From 07b33771e3315a2aa77dad40348f27c72ec58f55 Mon Sep 17 00:00:00 2001
From: LeCarbonator <18158911+LeCarbonator@users.noreply.github.com>
Date: Thu, 5 Jun 2025 18:03:28 +0200
Subject: [PATCH] fix(form-core): fix DeepValue from record values being wrong

---
 packages/form-core/src/util-types.ts          | 35 ++++++++++++------
 packages/form-core/tests/util-types.test-d.ts | 36 +++++++++++++++++++
 2 files changed, 60 insertions(+), 11 deletions(-)

diff --git a/packages/form-core/src/util-types.ts b/packages/form-core/src/util-types.ts
index 4049e1cbe..9aa71ee57 100644
--- a/packages/form-core/src/util-types.ts
+++ b/packages/form-core/src/util-types.ts
@@ -150,8 +150,18 @@ export type DeepKeysAndValuesImpl<
             ? DeepKeyAndValueObject<TParent, T, TAcc>
             : TAcc
 
-export type DeepRecord<T> = {
-  [TRecord in DeepKeysAndValues<T> as TRecord['key']]: TRecord['value']
+type DeepRecordWithDynamicSuffix<T> = {
+  // DeepKeys uses a dot as reserved character, so the only way that it can be a suffix
+  // is if the suffix is a dynamic variable.
+  [TRecord in DeepKeysAndValues<T> as `${TRecord['key']}.` extends TRecord['key']
+    ? TRecord['key']
+    : never]: TRecord['value']
+}
+
+type DeepRecordWithStaticSuffix<T> = {
+  [TRecord in DeepKeysAndValues<T> as `${TRecord['key']}.` extends TRecord['key']
+    ? never
+    : TRecord['key']]: TRecord['value']
 }
 
 /**
@@ -161,15 +171,6 @@ export type DeepKeys<T> = unknown extends T
   ? string
   : DeepKeysAndValues<T>['key']
 
-/**
- * Infer the type of a deeply nested property within an object or an array.
- */
-export type DeepValue<TValue, TAccessor> = unknown extends TValue
-  ? TValue
-  : TAccessor extends DeepKeys<TValue>
-    ? DeepRecord<TValue>[TAccessor]
-    : never
-
 /**
  * The keys of an object or array, deeply nested and only with a value of TValue
  */
@@ -177,3 +178,15 @@ export type DeepKeysOfType<TData, TValue> = Extract<
   DeepKeysAndValues<TData>,
   AnyDeepKeyAndValue<string, TValue>
 >['key']
+
+type PickValue<T, K extends keyof T> = T[K]
+/**
+ * Infer the type of a deeply nested property within an object or an array.
+ */
+export type DeepValue<TValue, TAccessor> = unknown extends TValue
+  ? TValue
+  : TAccessor extends keyof DeepRecordWithStaticSuffix<TValue>
+    ? PickValue<DeepRecordWithStaticSuffix<TValue>, TAccessor>
+    : TAccessor extends keyof DeepRecordWithDynamicSuffix<TValue>
+      ? PickValue<DeepRecordWithDynamicSuffix<TValue>, TAccessor>
+      : never
diff --git a/packages/form-core/tests/util-types.test-d.ts b/packages/form-core/tests/util-types.test-d.ts
index 67086c745..813f6b50e 100644
--- a/packages/form-core/tests/util-types.test-d.ts
+++ b/packages/form-core/tests/util-types.test-d.ts
@@ -446,3 +446,39 @@ type AnyObjectExample4 = DeepValue<ObjectWithAny, 'obj.c'>
 expectTypeOf(0 as never as AnyObjectExample4).toEqualTypeOf<any>()
 type AnyObjectExample5 = DeepValue<ObjectWithAny, 'obj.d'>
 expectTypeOf(0 as never as AnyObjectExample5).toEqualTypeOf<number>()
+
+type RecordExample = {
+  records: Record<string, { a: string; b: number; c: { d: string } }>
+}
+
+expectTypeOf<DeepKeys<RecordExample>>().toEqualTypeOf<
+  | 'records'
+  | `records.${string}`
+  | `records.${string}.a`
+  | `records.${string}.b`
+  | `records.${string}.c`
+  | `records.${string}.c.d`
+>()
+expectTypeOf<DeepKeysOfType<RecordExample, string>>().toEqualTypeOf<
+  `records.${string}.a` | `records.${string}.c.d`
+>()
+expectTypeOf<DeepValue<RecordExample, 'records'>>().toEqualTypeOf<
+  Record<string, { a: string; b: number; c: { d: string } }>
+>()
+expectTypeOf<DeepValue<RecordExample, 'records.something'>>().toEqualTypeOf<{
+  a: string
+  b: number
+  c: { d: string }
+}>()
+expectTypeOf<
+  DeepValue<RecordExample, 'records.something.a'>
+>().toEqualTypeOf<string>()
+expectTypeOf<
+  DeepValue<RecordExample, 'records.something.b'>
+>().toEqualTypeOf<number>()
+expectTypeOf<DeepValue<RecordExample, 'records.something.c'>>().toEqualTypeOf<{
+  d: string
+}>()
+expectTypeOf<
+  DeepValue<RecordExample, 'records.something.c.d'>
+>().toEqualTypeOf<string>()