node.js why dose mongodb throw casting error - node.js

Question

//this error appear
{
"error": {
"message": "Cast to ObjectId failed for value \"events\" at path \"_id\" for model \"user\"",
"name": "CastError",
"stringValue": "\"events\"",
"kind": "ObjectId",
"value": "events",
"path": "_id"
}
}
//when execute this code
exports.get_all_events = (req, res, next) => {
Event.find({})
.populate("creator","name _id",user) // must define model reference
.then(result => {
console.log(result);
res.status(200).json({ result });
}).catch(err => {
console.log(err);
res.status(500).json({ error: err });
});
}
Event schema
const mongoose = require('mongoose');
// creat event schema
const eventSchema = mongoose.Schema({
name: {
type: String,
required: [true, 'name is required']
},
location: {
type: String,
required: [true, 'location is required']
},
date: {
type: String,
required: [true, 'data is required']
},
description: {
type: String,
required: [true, 'description is required']
},
creator: {
_id: {
type: mongoose.Schema.Types.ObjectId,
ref: "users"
}
}
});
module.exports = mongoose.model("events", eventSchema);
Userschema
const mongoose = require('mongoose');
const userSchema = mongoose.Schema({
email: {
type: String,
required: true,
unique: true,
match: /[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*#(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?/
},
password: {
type: String,
required: true
},
name: {
type: String,
required: true
},
post: [
{
type: mongoose.Schema.Types.ObjectId,
ref: "posts"
}
],
event: [
{
type: mongoose.Schema.Types.ObjectId,
// it point to collection
ref: "events"
}
]
});
module.exports = mongoose.model('users', userSchema);
it works great adding event to database and get single event it work but when i get all events from database throw casting error and can't make any updating on exist event

Answer 1

I think you are populating the events document little bit wrong.
Try this:
Event.find({})
.populate("creator._id","name _id")
.then(result => {
console.log(result);
res.status(200).json({ result });
}).catch(err => {
console.log(err);
res.status(500).json({ error: err });
});
I dont think you need any third argument in the .populate() function, You have already defined in your schema, where it should be populated from:
//look here, you have already defined it in your schema
creator: {
_id: {
type: mongoose.Schema.Types.ObjectId,
ref: "users" //this says which collection it should be populated from
}
}
I hope it helps you out.