fix(types): avoid treating | undefined types as any in `Require_i…

…d` to better support `_id: String` with auto-typed schemas

Fix #12070

test/types/models.test.ts

@@ -1,5 +1,14 @@
 import { ObjectId } from 'bson';
-import { Schema, Document, Model, connection, model, Types, UpdateQuery, CallbackError } from 'mongoose';
+import {
+  Schema,
+  Document,
+  Model,
+  connection,
+  model,
+  Types,
+  UpdateQuery,
+  CallbackError
+} from 'mongoose';
 import { expectAssignable, expectError, expectType } from 'tsd';
 import { AutoTypedSchemaType, autoTypedSchema } from './schema.test';
 import { UpdateOneModel } from 'mongodb';
@@ -328,3 +337,11 @@ function gh12100() {
   Model.syncIndexes({ continueOnError: true, noResponse: true });
   Model.syncIndexes({ continueOnError: false, noResponse: true });
 }
+
+(function gh12070() {
+  const schema_with_string_id = new Schema({ _id: String, nickname: String });
+  const TestModel = model('test', schema_with_string_id);
+  const obj = new TestModel();
+
+  expectType<string>(obj._id);
+})();

types/index.d.ts

@@ -109,9 +109,7 @@ declare module 'mongoose' {
   }
 
   export type Require_id<T> = T extends { _id?: infer U }
-    ? U extends any
-      ? (T & { _id: Types.ObjectId })
-      : T & Required<{ _id: U }>
+    ? IfAny<U, T & { _id: Types.ObjectId }, T & Required<{ _id: U }>>
     : T & { _id: Types.ObjectId };
 
   export type RequireOnlyTypedId<T> = T extends { _id?: infer U; }
@@ -539,7 +537,7 @@ declare module 'mongoose' {
   export type SchemaDefinitionType<T> = T extends Document ? Omit<T, Exclude<keyof Document, '_id' | 'id' | '__v'>> : T;
 
   // Helpers to simplify checks
-  type IfAny<IFTYPE, THENTYPE> = 0 extends (1 & IFTYPE) ? THENTYPE : IFTYPE;
+  type IfAny<IFTYPE, THENTYPE, ELSETYPE = IFTYPE> = 0 extends (1 & IFTYPE) ? THENTYPE : ELSETYPE;
   type IfUnknown<IFTYPE, THENTYPE> = unknown extends IFTYPE ? THENTYPE : IFTYPE;
 
   // tests for these two types are located in test/types/lean.test.ts