Schemas in separate project with arrays causes "Schema for array path is from a different copy of the Mongoose module."

[rndfm]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Mongoose version

7.0.3

Node.js version

18.13.0

MongoDB server version

6.0.5

Typescript version (if applicable)

No response

Description

I have my schemas defined in a separate npm package as they are going to be used be at couple of different services.

When using an array path in the first level i get the following error:
"TypeError: Schema for array path products is from a different copy of the Mongoose module. Please make sure you're using the same version of Mongoose everywhere with npm list mongoose. If you are still getting this error, please add new Schema() around the path: products: new Schema(...)"

I tried adding the new Scheme(..) thing. This makes the error message disappear but when i try to new up the model it fails there instead.

BUT. If i comment out the "if and throw" in schema.js: 1276, it works as expected.

The strange thing is. I have another array that works without any errors. But it's on "level 2". Eg. there's another object path before it.

My schema is quite simple:

import { Schema } from "mongoose";
import productSchema from "./Product.js";

const companySchema = new Schema({
	id: String,
	name: String,
	image: String,
	products: [new Schema(productSchema)]
});

export default companySchema;

import { Schema } from 'mongoose';

const productSchema = new Schema({
	id: String,
	name: String
});

export default productSchema;

If i change products to a single(non array) item in the company it works just fine.

My more complex scenario that actually works is a three level deep subDocument.

First level:

import { Schema } from "mongoose";
import consumptionDataSchema from "./ConsumptionData.js";

const userSchema = new Schema({
	name: String,
	email: String,
	image: String,
	consumptionData: consumptionDataSchema
});

export default userSchema;

Second level:

import { Schema } from "mongoose";
import meteringPointSchema from "./MeteringPoint.js";

const consumptionDataSchema = new Schema({
	authorized: Boolean,
	meteringPoints: [meteringPointSchema]
});

export default consumptionDataSchema;

Third level:

import { Schema } from "mongoose";

const meteringPointSchema = new Schema({
	id: String,
	type: String,
	name: String,
	rawData: Object
});

export default meteringPointSchema;

In my shared/common package I am listing mongoose as peerDependency.

All the packages has mongoose version 7.0.3

Steps to Reproduce

I have created a demo repo that shows the problem:

https://github.com/rndfm/mongoose-schema-error

Try and run the apps with:
node level1app.js
node level2app.js

For the level 1 app I get the following error:

PS C:\repos\mongoose-schema-error\app> node app.js
C:\repos\mongoose-schema-error\app\node_modules\mongoose\lib\schema.js:1277
        throw new TypeError('Schema for array path `' + path +
              ^

TypeError: Schema for array path `products` is from a different copy of the Mongoose module. Please make sure you're using the same version of Mongoose everywhere with `npm list mongoose`. If you are still getting this error, please add `new Schema()` around the path: products: new Schema(...)
    at Schema.interpretAsType (C:\repos\mongoose-schema-error\app\node_modules\mongoose\lib\schema.js:1277:15)
    at Schema.path (C:\repos\mongoose-schema-error\app\node_modules\mongoose\lib\schema.js:1033:27)
    at Schema.add (C:\repos\mongoose-schema-error\app\node_modules\mongoose\lib\schema.js:697:12)
    at merge (C:\repos\mongoose-schema-error\app\node_modules\mongoose\lib\helpers\schema\merge.js:12:6)
    at Schema.add (C:\repos\mongoose-schema-error\app\node_modules\mongoose\lib\schema.js:628:5)
    at new Schema (C:\repos\mongoose-schema-error\app\node_modules\mongoose\lib\schema.js:134:10)
    at Mongoose.model (C:\repos\mongoose-schema-error\app\node_modules\mongoose\lib\index.js:538:14)    at file:///C:/repos/mongoose-schema-error/app/app.js:7:1
    at ModuleJob.run (node:internal/modules/esm/module_job:194:25)

Node.js v18.13.0

For the level 2 app it works just fine.

Expected Behavior

I would expect this to work just the same in any level of the schema tree and not throw any errors.

[IslandRhythms]

Since you've updated since you posted the issue, what error are you seeing, what command are you running?

[rndfm]

Running the level1 and level2 apps in the demo repo should show the problem.
node level1app.js does not work. But it should.
node level2app.js works for me.

I updated the original issues and the demo repo to be more clear.

[IslandRhythms]

This is the error I get

[rndfm]

This is the error I get

What version of Node is that?
I just tried to clone the repo and run it with node version 18.13.0. And et runs fine. (Apart from the mongoose error)

I just added a very short readme

[rndfm]

I tried to change the way i import mongoose types. Maybe this is more compatible?

Pull :)

[vkarpov15]

The repro script you posted doesn't have a separate package for "shared", "shared" is a separate directory with Mongoose listed as a peerDependency. That setup won't work, "shared" isn't installed by npm so nothing will resolve its peer dependencies.

What's the output of npm list mongoose in your project?

[rndfm]

All I'm trying to do is reuse some schemas across two or more projects. What would be the right way to do this?

[rndfm]

And by the way. It works as expected when i comment out the line where the exception is thrown.

mongoose-schema-error\app\node_modules\mongoose\lib\schema.js:1277

[vkarpov15]

Depends on how your project is structured. In the setup in this repo: https://github.com/rndfm/mongoose-schema-error where you have multiple sibling directories, each with their own copy of Mongoose, I'd recommend either:

1. Add a top-level node_modules directory and put Mongoose as a dependency there. That way both app and shared use the top-level mongoose package.
2. Make shared only export the schema definition, not a Mongoose schema instance. So product.js exports { name: String } rather than new mongoose.Schema({ name: String }), company.js exports { products: [{ type: productSchemaDefinition }] } rather than { products: [productSchema] }. Export POJO, call new Schema() on that POJO.

The problems with multiple copies of the Mongoose modules are 1) incompatibilities between versions, and 2) any instanceof checks we use will break. So while your code may look like it works, we don't have tests in place to cover multi-module setups, so we're not as confident that Mongoose will work as designed in that case. That being said, we'll do some work to allow copying using new Schema() as the error message recommends.