recursively convert buffer to binary

Author: vkarpov15

test/types/schema.test.ts

@@ -1667,12 +1667,17 @@ async function gh14950() {
 }
 
 async function gh14902() {
-  const def = {
-    image: { type: Buffer }
-  } as const;
-  const exampleSchema = new Schema(def);
+  const exampleSchema = new Schema({
+    image: { type: Buffer },
+    subdoc: {
+      type: new Schema({
+        testBuf: Buffer
+      })
+    }
+  });
   const Test = model('Test', exampleSchema);
 
   const doc = await Test.findOne().lean().orFail();
   expectType<Binary | null | undefined>(doc.image);
+  expectType<Binary | null | undefined>(doc.subdoc!.testBuf);
 }

types/index.d.ts

@@ -706,12 +706,16 @@ declare module 'mongoose' {
     [K in keyof T]: FlattenProperty<T[K]>;
   };
 
-  export type BufferToBinary<T> = T extends object ? {
+  export type BufferToBinary<T> = T extends TreatAsPrimitives ? T : T extends Record<string, any> ? {
     [K in keyof T]: T[K] extends Buffer
       ? mongodb.Binary
       : T[K] extends (Buffer | null | undefined)
         ? mongodb.Binary | null | undefined
-        : T[K];
+        : T[K] extends Types.DocumentArray<infer ItemType>
+            ? Types.DocumentArray<BufferToBinary<ItemType>>
+            : T[K] extends Types.Subdocument<unknown, unknown, infer SubdocType>
+              ? HydratedSingleSubdocument<SubdocType>
+              : BufferToBinary<T[K]>;
   } : T;
 
   /**

types/query.d.ts

@@ -211,7 +211,7 @@ declare module 'mongoose' {
   type QueryOpThatReturnsDocument = 'find' | 'findOne' | 'findOneAndUpdate' | 'findOneAndReplace' | 'findOneAndDelete';
 
   type GetLeanResultType<RawDocType, ResultType, QueryOp> = QueryOp extends QueryOpThatReturnsDocument
-    ? (ResultType extends any[] ? Require_id<FlattenMaps<BufferToBinary<RawDocType>>>[] : Require_id<FlattenMaps<BufferToBinary<RawDocType>>>)
+    ? (ResultType extends any[] ? Require_id<BufferToBinary<FlattenMaps<RawDocType>>>[] : Require_id<BufferToBinary<FlattenMaps<RawDocType>>>)
     : ResultType;
 
   type MergePopulatePaths<RawDocType, ResultType, QueryOp, Paths, TQueryHelpers, TInstanceMethods = Record<string, never>> = QueryOp extends QueryOpThatReturnsDocument