Add inferRawDocType helper

docs/typescript/schemas.md

@@ -9,7 +9,7 @@ Mongoose can automatically infer the document type from your schema definition a
 We recommend relying on automatic type inference when defining schemas and models.
 
 ```typescript
-import { Schema } from 'mongoose';
+import { Schema, model } from 'mongoose';
 // Schema
 const schema = new Schema({
   name: { type: String, required: true },
@@ -32,6 +32,31 @@ There are a few caveats for using automatic type inference:
 2. You need to define your schema in the `new Schema()` call. Don't assign your schema definition to a temporary variable. Doing something like `const schemaDefinition = { name: String }; const schema = new Schema(schemaDefinition);` will not work.
 3. Mongoose adds `createdAt` and `updatedAt` to your schema if you specify the `timestamps` option in your schema, *except* if you also specify `methods`, `virtuals`, or `statics`. There is a [known issue](https://github.com/Automattic/mongoose/issues/12807) with type inference with timestamps and methods/virtuals/statics options. If you use methods, virtuals, and statics, you're responsible for adding `createdAt` and `updatedAt` to your schema definition.
 
+If you need to explicitly get the raw document type (the value returned from `doc.toObject()`, `await Model.findOne().lean()`, etc.) from your schema definition, you can use Mongoose's `inferRawDocType` helper as follows:
+
+```ts
+import { Schema, InferRawDocType, model } from 'mongoose';
+
+const schemaDefinition = {
+  name: { type: String, required: true },
+  email: { type: String, required: true },
+  avatar: String
+} as const;
+const schema = new Schema(schemaDefinition);
+
+const UserModel = model('User', schema);
+const doc = new UserModel({ name: 'test', email: 'test' });
+
+type RawUserDocument = InferRawDocType<typeof schemaDefinition>;
+
+useRawDoc(doc.toObject());
+
+function useRawDoc(doc: RawUserDocument) {
+  // ...
+}
+
+```
+
 If automatic type inference doesn't work for you, you can always fall back to document interface definitions.
 
 ## Separate document interface definition

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]) ? 125000 : parseInt(process.argv[2], 10);
+const maxInstantiations = isNaN(process.argv[2]) ? 127500 : parseInt(process.argv[2], 10);
 
 console.log(stdin);
 

test/types/schema.test.ts

@@ -6,6 +6,7 @@ import {
   HydratedDocument,
   IndexDefinition,
   IndexOptions,
+  InferRawDocType,
   InferSchemaType,
   InsertManyOptions,
   ObtainDocumentType,
@@ -1494,3 +1495,19 @@ function gh14573() {
   const doc = new UserModel({ names: { _id: '0'.repeat(24), firstName: 'foo' } });
   doc.names?.ownerDocument();
 }
+
+function gh13772() {
+  const schemaDefinition = {
+    name: String,
+    docArr: [{ name: String }]
+  };
+  const schema = new Schema(schemaDefinition);
+  type RawDocType = InferRawDocType<typeof schemaDefinition>;
+  expectAssignable<
+    { name?: string | null, docArr?: Array<{ name?: string | null }> }
+  >({} as RawDocType);
+
+  const TestModel = model('User', schema);
+  const doc = new TestModel();
+  expectAssignable<RawDocType>(doc.toObject());
+}

types/index.d.ts

@@ -20,6 +20,7 @@
 /// <reference path="./types.d.ts" />
 /// <reference path="./utility.d.ts" />
 /// <reference path="./validation.d.ts" />
+/// <reference path="./inferrawdoctype.d.ts" />
 /// <reference path="./inferschematype.d.ts" />
 /// <reference path="./virtuals.d.ts" />
 /// <reference path="./augmentations.d.ts" />

types/inferrawdoctype.d.ts

@@ -0,0 +1,116 @@
+import {
+  IsSchemaTypeFromBuiltinClass,
+  RequiredPaths,
+  OptionalPaths,
+  PathWithTypePropertyBaseType,
+  PathEnumOrString
+} from './inferschematype';
+
+declare module 'mongoose' {
+  export type InferRawDocType<
+    DocDefinition,
+    TSchemaOptions extends Record<any, any> = DefaultSchemaOptions
+  > = {
+    [
+    K in keyof (RequiredPaths<DocDefinition, TSchemaOptions['typeKey']> &
+    OptionalPaths<DocDefinition, TSchemaOptions['typeKey']>)
+    ]: ObtainRawDocumentPathType<DocDefinition[K], TSchemaOptions['typeKey']>;
+  };
+
+  /**
+   * @summary Obtains schema Path type.
+   * @description Obtains Path type by separating path type from other options and calling {@link ResolvePathType}
+   * @param {PathValueType} PathValueType Document definition path type.
+   * @param {TypeKey} TypeKey A generic refers to document definition.
+   */
+  type ObtainRawDocumentPathType<
+    PathValueType,
+    TypeKey extends string = DefaultTypeKey
+  > = ResolveRawPathType<
+    PathValueType extends PathWithTypePropertyBaseType<TypeKey> ? PathValueType[TypeKey] : PathValueType,
+    PathValueType extends PathWithTypePropertyBaseType<TypeKey> ? Omit<PathValueType, TypeKey> : {},
+    TypeKey
+  >;
+
+  /**
+   * Same as inferSchemaType, except:
+   *
+   * 1. Replace `Types.DocumentArray` and `Types.Array` with vanilla `Array`
+   * 2. Replace `ObtainDocumentPathType` with `ObtainRawDocumentPathType`
+   * 3. Replace `ResolvePathType` with `ResolveRawPathType`
+   *
+   * @summary Resolve path type by returning the corresponding type.
