types: pass DocType down to subdocuments so `HydratedSingleSubdocumen…

…t` and `HydratedArraySubdocument` `toObject()` returns correct type

Fix #14601

test/types/subdocuments.test.ts

@@ -1,4 +1,13 @@
-import { Schema, model, Model, Document, Types } from 'mongoose';
+import {
+  Schema,
+  model,
+  Model,
+  Document,
+  Types,
+  HydratedArraySubdocument,
+  HydratedSingleSubdocument
+} from 'mongoose';
+import { expectAssignable } from 'tsd';
 
 const childSchema: Schema = new Schema({ name: String });
 
@@ -108,3 +117,35 @@ function gh13040(): void {
     product.ownerDocument();
   });
 }
+
+function gh14601() {
+  interface ISub {
+    field1: string;
+  }
+  interface IMain {
+    f1: string;
+    f2: HydratedSingleSubdocument<ISub>;
+    f3: HydratedArraySubdocument<ISub>[];
+  }
+
+  const subSchema = new Schema({ field1: String }, { _id: false });
+
+  const mainSchema = new Schema({
+    f1: String,
+    f2: { type: subSchema },
+    f3: { type: [subSchema] }
+  });
+  const MainModel = model<IMain>('Main', mainSchema);
+
+  const item = new MainModel({
+    f1: 'test',
+    f2: { field1: 'test' },
+    f3: [{ field1: 'test' }]
+  });
+
+  const obj = item.toObject();
+
+  const obj2 = item.f2.toObject();
+
+  expectAssignable<{ _id: Types.ObjectId, field1: string }>(obj2);
+}

types/index.d.ts

@@ -153,8 +153,8 @@ declare module 'mongoose' {
         >
       >
   >;
-  export type HydratedSingleSubdocument<DocType, TOverrides = {}> = Types.Subdocument<unknown> & Require_id<DocType> & TOverrides;
-  export type HydratedArraySubdocument<DocType, TOverrides = {}> = Types.ArraySubdocument<unknown> & Require_id<DocType> & TOverrides;
+  export type HydratedSingleSubdocument<DocType, TOverrides = {}> = Types.Subdocument<unknown, Record<string, never>, DocType> & Require_id<DocType> & TOverrides;
+  export type HydratedArraySubdocument<DocType, TOverrides = {}> = Types.ArraySubdocument<unknown, Record<string, never>, DocType> & Require_id<DocType> & TOverrides;
 
   export type HydratedDocumentFromSchema<TSchema extends Schema> = HydratedDocument<
   InferSchemaType<TSchema>,

types/types.d.ts

@@ -95,7 +95,7 @@ declare module 'mongoose' {
       $parent(): Document;
     }
 
-    class ArraySubdocument<IdType = any> extends Subdocument<IdType> {
+    class ArraySubdocument<IdType = any, TQueryHelpers = unknown, DocType = unknown> extends Subdocument<IdType, TQueryHelpers, DocType> {
       /** Returns this sub-documents parent array. */
       parentArray(): Types.DocumentArray<unknown>;
     }