I'm using mongoose 5.0.9. My question is about the _id of document.
I'd like to get `_id generated from mongodb when new document inserted. In this way, I could not define the _id in my mongoose schema/model. If I do, the mongoose will fail since I don't provide the value for _id.
However, I want to use the _id in my page. If I don't define it in my schema/model, I could not get it when querying.
One solution I thought is to define two schemas: one for inserting document without _id, and the other is for querying, updating, etc, with _id.
I don't want to make things to complex, so I don't think this is good idea.
what is the best practice for this _id?
Thanks in advance.
Richard
Related
I'm using Node.js v8.12.0, MongoDB v4.0.4 & Mongoose v5.3.1.
I want to update an embedded array subdocument without changing its position in array index. And without loading the entire array in memory because that array might get very big in future.
I spent a lot of time searching how to achieve this but without luck.
I've tried to use Mongo's $elemMatch to load the document with only single relevant array subdocument, but that wouldn't let me save the subdocument in any practical way.
I've also looked into Mongoose array set method, but for this you need to have subdocument array index, so this mean I need to load the entire array into a memory and then find subdocument index.
Is there any way to achieve what I want? Ideally via Mongoose abstractions, so all Mongoose middleware like validations, plugins, etc. kick in.
Actually found the answer right after submitting this question.
For anyone looking it up in future, you can use special $ operator in combination with $set. (I'm not sure if that makes use of mongoose middlewares, though. I need to do some testing around that).
Here's some code example, which queries some subdocument using _id, and then updates that subdocument property someProperty using $set which uses special operator $ that matches queried subdocument array position/index.
var doc = await SomeModel.findOneAndUpdate(
{'someArray._id': 'xxx'},
{'$set': {'someArray.$.someProperty': 'someValue'}},
);
It's still not 100% what I'm looking for, though. Because the returned doc still has full array of subdocuments (I assume that's still loaded into memory?), and it seems that I can't use $elemMatch in combination with $set.
In my case, further down the road, I'll probably redesign the database schema so these embedded subdocuments will be their own documents with just ObjectID reference to "parent" document.
Some resources:
https://docs.mongodb.com/manual/reference/operator/update/positional/
https://mongoosejs.com/docs/api.html#query_Query-findOneAndUpdate
I have a high-concurrency and parallelism situation and would like _id fields to be created by MongoDB and not by mongoose, so that I can use the ObjectId timestamps in the _id field to reliably query documents in the order they were inserted.
Is this possible? Right now I don't see how to do this with mongoose, as marking a schema with {_id: false} and trying to save it returns an error document must have an _id before saving.
Mongoose docs say the _id option only works on subdocuments, hence the error you get (http://mongoosejs.com/docs/guide.html#_id).
It might fit your situation to add a document without mongoose and in a subsequent operation update it through using mongoose (thereby keeping mongoose's Schema functionality etc).
using this line :
var collection = mongoose.connection.db.collection("users");
I get users s collection, now i need to get the schema from that collection ?
Is there a way to do this? thank you.
PS: I dont have any models
if you do not have any models, I'm afraid this can't be done.
the schema is the structural representation of the document, not the collection. You can use the schema (via the model) to enforce that any document added to the collection match some structure, but there's nothing that prevents you from inserting into this collection a different document without this model, that will not match the criteria
so the schema does not live in the DB, it is a part of the mongoose module, and lives in the code. and the way to access it is through the model only
I'm having trouble understanding with MongoDB is doing with my documents. I have a collection of a certain document. This document has a schema (I'm using Node.js Mongoose server-side). It has a couple of arrays of sub-documents. When I save a document that does not have an _id field Mongo should generate an _id field which it does. However, some of my 'sub-documents' also seem to have been given an _id field and other types of custom sub-documents were not. What the heck is going on here? Shouldn't I just get one _id per document?
I have Mongoose schema and I need to add a non-persistent field to it. The point of this field is to store some status, related to persistent data fields, but without need to store it to the database. I see that some Mongoose alternatives provide such a feature e.g. https://github.com/simpleviewinc/mongolayer#modeladdfieldargs, however I am not able to find similar one inside Mongoose.
Any tip would be greatly appreciated!
In mongoose you have the concept of virtual fields. See doc (http://mongoosejs.com/docs/guide.html#virtuals).
See also related topic at Adding 'virtual' variables to a mongoose schema?