I wanted to find the subdocument with id and return the subdocument, not the parent document, my schema are as follows :
var coursesSchema = new mongoose.Schema({
coursename:{type:String}
});
var parentSchema = new mongoose.Schema({
courses:[coursesSchema]
});
var Parent= mongoose.model('parent', parentSchema );
module.exports = Parent;
let data = Parent.courses.id(_id);
as given in the docs I tried to find the subdocument using .id, it is throwing error saying Cannot read property 'id' of undefined,
and after searching a lot found this question I tried the same, apparently it also returned the same error.
let data = Parent['courses'].id(_id);
please help me with this, I am not able to get my head around with it🙏
In order to get the subdocument, you have to do the following:
Look for the document
Reference the subdocument property
In your case, you have defined a Model. Based on this model, you would need to:
Parent.findOne({ _id: ObjectId("abcd12345678901234567890") }, function(err, doc) {
let subDocument = doc.courses;
...
}
The reason you get the "undefined" error is because the courses subdocument doesn't have a field called id. It only has a field called coursename.
We can solve this using Aggregation operations as #KunalMukherjee pointed out in the comments Here is a quick example to do so
I'm using a Mongoose/MongoDB and I'm getting some odd behaviour when I try to use the spread syntax to return values from a document after I call .save() on it.
// Npc is a Mongoose schema
const npc = new Npc({
...input,
creator: userId
});
const createdNpc = await npc.save();
I have tried using the spead operator, but the name and description keys do not exist.
return {
...createdNpc
creator: userFromId(npc.creator)
}
however when I access those values directly they ARE defined
return {
description: createdNpc.description,
name: createdNpc.name,
creator: userFromId(npc.creator)
};
I've made sure that the spelling of description and name are correct. I've tried logging both {...createdNpc} and {...createdNpc, description: createdNpc.description, name: createdNpc.name}. In the logs I've confirmed that name and description are both not defined (the keys don't exist) inside of {...createdNpc}
I have also tried logging createdNpc and {...createdNpc} and have confirmed that they return different values.
here's createdNpc:
{
_id: 5d8d5c7a04fc40483be74b3b,
name: 'NPC Name',
description: 'My Postman NPC',
creator: 5d8d50e0b5c8a6317541d067,
__v: 0
}
it doesn't actually look like a Mongoose Document at all. I would post the result of {...createdNPC} to show the difference but it's a huge code snippet and I don't want to clutter the question. I'm happy to provide it if it will help!
I'm still very new to MongoDB & Mongoose. Why would using the spread syntax on a Mongoose Document change its value?
I don't think this should be relevant to the question but just in case I'll also mention this is for a graphql resolver.
This is because Mongoose uses getters for all of its attributes. Before you use the spread operator, call createdNpc.toObject() to get a normal Object.
When viewing a sub-document with Robomongo I see something like this:
"views" : [
ObjectId("53a478431275cf0f3d91e27d"),
ObjectId("53a478431275cf0f3d91e27d")
]
But when I pull down the object through Mongoose into node.js, I see something like this:
views:
[ { _bsontype: 'ObjectID',
id: 'T\u001aôj#Ü«m¢©Ö',
viewDate: '2015-07-07T23:21:32.259Z' } ]
Yes, the schema is a little different, and I'm trying to write a script to remediate the data into the new format.
The schema is currently
views: [{view:{type: Schema.Types.ObjectId, ref: 'users'},viewDate:{type: Date, default: Date.now}}],
But
A) Why does the view object look all messed up in the latter, and
B) How can I get what I see in Robomongo? (Answered. See edit)
EDIT: Question B is answered. If I do .lean() to my query, then I'll be able to get it back as a non-mongoose object and it'll look how I expect it to look. So that just leaves question A
I managed to reproduce this.
First, you declared a schema similar to this:
views : { type : Schema.Types.ObjectId, ref : 'users' }
You created and wrote documents to the database using that schema.
Then you changed the schema to your current:
views: [{
view : { type: Schema.Types.ObjectId, ref: 'users' },
viewDate : { type: Date, default: Date.now }
}]
Using that schema, you are reading the documents that you wrote to the database using the first schema.
Those schema are fundamentally different: the first is stored as a single ObjectId in the database (the term "subdocument" is a bit confusing, because in Mongoose, subdocuments are documents that are stored with their parent document; the method you're using is called "population" in Mongoose-speak), but the second schema makes views an array of documents that have two properties (view, which is stored as an ObjectId and viewData which is a date).
This confuses Mongoose because it tries to apply the second schema to documents that were written using the first schema, and because of that, it's showing the internal representation of an ObjectId object instead of a stringified version of it.
