Fixed recursive type checking crash.

Author: ciscoheat

src/lib/stringPath.ts

@@ -23,7 +23,8 @@ export function mergePath(path: (string | number | symbol)[]) {
  */
 export type FormPath<T extends object> =
   | (string & StringPath<T>)
-  | FormPathLeaves<T>;
+  | FormPathLeaves<T>
+  | FormPathArrays<T>;
 
 /**
  * List paths in an object as string accessors, but only with non-objects as accessible properties.
@@ -34,8 +35,29 @@ export type FormPathLeaves<T extends object> = string & StringPathLeaves<T>;
 /**
  * List all arrays in an object as string accessors.
  */
-export type FormPathArrays<T extends object> = string &
-  Exclude<StringPath<T, true>, FormPathLeaves<T>>;
+export type FormPathArrays<T extends object> = string & StringPathArrays<T>;
+
+export type StringPathArrays<T extends object, Path extends string = ''> = {
+  [K in Extract<keyof T, string>]: NonNullable<T[K]> extends
+    | Date
+    | Set<unknown>
+    ? never
+    : NonNullable<T[K]> extends (infer U)[]
+    ?
+        | `${Path}${Path extends '' ? '' : '.'}${K}`
+        | StringPathArrays<
+            NonNullable<U>,
+            `${Path}${Path extends '' ? '' : '.'}${K}[${number}]`
+          >
+    : NonNullable<T[K]> extends object
+    ? StringPathArrays<
+        NonNullable<T[K]>,
+        `${Path}${Path extends '' ? '' : '.'}${K}`
+      >
+    : NonNullable<T> extends unknown[]
+    ? Path
+    : never;
+}[Extract<keyof T, string>];
 
 export type StringPath<
   T extends object,

src/paths.test-d.ts

@@ -6,7 +6,6 @@ import type {
   StringPathLeaves
 } from '$lib/stringPath';
 import { test } from 'vitest';
-import type { z } from 'zod';
 
 type Obj = {
   name: string;
@@ -21,6 +20,22 @@ type Obj = {
   names: string[];
 };
 
+type FormData = {
+  field1: string[] | null;
+  field2: {
+    subField1: number[] | null;
+    subField2: {
+      nestedField: boolean[] | null;
+    } | null;
+  } | null;
+  field3: {
+    nestedArray: {
+      innerArray: string[] | null;
+    }[];
+  };
+};
+type FormDataArrays = FormPathArrays<FormData>;
+
 const i = 7 + 3;
 
 type Test = StringPath<Obj>;

src/routes/tests/array-component/AutoComplete.svelte

@@ -5,7 +5,7 @@
 
 <script lang="ts" generics="T extends AnyZodObject">
   import type { z } from 'zod';
-  import type { ZodValidation, FormPath, FormPathArrays } from '$lib';
+  import type { ZodValidation, FormPathArrays } from '$lib';
   import type { Writable } from 'svelte/store';
   import { fieldProxy, type SuperForm } from '$lib/client';
 
@@ -15,10 +15,7 @@
   export let label = '';
 
   const value = fieldProxy(form.form, field) as Writable<unknown[]>;
-  const errors = fieldProxy(
-    form.errors,
-    `${field}._errors` as FormPath<z.infer<T>>
-  );
+  const errors = fieldProxy(form.errors, `${field}._errors` as any);
 </script>
 
 {#if label}<label for={field}>{label}</label>{/if}