fix types when selecting objects such as dates (#524)

Author: samwillis

.changeset/lucky-years-wish.md

@@ -0,0 +1,5 @@
+---
+"@tanstack/db": patch
+---
+
+Fix a bug where selecting a prop that used a built in object such as a Date would result in incorrect types in the result object.

packages/db/src/query/builder/types.ts

@@ -500,20 +500,20 @@ export type Ref<T = any> = {
   [K in keyof T]: IsNonExactOptional<T[K]> extends true
     ? IsNonExactNullable<T[K]> extends true
       ? // Both optional and nullable
-        NonNullable<T[K]> extends Record<string, any>
+        IsPlainObject<NonNullable<T[K]>> extends true
         ? Ref<NonNullable<T[K]>> | undefined
         : RefLeaf<NonNullable<T[K]>> | undefined
       : // Optional only
-        NonUndefined<T[K]> extends Record<string, any>
+        IsPlainObject<NonUndefined<T[K]>> extends true
         ? Ref<NonUndefined<T[K]>> | undefined
         : RefLeaf<NonUndefined<T[K]>> | undefined
     : IsNonExactNullable<T[K]> extends true
       ? // Nullable only
-        NonNull<T[K]> extends Record<string, any>
+        IsPlainObject<NonNull<T[K]>> extends true
         ? Ref<NonNull<T[K]>> | null
         : RefLeaf<NonNull<T[K]>> | null
       : // Required
-        T[K] extends Record<string, any>
+        IsPlainObject<T[K]> extends true
         ? Ref<T[K]>
         : RefLeaf<T[K]>
 } & RefLeaf<T>
@@ -825,3 +825,48 @@ export type WithResult<TContext extends Context, TResult> = Prettify<
 export type Prettify<T> = {
   [K in keyof T]: T[K]
 } & {}
+
+/**
+ * IsPlainObject - Utility type to check if T is a plain object
+ */
+type IsPlainObject<T> = T extends unknown
+  ? T extends object
+    ? T extends ReadonlyArray<any>
+      ? false
+      : T extends JsBuiltIns
+        ? false
+        : true
+    : false
+  : false
+
+/**
+ * JsBuiltIns - List of JavaScript built-ins
+ */
+type JsBuiltIns =
+  | ArrayBuffer
+  | ArrayBufferLike
+  | AsyncGenerator<any, any, any>
+  | BigInt64Array
+  | BigUint64Array
+  | DataView
+  | Date
+  | Error
+  | Float32Array
+  | Float64Array
+  // eslint-disable-next-line @typescript-eslint/no-unsafe-function-type
+  | Function
+  | Generator<any, any, any>
+  | Int16Array
+  | Int32Array
+  | Int8Array
+  | Map<any, any>
+  | Promise<any>
+  | RegExp
+  | Set<any>
+  | string
+  | Uint16Array
+  | Uint32Array
+  | Uint8Array
+  | Uint8ClampedArray
+  | WeakMap<any, any>
+  | WeakSet<any>

packages/db/tests/query/select.test-d.ts

@@ -7,6 +7,8 @@ import { upper } from "../../src/query/builder/functions.js"
 type User = {
   id: number
   name: string
+  joinedDate: Date
+  something: string
   profile: {
     bio: string
     preferences: {
@@ -53,6 +55,29 @@ describe(`select types`, () => {
     expectTypeOf(results).toEqualTypeOf<Expected>()
   })
 
+  test(`works with js built-ins objects`, () => {
+    const users = createUsers()
+    const col = createLiveQueryCollection((q) =>
+      q.from({ u: users }).select(({ u }) => ({
+        id: u.id,
+        joinedDate: u.joinedDate,
+        name: u.name,
+        something: u.something,
+      }))
+    )
+
+    type Expected = {
+      id: number
+      joinedDate: Date
+      name: string
+      something: string
+    }
+
+    const results = col.toArray[0]!
+
+    expectTypeOf(results).toEqualTypeOf<Expected>()
+  })
+
   test(`nested object selection infers nested result type`, () => {
     const users = createUsers()
     const col = createLiveQueryCollection((q) =>