From b28f6d872a4a6f578498175213ebeb18aaad4fcf Mon Sep 17 00:00:00 2001
From: Sagnik Pradhan <markten6321@gmail.com>
Date: Sat, 17 Feb 2024 18:23:01 +0530
Subject: [PATCH] fix: Partial form types (#599)

Co-authored-by: Aadit Olkar <63646058+aadito123@users.noreply.github.com>
---
 .../form-core/src/tests/FieldApi.test-d.ts    | 60 +++++++++++++++++++
 packages/form-core/src/utils.ts               | 20 +++----
 2 files changed, 69 insertions(+), 11 deletions(-)

diff --git a/packages/form-core/src/tests/FieldApi.test-d.ts b/packages/form-core/src/tests/FieldApi.test-d.ts
index bd4c55f78..2daee12d5 100644
--- a/packages/form-core/src/tests/FieldApi.test-d.ts
+++ b/packages/form-core/src/tests/FieldApi.test-d.ts
@@ -19,6 +19,66 @@ it('should type value properly', () => {
   assertType<'test'>(field.getValue())
 })
 
+it('should type value when nothing is passed into constructor', () => {
+  type FormValues = {
+    name?: string
+    age?: number
+  }
+
+  const form = new FormApi<FormValues>()
+
+  const field = new FieldApi({
+    form,
+    name: 'name' as const,
+  })
+
+  assertType<string | undefined>(field.state.value)
+  assertType<'name'>(field.options.name)
+  assertType<string | undefined>(field.getValue())
+})
+
+it('should type required fields in constructor', () => {
+  type FormValues = {
+    name: string
+    age?: number
+  }
+
+  const form = new FormApi<FormValues>({
+    defaultValues: {
+      name: 'test',
+    },
+  })
+
+  const field = new FieldApi({
+    form,
+    name: 'name' as const,
+  })
+
+  assertType<string>(field.state.value)
+  assertType<'name'>(field.options.name)
+  assertType<string>(field.getValue())
+})
+
+it('should type value properly for completely partial forms', () => {
+  type CompletelyPartialFormValues = {
+    name?: 'test'
+    age?: number
+  }
+
+  const form = new FormApi<CompletelyPartialFormValues>({
+    defaultValues: {},
+  })
+
+  const field = new FieldApi({
+    form,
+    name: 'name' as const,
+  })
+
+  assertType<'test' | undefined>(field.state.value)
+  assertType<'name'>(field.options.name)
+  assertType<'test' | undefined>(field.getValue())
+})
+
 it('should type onChange properly', () => {
   const form = new FormApi({
     defaultValues: {
diff --git a/packages/form-core/src/utils.ts b/packages/form-core/src/utils.ts
index db2909687..fb7cf3196 100644
--- a/packages/form-core/src/utils.ts
+++ b/packages/form-core/src/utils.ts
@@ -300,17 +300,15 @@ export type DeepKeys<T, TDepth extends any[] = []> = TDepth['length'] extends 5
   ? never
   : unknown extends T
     ? string
-    : object extends T
-      ? string
-      : T extends readonly any[] & IsTuple<T>
-        ? AllowedIndexes<T> | DeepKeysPrefix<T, AllowedIndexes<T>, TDepth>
-        : T extends any[]
-          ? DeepKeys<T[number], [...TDepth, any]>
-          : T extends Date
-            ? never
-            : T extends object
-              ? (keyof T & string) | DeepKeysPrefix<T, keyof T, TDepth>
-              : never
+    : T extends readonly any[] & IsTuple<T>
+      ? AllowedIndexes<T> | DeepKeysPrefix<T, AllowedIndexes<T>, TDepth>
+      : T extends any[]
+        ? DeepKeysPrefix<T, number, TDepth>
+        : T extends Date
+          ? never
+          : T extends object
+            ? (keyof T & string) | DeepKeysPrefix<T, keyof T, TDepth>
+            : never
 
 type DeepKeysPrefix<
   T,