Can't instance a model from mongoose after update from v4 to v6

[nestjs]

Can't instance a model from mongoose after update from v4 to v6

[igorivaniuk]

@NenadJovicic for now i doing something like this

export const getModel = name => {
  return mongoose.connections[1].model(name)
}

Schema.pre('save', function (next: Function): void {
   const someModel = getModel(modelName);
   someModel.countDocuments(query).then((result: number) => {
       return next(true);
   }).catch((error) => next(error));
});

[kamilmysliwiec]

Could you please provide a minimal repository which reproduces your issue? :)

[NenadJovicic]

https://github.com/NenadJovicic/test-nest-project
Here it is, minimal repo that will reproduce an issue
@kamilmysliwiec you just have to create some local db on your machine with users collection and maybe some data

[BorntraegerMarc]

@kamilmysliwiec did you have time to look into this?

[NenadJovicic]

still no update on this? @kamilmysliwiec

[NenadJovicic]

@igorivaniuk thanks for help

@kamilmysliwiec tested out also with mongoose 5.0.1, because I used that version with nest v4, and there is a same problem.
With nest v4 and mongoose 5.0.1 mongoose.connections array does not exist at all
So, looks like problem that we have is something about your engine and how it sets connections.

because default connection for mongoose that is set up does not contain all collections that my db has, only 1 collection, and 2nd connection from list of mongoose.connections actually contains all models and collections that are in my DB

[NenadJovicic]

@kamilmysliwiec I found a reason why is this happening, that we have 2 different connections with mongoose, and that 2nd one is only valid one, or connection to my DB.

It happened in this commit where you changed from mongoose.connect to mongoose.createConnection inside mongoose.core.module.ts
connect method was overriding previous connection, and createConnection is adding new connection to mongoose.connections array
What I don't understand is why 1st (not valid) connection is created. What I found out is, it calls createConnection immediately when I import MongooseModule in app.module.ts of my app
where uri for connection and options are undefined.

So, is there any way to fix this? To not add that first default connection on import or to return it to connect method

[kamilmysliwiec]

You can inject the Connection into your class (see here https://docs.nestjs.com/techniques/mongodb#connection) and dynamically call model.

[kamalkech]

const someModel = mongoose.model(EventModel.name, EventSchema);
TypeError: Cannot read property 'model' of undefined

[jmcdo29]

const someModel = mongoose.model(EventModel.name, EventSchema); TypeError: Cannot read property 'model' of undefined

If I had to bet, it has to deal with how you import mongoose. Try a named import like import * as mongoose from 'mongoose'
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