types: cast primitive types within unions when applying create casting

[vkarpov15]

Fix #16316

Summary

PopulatedDoc is a union of an object type and a TreatAsPrimitives type. create() parameter casting needs to handle both the object type and the primitive type.

Examples

[Copilot]

Pull request overview

Adjusts Mongoose’s TypeScript Model#create() input casting types so union fields that include “primitive-ish” types (notably Types.ObjectId via PopulatedDoc) also accept the corresponding castable primitives (like string) during create casting. This addresses the reported regression where PopulatedDoc<User> could not accept a string id when creating documents.

Changes:

• Extend ApplyBasicCreateCasting<T> to include QueryTypeCasting for the TreatAsPrimitives portion of union-typed properties (fixing PopulatedDoc-style unions).
• Add a type test ensuring create() accepts string for a PopulatedDoc<User> ref field.

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated no comments.

File	Description
types/models.d.ts	Updates create-casting mapped type to allow primitive casting for the TreatAsPrimitives part of union-typed fields (e.g., allowing string for ObjectId in PopulatedDoc).
test/types/create.test.ts	Adds a type-level test case covering Model#create() with a PopulatedDoc ref field accepting a string id.