Merge pull request #12870 from JavaScriptBach/const-array

Correctly infer string enums on const arrays

Author: vkarpov15

test/types/schema.test.ts

@@ -998,3 +998,23 @@ function gh12782() {
 function gh12816() {
   const schema = new Schema({}, { overwriteModels: true });
 }
+
+function gh12869() {
+  const dbExampleConst = new Schema(
+    {
+      active: { type: String, enum: ['foo', 'bar'] as const, required: true }
+    }
+  );
+
+  type ExampleConst = InferSchemaType<typeof dbExampleConst>;
+  expectType<'foo' | 'bar'>({} as ExampleConst['active']);
+
+  const dbExample = new Schema(
+    {
+      active: { type: String, enum: ['foo', 'bar'], required: true }
+    }
+  );
+
+  type Example = InferSchemaType<typeof dbExample>;
+  expectType<'foo' | 'bar'>({} as Example['active']);
+}

types/inferschematype.d.ts

@@ -168,7 +168,7 @@ type ObtainDocumentPathType<PathValueType, TypeKey extends string = DefaultTypeK
  * @param {T} T A generic refers to string path enums.
  * @returns Path enum values type as literal strings or string.
  */
-type PathEnumOrString<T extends SchemaTypeOptions<string>['enum']> = T extends (infer E)[] ? E : T extends { values: any } ? PathEnumOrString<T['values']> : string;
+type PathEnumOrString<T extends SchemaTypeOptions<string>['enum']> = T extends ReadonlyArray<infer E> ? E : T extends { values: any } ? PathEnumOrString<T['values']> : string;
 
 /**
  * @summary Resolve path type by returning the corresponding type.