fix(form-core): types to pass most tests

packages/form-core/src/util-types.ts

@@ -21,35 +21,58 @@ export type Narrow<A> = Try<A, [], NarrowRaw<A>>
 
 type IsAny<T> = 0 extends 1 & T ? true : false
 
-export type ArrayAccessor<TPrefix extends string> = `${TPrefix}[${number}]`
+export interface AnyDeepKeyAndValue {
+  key: string
+  value: any
+}
+
+export type ArrayAccessor<TParent extends AnyDeepKeyAndValue> =
+  `${TParent['key'] extends never ? '' : TParent['key']}[${number}]`
+
+export interface ArrayDeepKeyAndValue<
+  in out TParent extends AnyDeepKeyAndValue,
+  in out T extends ReadonlyArray<any>,
+> {
+  key: ArrayAccessor<TParent>
+  value: T[number] | Nullable<TParent['value']>
+}
 
-export type DeepRecordArrayUnion<
+export type DeepKeyAndValueArray<
+  TParent extends AnyDeepKeyAndValue,
   T extends ReadonlyArray<any>,
-  TPrefix extends string,
   TAcc,
-> = DeepRecordUnion<
-  T[number],
-  ArrayAccessor<TPrefix>,
-  TAcc | Record<ArrayAccessor<TPrefix>, T[number]>
+> = DeepKeysAndValues<
+  NonNullable<T[number]>,
+  ArrayDeepKeyAndValue<TParent, T>,
+  TAcc | ArrayDeepKeyAndValue<TParent, T>
 >
 
 export type TupleAccessor<
-  TPrefix extends string,
-  TKey,
-> = `${TPrefix}[${TKey & string}]`
+  TParent extends AnyDeepKeyAndValue,
+  TKey extends string,
+> = `${TParent['key'] extends never ? '' : TParent['key']}[${TKey}]`
+
+export interface TupleDeepKeyAndValue<
+  in out TParent extends AnyDeepKeyAndValue,
+  in out T,
+  in out TKey extends AllTupleKeys<T>,
+> {
+  key: TupleAccessor<TParent, TKey>
+  value: T[TKey] | Nullable<TParent['value']>
+}
 
 export type AllTupleKeys<T> = T extends any ? keyof T & `${number}` : never
 
-export type DeepRecordTupleUnion<
+export type DeepKeyAndValueTuple<
+  TParent extends AnyDeepKeyAndValue,
   T extends ReadonlyArray<any>,
-  TPrefix extends string,
   TAcc,
   TAllKeys extends AllTupleKeys<T> = AllTupleKeys<T>,
 > = TAllKeys extends any
-  ? DeepRecordUnion<
-      T[TAllKeys],
-      TupleAccessor<TPrefix, TAllKeys>,
-      TAcc | Record<TupleAccessor<TPrefix, TAllKeys>, T[TAllKeys]>
+  ? DeepKeysAndValues<
+      NonNullable<T[TAllKeys]>,
+      TupleDeepKeyAndValue<TParent, T, TAllKeys>,
+      TAcc | TupleDeepKeyAndValue<TParent, T, TAllKeys>
     >
   : never
 
@@ -58,53 +81,85 @@ export type AllObjectKeys<T> = T extends any
   : never
 
 export type ObjectAccessor<
-  TPrefix extends string,
+  TParent extends AnyDeepKeyAndValue,
   TKey extends string | number,
-> = TPrefix extends '' ? `${TKey}` : `${TPrefix}.${TKey}`
+> = TParent['key'] extends never ? `${TKey}` : `${TParent['key']}.${TKey}`
+
+export type Nullable<T> = T & (undefined | null)
+
+export interface ObjectDeepKeyAndValue<
+  in out TParent extends AnyDeepKeyAndValue,
+  in out T,
+  in out TKey extends AllObjectKeys<T>,
+> {
+  key: ObjectAccessor<TParent, TKey>
+  value: T[TKey] | Nullable<TParent['value']>
+}
 
