 0
}
Solution 1 :
To insert the _id as in the JSON, change your _id field with $oid as below,
{
"_id": { "$oid": "5a68fde3f09ad7646ddec17e" },
"tags": [
"aspnet",
"backend"
],
"date": "2018-01-24T21:42:59.605Z",
"name": "ASP.NET MVC Course",
"author": "Mosh",
"isPublished": true,
"price": 15,
"__v": 0
}
Solution 2 :
Remove _id from your JSON, MongoDB will generate a _id automatically
{
"tags": [
"aspnet",
"backend"
],
"date": "2018-01-24T21:42:59.605Z",
"name": "ASP.NET MVC Course",
"author": "Mosh",
"isPublished": true,
"price": 15,
"__v": 0
}