This also explains why .lean() shows the correct results, because that tells Mongoose to return raw documents (as they are stored in the database) instead of trying to convert them according to the schema.
I am new to node.js, so I have a feeling that this will be something silly that I have overlooked, but I haven't been able to find an answer that fixes my problem. What I'm trying to do is create a path that will create a new child object, add it to the parent's array of children, then return the child object to the requester. The problem that I am running into is that if I pass the string id into findById, node crashes with
TypeError: Object {} has no method 'cast'
If I try to pass in an ObjectId instead, I get
CastError: Cast to ObjectId failed for value "[object Object]" at path "_id"
Here is a rough outline of my code:
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var ObjectId = Schema.ObjectId; //Have also tried Schema.Types.ObjectId, mongoose.ObjectId
mongoose.connect('mongodb://user:password#server:port/database');
app.get('/myClass/:Id/childClass/create', function(request, result) {
var id = new ObjectId(request.params.Id);
MyClass.findById(id).exec( function(err, myClass) {
if (err || !myClass) { result.send("error: " + err + "<br>" + JSON.stringify(id) || ("object '" + request.params.Id + "' not found: " + id)); return; }
var child = ChildClass();
myClass.Children.addToSet(child);
myClass.save();
result.send(child);
});
});
If I execute this code with the path "/myClass/51c35e5ced18cb901d000001/childClass/create", this is the output of the code:
error: CastError: Cast to ObjectId failed for value "[object Object]" at path "_id"
{"path":"51c35e5ced18cb901d000001","instance":"ObjectID","validators":[],"setters":[],"getters":[],"_index":null}
I've tried using findOne and passing in {_id:id} instead, but this appears to be exactly what findById does. I've tried the different classes for ObjectId that I've seen listed on other sites. I've tried calling ObjectId() like a function instead of a constructor and that returns undefined. At this point, I'm running out of ideas and it doesn't seem that googling for an answer is helping. Any ideas on what I'm doing wrong?
Also, like I said, I'm new to node/Mongo/Mongoose/Express, so if there is a better way to accomplish my goal, please let me know. I appreciate all feedback.
EDIT:
After the workaround from Peter Lyons, I googled another error that I was running into and found findByIdAndUpdate, which works as expected and does exactly what I was hoping to do. I'm still not sure why findById and findOne were giving me such issues and I'm curious to know (maybe a bug report needs to be filed), so I'll leave this open in case someone else has an answer.
Short answer: use mongoose.Types.ObjectId.
Mongoose (but not mongo) can accept object Ids as strings and "cast" them properly for you, so just use:
MyClass.findById(req.params.id)
However, the caveat is if req.params.id is not a valid format for a mongo ID string, that will throw an exception which you must catch.
So the main confusing thing to understand is that mongoose.SchemaTypes has stuff you only use when defining mongoose schemas, and mongoose.Types has the stuff you use when creating data objects you want to store in the database or query objects. So mongoose.Types.ObjectId("51bb793aca2ab77a3200000d") works, will give you an object you can store in the database or use in queries, and will throw an exception if given an invalid ID string.
findOne takes a query object and passes a single model instance to the callback. And findById is literally a wrapper of findOne({_id: id}) (see source code here). Just find takes a query object and passes an array of matching model instances to the callback.
Just go slow. It's confusing but I can guarantee you you are getting confused and not hitting bugs in mongoose at this point. It's a pretty mature library, but it takes some time to get the hang of it.
The other suspect thing I see in your snippet is not using new when instantiating ChildClass. Beyond that, you'll need to post your schema code in order for us to help you tract down any CastErrors that remain.
I've faced this error, That was because the value you want to filter in the _id field is not in an ID format, one "if" should solve your error.
const mongoose = require('mongoose');
console.log(mongoose.Types.ObjectId.isValid('53cb6b9b4f4ddef1ad47f943'));
// true
console.log(mongoose.Types.ObjectId.isValid('whatever'));
// false
To solve it, always validate if the criteria value for search is a valid ObjectId
const criteria = {};
criteria.$or = [];
if(params.q) {
if(mongoose.Types.ObjectId.isValid(params.id)) {
criteria.$or.push({ _id: params.q })
}
criteria.$or.push({ name: { $regex: params.q, $options: 'i' }})
criteria.$or.push({ email: { $regex: params.q, $options: 'i' }})
criteria.$or.push({ password: { $regex: params.q, $options: 'i' }})
}
return UserModule.find(criteria).exec(() => {
// do stuff
})
For all those people stuck with this problem, but still couldn't solve it: I stumbled upon the same error and found the _id field being empty.
