[Typescript] Query types weirdness with ResultType, DocType and RawDocType generics

[hasezoey]

I am currently trying to fix typegoose/typegoose#870, but i got confused because of the 3 types mentioned in the title, for example:

Model.find({})'s return type is:

mongoose.Query<
    (mongoose.Document<
      unknown,
      {},
      {
        username?: string | undefined;
      }
    > & {
      username?: string | undefined;
    } & {
      _id: mongoose.Types.ObjectId;
    })[],
    mongoose.Document<
      unknown,
      {},
      {
        username?: string | undefined;
      }
    > & {
      username?: string | undefined;
    } & {
      _id: mongoose.Types.ObjectId;
    },
    {},
    {
      username?: string | undefined;
    },
    'find'
  >;

(basically Query<Document<>[], Document<>, {}, ActualRawObject, QueryOperation>)

but doing a additional .find (because it is possible and has the closest types to the query helpers) like Model.find({}).find({}) has actually the wrong typing for the suggestions in {} (for the second .find), because the second .find uses the DocType parameter of the Query<> type, but that is set to a Document<>, which makes it suggest function like populate as a value:

in addition, fixing it in typegoose by replacing the current mongoose.QueryWithHelpers<Document<>, Document<>> with mongoose.QueryWithHelpers<Document<>, RawClassType> actually breaks query helper functions which return this.find (and other functions) because those functions all return the generic DocType in the Query<>'s ResultType generic slot, instead of the ResultType generic. current code snippit:

// snippit from query.d.ts
find(
  filter: FilterQuery<DocType>,
  projection?: ProjectionType<DocType> | null,
  options?: QueryOptions<DocType> | null
): QueryWithHelpers<Array<DocType>, DocType, THelpers, RawDocType, 'find'>;

(notice the QueryWithHelpers<DocType[], DocType>)

where as the Model's functions return a ResultType in the ResultType generic slot, snippit:

// snippit from model.d.ts
find<ResultDoc = THydratedDocumentType>(
  filter: FilterQuery<TRawDocType>,
  projection?: ProjectionType<TRawDocType> | null | undefined,
  options?: QueryOptions<TRawDocType> | null | undefined
): QueryWithHelpers<Array<ResultDoc>, ResultDoc, TQueryHelpers, TRawDocType, 'find'>;

(notice the QueryWithHelpers<ResultDoc[], ResultDoc>)

---

so my question is: am i doing things wrong, or are the mongoose types wrong?

mongoose 1bfcdf6 and 8.0.0 (even in 7.6.4)

[vkarpov15]

At first glance it looks like Mongoose's types may be wrong. Maybe replace this:

// snippit from query.d.ts
find(
  filter: FilterQuery<DocType>,
  projection?: ProjectionType<DocType> | null,
  options?: QueryOptions<DocType> | null
): QueryWithHelpers<Array<DocType>, DocType, THelpers, RawDocType, 'find'>;

with this?

// snippit from query.d.ts
find(
  filter: FilterQuery<RawDocType>,
  projection?: ProjectionType<RawDocType> | null,
  options?: QueryOptions<DocType> | null
): QueryWithHelpers<Array<DocType>, DocType, THelpers, RawDocType, 'find'>;

You're right that find() filter param shouldn't type as a document.

[hasezoey]

that fixes it for the .find method, other methods will also need to be touched, in addition aside from the testing case i was working with (plain mongoose), in typegoose i also need to explicitly set Query's RawDocType generic now, because otherwise it defaults to DocType.

and to clarify, why do those methods return DocType[] as the ResultType instead of using the generic ResultType already available, or does .find overwrite something at runtime that i missed (like overwriting the previous call to .find)?
the .find should also likely have a generic itself to match the definition in model.d.ts (find<ResultDoc = THydratedDocumentType>), right?