[@types/mongodb] Generic TSchema type not accepted by insert methods

[g-pascal]

Hi, I'm trying to build a generic Typescript DAO on top of mongodb, but I can't figure if the typings are simply incompatible with generic TSchema types, or if I'm doing something wrong.

A simple example:

import { Collection, MongoClient, ObjectId } from 'mongodb';
export class AbstractDao<T extends { _id: ObjectId }> {
    private mongoClient: MongoClient;

    public async create(entity: T): Promise<void> {
        const collection: Collection<T> = this.mongoClient.db('test-db').collection('test-collection');

        // Argument of type 'T' is not assignable to parameter of type 'OptionalId<T>'.
        // Type '{ _id: ObjectId; }' is not assignable to type 'OptionalId<T>'.
        await collection.insertOne(entity);
    }
}

I'm expecting Collection.insertOne to accept entity, but I can't get T extends { _id: ObjectId } to be accepted as a valid OptionalId<T>. I tried various constraints for T but I never got this class to compile.

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[g-pascal]

So I've dug into it and it boils down to my T extends { _id: ObjectId } not being assignable to the OptionalId<TSchema> expected by Collection.insertOne, because OptionalId is defined as a conditional type, in which type constraints are not resolved because of a language limitation better explained in this typescript issue.

I'm not sure exactly what case the OptionalId type is meant to handle, I think it's trying to enforce that the type of the _id property of an OptionalId<TSchema> must either be typeof TSchema['_id'] if it exists, or ObjectId otherwise?

The previous definition of OptionalId (before the commit e19dc99) worked well with generic TSchema types, because it did not use a conditional type, so TSchema constraints were properly resolved. But it did not enforce any specific type for the _id property in OptionalId, so that's a tradeoff.

[CaselIT]

Since the issue in typescript seems to be by design I think we could revert the OptionalId definition to the previous one. Could you open a pr for it?

[HosseinAgha]

@CaselIT @g-pascal
Please also take look at this issue before merging anything: #39358
IMHO opening up the types for a special very abstract/generic use case usually results in more runtime bugs.

[dattannguyen]

Hi @HosseinAgha, I came here after reading #39358 and your issue on microsoft/TypeScript#35647, also microsoft/TypeScript#35077.

TypeScript said it works as expected so they have nothing to do, it brings the matter back to @types/mongodb. So now we just do workarounds, e.g {} as FilterQuery<Schema> or do you have any plan to fix in @types/mongodb?

[mariocalin]

Same here. Trying also to create a generic DAO.

[ravshansbox]

Experiencing the same problem. Any plans on resolving the issue?

[wuriyanto48]

try this

`collection.insertOne(entity as any);`

[adriana47]

Just ran into the same problem. Can't work without type safety in a strict codebase. Casting it as any or unknown is a dangerous and ugly workaround. The PR above has been abandoned, any chance of reopening?

[LinusU]

The @types/mongodb packages has been removed and typings are now shipped upstream as part of the mongodb package, so this issue can be closed...

[peterblazejewicz]

Closing as per last comment, thx!