-export type DeepRecordObjectUnion<
+export type DeepKeyAndValueObject<
+  TParent extends AnyDeepKeyAndValue,
   T,
-  TPrefix extends string,
   TAcc,
   TAllKeys extends AllObjectKeys<T> = AllObjectKeys<T>,
 > = TAllKeys extends any
-  ? DeepRecordUnion<
-      T[TAllKeys],
-      ObjectAccessor<TPrefix, TAllKeys>,
-      TAcc | Record<ObjectAccessor<TPrefix, TAllKeys>, T[TAllKeys]>
+  ? DeepKeysAndValues<
+      NonNullable<T[TAllKeys]>,
+      ObjectDeepKeyAndValue<TParent, T, TAllKeys>,
+      TAcc | ObjectDeepKeyAndValue<TParent, T, TAllKeys>
     >
   : never
 
-export type DeepRecordUnion<T, TPrefix extends string = '', TAcc = never> =
+export type UnknownAccessor<TParent extends AnyDeepKeyAndValue> =
+  TParent['key'] extends never ? string : `${TParent['key']}.${string}`
+
+export interface UnknownDeepKeyAndValue<TParent extends AnyDeepKeyAndValue> {
+  key: UnknownAccessor<TParent>
+  value: unknown
+}
+
+export type DeepKeyAndValueUnknown<TParent extends AnyDeepKeyAndValue> =
+  UnknownDeepKeyAndValue<TParent>
+
+export type DeepKeysAndValues<
+  T,
+  TParent extends AnyDeepKeyAndValue = never,
+  TAcc = never,
+> =
   IsAny<T> extends true
     ? T
     : T extends string | number | boolean | bigint | Date
       ? TAcc
       : T extends ReadonlyArray<any>
         ? number extends T['length']
-          ? DeepRecordArrayUnion<T, TPrefix, TAcc>
-          : DeepRecordTupleUnion<T, TPrefix, TAcc>
-        : T extends object
-          ? DeepRecordObjectUnion<T, TPrefix, TAcc>
-          : TAcc
+          ? DeepKeyAndValueArray<TParent, T, TAcc>
+          : DeepKeyAndValueTuple<TParent, T, TAcc>
+        : keyof T extends never
+          ? TAcc | DeepKeyAndValueUnknown<TParent>
+          : T extends object
+            ? DeepKeyAndValueObject<TParent, T, TAcc>
+            : TAcc
 
 export type DeepRecord<T> = {
-  [TRecord in DeepRecordUnion<T> as keyof TRecord]: TRecord[keyof TRecord]
+  [TRecord in DeepKeysAndValues<T> extends AnyDeepKeyAndValue
+    ? DeepKeysAndValues<T>
+    : never as TRecord['key']]: TRecord['value']
 }
 
-type UnionKeys<T> = T extends any ? keyof T : never
-
 /**
  * The keys of an object or array, deeply nested.
  */
 export type DeepKeys<T> = unknown extends T
   ? string
-  : UnionKeys<DeepRecordUnion<T>> & string
+  : DeepKeysAndValues<T> extends AnyDeepKeyAndValue
+    ? DeepKeysAndValues<T>['key']
+    : never
 
 /**
  * Infer the type of a deeply nested property within an object or an array.
  */
 export type DeepValue<TValue, TAccessor> =
   DeepRecord<TValue> extends infer TDeepRecord
-    ? TDeepRecord[TAccessor & keyof TDeepRecord]
+    ? TAccessor extends keyof TDeepRecord
+      ? TDeepRecord[TAccessor]
+      : never
     : never

packages/form-core/tests/FieldApi.test-d.ts

@@ -134,7 +134,7 @@ it('should type an array sub-field properly', () => {
 
   const field = new FieldApi({
     form,
-    name: `nested.people[${1}].name`,
+    name: `nested.people[1].name`,
     validators: {
       onChangeAsync: async ({ value }) => {
         assertType<string>(value)