types(schema): avoid treating paths with default: null as required

scripts/tsc-diagnostics-check.js

@@ -3,7 +3,7 @@
 const fs = require('fs');
 
 const stdin = fs.readFileSync(0).toString('utf8');
-const maxInstantiations = isNaN(process.argv[2]) ? 300000 : parseInt(process.argv[2], 10);
+const maxInstantiations = isNaN(process.argv[2]) ? 350000 : parseInt(process.argv[2], 10);
 
 console.log(stdin);
 

test/types/schema.test.ts

@@ -1999,3 +1999,20 @@ function autoInferredNestedMaps() {
   const doc = new TestModel({ nestedMap: new Map([['1', new Map([['2', 'value']])]]) });
   expectType<Map<string, Map<string, string>>>(doc.nestedMap);
 }
+
+function gh15878() {
+  const schema = new Schema({
+    name: {
+      type: String,
+      default: null
+    },
+    age: {
+      type: Number,
+      default: () => null
+    }
+  });
+  const TestModel = model('Test', schema);
+  const doc = new TestModel({ name: 'John', age: 30 });
+  expectType<string | null | undefined>(doc.name);
+  expectType<number | null | undefined>(doc.age);
+}

types/inferrawdoctype.d.ts

@@ -97,7 +97,7 @@ declare module 'mongoose' {
       ResolveRawPathType<Options['of'] extends ReadonlyArray<infer Item> ? Item : never>
     : PathValueType extends ArrayConstructor ? any[]
     : PathValueType extends typeof Schema.Types.Mixed ? any
-    : IfEquals<PathValueType, ObjectConstructor> extends true ? any
+    : PathValueType extends ObjectConstructor ? any
     : IfEquals<PathValueType, {}> extends true ? any
     : PathValueType extends typeof SchemaType ? PathValueType['prototype']
     : PathValueType extends Record<string, any> ? InferRawDocType<PathValueType>

types/inferschematype.d.ts

@@ -127,11 +127,6 @@ declare module 'mongoose' {
     : T;
 }
 
-type IsPathDefaultUndefined<PathType> =
-  PathType extends { default: undefined } ? true
-  : PathType extends { default: (...args: any[]) => undefined } ? true
-  : false;
-
 type RequiredPropertyDefinition =
   | {
       required: true | string | [true, string | undefined] | { isRequired: true };
@@ -150,16 +145,17 @@ type IsPathRequired<P, TypeKey extends string = DefaultTypeKey> =
     P extends { required: false } ?
       false
     : true
-  : P extends Record<TypeKey, ArrayConstructor | any[]> ?
-    IsPathDefaultUndefined<P> extends true ?
-      false
-    : true
-  : P extends Record<TypeKey, any> ?
-    P extends { default: any } ?
-      IfEquals<P['default'], undefined, false, true>
-    : false
+  : P extends { default: undefined | null | ((...args: any[]) => undefined) | ((...args: any[]) => null) } ? false
+  : P extends { default: any } ? true
+  : P extends Record<TypeKey, ArrayConstructor | any[]> ? true
   : false;
 
+// Internal type used to efficiently check for never or any types
+// can be efficiently checked like:
+// `[T] extends [neverOrAny] ? T : ...`
+// to avoid edge cases
+type neverOrAny = ' ~neverOrAny~';
+
 /**
  * @summary A Utility to obtain schema's required path keys.
  * @param {T} T A generic refers to document definition.
@@ -238,6 +234,7 @@ type PathEnumOrString<T extends SchemaTypeOptions<string>['enum']> =
 
 type IsSchemaTypeFromBuiltinClass<T> =
   T extends typeof String ? true
+  : unknown extends Buffer ? false
   : T extends typeof Number ? true
   : T extends typeof Boolean ? true
   : T extends typeof Buffer ? true
@@ -254,7 +251,6 @@ type IsSchemaTypeFromBuiltinClass<T> =
   : T extends Types.Decimal128 ? true
   : T extends NativeDate ? true
   : T extends typeof Schema.Types.Mixed ? true
-  : unknown extends Buffer ? false
   : T extends Buffer ? true
   : false;
 
@@ -270,12 +266,10 @@ type ResolvePathType<
   Options extends SchemaTypeOptions<PathValueType> = {},
   TypeKey extends string = DefaultSchemaOptions['typeKey'],
   TypeHint = never
-> = IfEquals<
-  TypeHint,
-  never,
-  PathValueType extends Schema ? InferSchemaType<PathValueType>
+> = [TypeHint] extends [never]
+  ? PathValueType extends Schema ? InferSchemaType<PathValueType>
   : PathValueType extends AnyArray<infer Item> ?
-    IfEquals<Item, never> extends true
+    [Item] extends [never]
       ? any[]
       : Item extends Schema ?
         // If Item is a schema, infer its type.
@@ -314,7 +308,7 @@ type ResolvePathType<
     : never
   : PathValueType extends ArrayConstructor ? any[]
   : PathValueType extends typeof Schema.Types.Mixed ? any
-  : IfEquals<PathValueType, ObjectConstructor> extends true ? any
+  : PathValueType extends ObjectConstructor ? any
   : IfEquals<PathValueType, {}> extends true ? any
   : PathValueType extends typeof SchemaType ? PathValueType['prototype']
   : PathValueType extends Record<string, any> ?
@@ -325,6 +319,5 @@ type ResolvePathType<
         typeKey: TypeKey;
       }
     >
-  : unknown,
-  TypeHint
->;
+  : unknown
+  : TypeHint;

types/virtuals.d.ts

@@ -8,7 +8,7 @@ declare module 'mongoose' {
   type TVirtualPathFN<DocType = {}, PathType = unknown, TInstanceMethods = {}, TReturn = unknown> =
     <T = HydratedDocument<DocType, TInstanceMethods>>(this: Document<any, any, DocType> & DocType, value: PathType, virtual: VirtualType<T>, doc: Document<any, any, DocType> & DocType) => TReturn;
 
-    type SchemaOptionsVirtualsPropertyType<DocType = any, VirtualPaths = Record<any, unknown>, TInstanceMethods = {}> = {
-      [K in keyof VirtualPaths]: VirtualPathFunctions<IsItRecordAndNotAny<DocType> extends true ? DocType : any, VirtualPaths[K], TInstanceMethods>
-    };
+  type SchemaOptionsVirtualsPropertyType<DocType = any, VirtualPaths = Record<any, unknown>, TInstanceMethods = {}> = {
+    [K in keyof VirtualPaths]: VirtualPathFunctions<IsItRecordAndNotAny<DocType> extends true ? DocType : any, VirtualPaths[K], TInstanceMethods>
+  };
 }