+   * @param {PathValueType} PathValueType Document definition path type.
+   * @param {Options} Options Document definition path options except path type.
+   * @param {TypeKey} TypeKey A generic of literal string type."Refers to the property used for path type definition".
+   * @returns Number, "Number" or "number" will be resolved to number type.
+   */
+  type ResolveRawPathType<PathValueType, Options extends SchemaTypeOptions<PathValueType> = {}, TypeKey extends string = DefaultSchemaOptions['typeKey']> =
+  PathValueType extends Schema ?
+    InferSchemaType<PathValueType> :
+    PathValueType extends (infer Item)[] ?
+      IfEquals<Item, never, any[], Item extends Schema ?
+        // If Item is a schema, infer its type.
+        Array<InferSchemaType<Item>> :
+        Item extends Record<TypeKey, any> ?
+          Item[TypeKey] extends Function | String ?
+            // If Item has a type key that's a string or a callable, it must be a scalar,
+            // so we can directly obtain its path type.
+            ObtainRawDocumentPathType<Item, TypeKey>[] :
+            // If the type key isn't callable, then this is an array of objects, in which case
+            // we need to call ObtainDocumentType to correctly infer its type.
+            Array<ObtainDocumentType<Item, any, { typeKey: TypeKey }>> :
+          IsSchemaTypeFromBuiltinClass<Item> extends true ?
+            ObtainRawDocumentPathType<Item, TypeKey>[] :
+            IsItRecordAndNotAny<Item> extends true ?
+              Item extends Record<string, never> ?
+                ObtainRawDocumentPathType<Item, TypeKey>[] :
+                Array<ObtainDocumentType<Item, any, { typeKey: TypeKey }>> :
+              ObtainRawDocumentPathType<Item, TypeKey>[]
+      >:
+      PathValueType extends ReadonlyArray<infer Item> ?
+        IfEquals<Item, never, any[], Item extends Schema ?
+          Array<InferSchemaType<Item>> :
+          Item extends Record<TypeKey, any> ?
+            Item[TypeKey] extends Function | String ?
+              ObtainRawDocumentPathType<Item, TypeKey>[] :
+              ObtainDocumentType<Item, any, { typeKey: TypeKey }>[]:
+            IsSchemaTypeFromBuiltinClass<Item> extends true ?
+              ObtainRawDocumentPathType<Item, TypeKey>[] :
+              IsItRecordAndNotAny<Item> extends true ?
+                Item extends Record<string, never> ?
+                  ObtainRawDocumentPathType<Item, TypeKey>[] :
+                  Array<ObtainDocumentType<Item, any, { typeKey: TypeKey }>> :
+                ObtainRawDocumentPathType<Item, TypeKey>[]
+        >:
+        PathValueType extends StringSchemaDefinition ? PathEnumOrString<Options['enum']> :
+          IfEquals<PathValueType, Schema.Types.String> extends true ? PathEnumOrString<Options['enum']> :
+            IfEquals<PathValueType, String> extends true ? PathEnumOrString<Options['enum']> :
+              PathValueType extends NumberSchemaDefinition ? Options['enum'] extends ReadonlyArray<any> ? Options['enum'][number] : number :
+                IfEquals<PathValueType, Schema.Types.Number> extends true ? number :
+                  PathValueType extends DateSchemaDefinition ? Date :
+                    IfEquals<PathValueType, Schema.Types.Date> extends true ? Date :
+                      PathValueType extends typeof Buffer | 'buffer' | 'Buffer' | typeof Schema.Types.Buffer ? Buffer :
+                        PathValueType extends BooleanSchemaDefinition ? boolean :
+                          IfEquals<PathValueType, Schema.Types.Boolean> extends true ? boolean :
+                            PathValueType extends ObjectIdSchemaDefinition ? Types.ObjectId :
+                              IfEquals<PathValueType, Types.ObjectId> extends true ? Types.ObjectId :
+                                IfEquals<PathValueType, Schema.Types.ObjectId> extends true ? Types.ObjectId :
+                                  PathValueType extends 'decimal128' | 'Decimal128' | typeof Schema.Types.Decimal128 ? Types.Decimal128 :
+                                    IfEquals<PathValueType, Schema.Types.Decimal128> extends true ? Types.Decimal128 :
+                                      IfEquals<PathValueType, Types.Decimal128> extends true ? Types.Decimal128 :
+                                        IfEquals<PathValueType, Schema.Types.BigInt> extends true ? bigint :
+                                          IfEquals<PathValueType, BigInt> extends true ? bigint :
+                                            PathValueType extends 'bigint' | 'BigInt' | typeof Schema.Types.BigInt | typeof BigInt ? bigint :
+                                              PathValueType extends 'uuid' | 'UUID' | typeof Schema.Types.UUID ? Buffer :
+                                                IfEquals<PathValueType, Schema.Types.UUID> extends true ? Buffer :
+                                                  PathValueType extends MapConstructor | 'Map' ? Map<string, ResolveRawPathType<Options['of']>> :
+                                                    IfEquals<PathValueType, typeof Schema.Types.Map> extends true ? Map<string, ResolveRawPathType<Options['of']>> :
+                                                      PathValueType extends ArrayConstructor ? any[] :
+                                                        PathValueType extends typeof Schema.Types.Mixed ? any:
+                                                          IfEquals<PathValueType, ObjectConstructor> extends true ? any:
+                                                            IfEquals<PathValueType, {}> extends true ? any:
+                                                              PathValueType extends typeof SchemaType ? PathValueType['prototype'] :
+                                                                PathValueType extends Record<string, any> ? ObtainDocumentType<PathValueType, any, { typeKey: TypeKey }> :
+                                                                  unknown;
+}