I described it here in more detail. Still have not found a solution except changing the fields in _id to not-ID fields which is a dirty hack to me. I'm probably going to file a bug report for mongoose. Any help would be appreciated!
Edit: I updated my thread. I filed a ticket and they confirmed the missing _id problem. It is going to be fixed in the 4.x.x version which has a release candidate available right now. The rc is not recommended for productive use!
If you are having this issue and you are performing a populate somewhere along the lines, see this Mongoose issue.
Update to Mongoose 4.0 and the issue has been fixed.
Had the same problem, I just coerced the id into a string.
My schema:
const product = new mongooseClient.Schema({
retailerID: { type: mongoose.SchemaTypes.ObjectId, required: true, index: true }
});
And then, when inserting:
retailerID: `${retailer._id}`
I had the same problem, turned out after I have updated my schema, I have forgotten I was calling the model using the old id, which was created by me; I have updated my schema from something like:
patientid: {
type: String,
required: true,
unique: true
},
to
patientid: { type: mongoose.SchemaTypes.ObjectId, ref: "Patient" },
It turned out, since my code is big, I was calling the findOne with the old id, therefore, the problem.
I am posting here just to help somebody else: please, check your code for unknown wrong calls! it may be the problem, and it can save your huge headacles!
My solution is that I want data from all docs, and I don't want _id, so
User.find({}, {_id:0, keyToShow:1, keyToNotShow:0})
I was receiving this error CastError: Cast to ObjectId failed for value “[object Object]” at path “_id” after creating a schema, then modifying it and couldn't track it down. I deleted all the documents in the collection and I could add 1 object but not a second. I ended up deleting the collection in Mongo and that worked as Mongoose recreated the collection.
For the record: I had this error trying to fill a subdocument in a wrong way:
{
[CastError: Cast to ObjectId failed for value "[object Object]" at path "_id"]
message: 'Cast to ObjectId failed for value "[object Object]" at path "_id"',
name: 'CastError',
type: 'ObjectId',
path: '_id'
value:
[ { timestamp: '2014-07-03T00:23:45-04:00',
date_start: '2014-07-03T00:23:45-04:00',
date_end: '2014-07-03T00:23:45-04:00',
operation: 'Deactivation' } ],
}
look ^ value is an array containing an object: wrong!
Explanation: I was sending data from php to a node.js API in this way:
$history = json_encode(
array(
array(
'timestamp' => date('c', time()),
'date_start' => date('c', time()),
'date_end' => date('c', time()),
'operation' => 'Deactivation'
)));
As you can see $history is an array containing an array. That's why mongoose try to fill _id (or any other field) with an array instead than a Scheme.ObjectId (or any other data type). The following works:
$history = json_encode(
array(
'timestamp' => date('c', time()),
'date_start' => date('c', time()),
'date_end' => date('c', time()),
'operation' => 'Deactivation'
));
I am not sure this will help but I resolved the issue by importing mongoose like below and implementing it as below
const mongoose = require('mongoose')
_id: new mongoose.Types.ObjectId(),
I also encountered this mongoose error
CastError: Cast to ObjectId failed for value \"583fe2c488cf652d4c6b45d1\" at path \"_id\" for model User
So I run npm list command to verify the mongodb and mongoose version in my local.
Heres the report:
......
......
├── mongodb#2.2.19
├── mongoose#4.7.2
.....
It seems there's an issue on this mongodb version so what I did is I uninstall and try to use different version such as 2.2.16
$ npm uninstall mongodb, it will delete the mongodb from your node_modules directory. After that install the lower version of mongodb.
$ npm install mongodb#2.2.16
Finally, I restart the app and the CastError is gone!!
I was having the same problem.Turns out my Node.js was outdated. After upgrading it's working.
just change the path it will work for example
app.get('/myClass/:Id/childClass/create', function(request, result) .....
change to
app.get('/myClass**es**/:Id/childClass/create', function(request, result) .....
I just added --es-- to the path (myClass) to become (myClasses)
now should work and will not see that error
For me, the ID was undefined (req.params.id returns undefined)
If you're finding a document by its "_id" for a model, say Drivers, the command below works quite well:
....
const driver = await Drivers.findById(<your id>);
....
Ensure you use the async-await and try-catch ES6 syntax
For me, I was using a put request without sending any data. I changed it to a post request and it worked.
This thread covers more about put requests.
just change the path it will work for example
app.get('/myClass/:Id/childClass/create', function(request, result)
change to
app.get('/myClass**es**/:Id/childClass/create', function(request, result)
I just added --es-- to the path (myClass) to become (myClasses)
now should work and will not see that error