Virtual entity custom filter query #5971
Description
Is your feature request related to a problem? Please describe.
The way EntityManager.find (and other methods) work, is that they infer the properties existing in the entity passed as the first value, and use its properties as a filter query in the second parameter.
This is a problem with virtual entities where some filters are needed that only appear in the query but don't end up in the entity.
For example something like:
@Entity({
expression: (em, where) => {
return em.aggregate(Book, [
{ $match: { genre: where.genre } },
{ $group: { _id: "$userId" } },
{ $lookup: { from: "user", localField: "_id", foreignField: "_id", as: "publisher" } },
{ $unwind: "$publisher" },
{ $replaceRoot: { newRoot: "$publisher" } }
]);
}
})
export class Publisher {
@Property()
public _id: ObjectId;
}In this example I'm trying to get users who have books using the virtual entity, and I need to query based on the genre field from the Book entity, but the genre isn't in the Publisher virtual entity. This will cause the following type error on genre:
const publishers = await em.find(Publisher, { genre: "non-fiction" });
^^^-> Object literal may only specify known properties, and 'genre' does not exist in type 'RegExp | ObjectId | ObjectQuery<Publisher> | NonNullable<EntityProps<Publisher> & OperatorMap<Publisher>> | FilterQuery<...>[]'.ts(2353)Describe the solution you'd like
I think one way to do it is to be able to override the FilterQuery<T> type using a symbol like you're already doing with OptionalProps and others.
So the usage will be:
@Entity
export class VirtualEntity {
public readonly [FilterQueryOverride]?: { genre: string };
// ...
}Now FilterQuery<VirtualEntity> should result in { genre: string }.
Describe alternatives you've considered
I don't have any other proper solutions for this issue. Please let me know if I'm missing something that can resolve this.
Additional context
I know we can override this by just casting the object as FilterQuery<T> or even any but I'm trying to suggest a solution that keeps the type safety and proper auto completions working.