fix: improve fields type for generic components (#14974)

* fix: improves fields type for generic components

* changeset

* fix generated types

* cleaner type for intellisense

---------

Co-authored-by: Elliott Johnson <elliott.johnson@vercel.com>

Author: sillvva

.changeset/shaky-bobcats-dig.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: improves fields type for generic components

packages/kit/src/exports/public.d.ts

@@ -15,7 +15,8 @@ import {
 	PrerenderUnseenRoutesHandlerValue,
 	PrerenderOption,
 	RequestOptions,
-	RouteSegment
+	RouteSegment,
+	IsAny
 } from '../types/private.js';
 import { BuildData, SSRNodeLoader, SSRRoute, ValidatedConfig } from 'types';
 import { SvelteConfig } from '@sveltejs/vite-plugin-svelte';
@@ -1953,6 +1954,18 @@ type UnknownField<Value> = RemoteFormFieldMethods<Value> & {
 	[key: string | number]: UnknownField<any>;
 };
 
+type RemoteFormFieldsRoot<Input extends RemoteFormInput | void> =
+	IsAny<Input> extends true
+		? RecursiveFormFields
+		: Input extends void
+			? {
+					/** Validation issues, if any */
+					issues(): RemoteFormIssue[] | undefined;
+					/** Validation issues belonging to this or any of the fields that belong to it, if any */
+					allIssues(): RemoteFormIssue[] | undefined;
+				}
+			: RemoteFormFields<Input>;
+
 /**
  * Recursive type to build form fields structure with proxy access
  */
@@ -2077,7 +2090,7 @@ export type RemoteForm<Input extends RemoteFormInput | void, Output> = {
 	/** The number of pending submissions */
 	get pending(): number;
 	/** Access form fields using object notation */
-	fields: RemoteFormFields<Input>;
+	fields: RemoteFormFieldsRoot<Input>;
 };
 
 /**

packages/kit/src/types/private.d.ts

@@ -241,3 +241,5 @@ export interface RouteSegment {
 }
 
 export type TrailingSlash = 'never' | 'always' | 'ignore';
+
+export type IsAny<T> = 0 extends 1 & T ? true : false;

packages/kit/test/types/remote.test.ts

@@ -1,6 +1,12 @@
 import { query, prerender, command, form } from '$app/server';
 import { StandardSchemaV1 } from '@standard-schema/spec';
-import { RemotePrerenderFunction, RemoteQueryFunction, invalid } from '@sveltejs/kit';
+import {
+	RemoteForm,
+	RemoteFormInput,
+	RemotePrerenderFunction,
+	RemoteQueryFunction,
+	invalid
+} from '@sveltejs/kit';
 
 const schema: StandardSchemaV1<string> = null as any;
 const schema2: StandardSchemaV1<string, number> = null as any;
@@ -359,6 +365,16 @@ function form_tests() {
 	// doesn't use data
 	const f9 = form(() => Promise.resolve({ success: true }));
 	f9.result?.success === true;
+
+	// generic form
+	function f10<
+		Schema extends StandardSchemaV1<RemoteFormInput, unknown>,
+		Form extends RemoteForm<StandardSchemaV1.InferInput<Schema>, unknown>
+	>(data: StandardSchemaV1.InferInput<Schema>, form: Form) {
+		form.fields.set(data);
+		form.fields.allIssues();
+	}
+	void f10;
 }
 form_tests();
 

packages/kit/types/index.d.ts

@@ -1929,6 +1929,18 @@ declare module '@sveltejs/kit' {
 		[key: string | number]: UnknownField<any>;
 	};
 
+	type RemoteFormFieldsRoot<Input extends RemoteFormInput | void> =
+		IsAny<Input> extends true
+			? RecursiveFormFields
+			: Input extends void
+				? {
+						/** Validation issues, if any */
+						issues(): RemoteFormIssue[] | undefined;
+						/** Validation issues belonging to this or any of the fields that belong to it, if any */
+						allIssues(): RemoteFormIssue[] | undefined;
+					}
+				: RemoteFormFields<Input>;
+
 	/**
 	 * Recursive type to build form fields structure with proxy access
 	 */
@@ -2053,7 +2065,7 @@ declare module '@sveltejs/kit' {
 		/** The number of pending submissions */
 		get pending(): number;
 		/** Access form fields using object notation */
-		fields: RemoteFormFields<Input>;
+		fields: RemoteFormFieldsRoot<Input>;
 	};
 
 	/**
@@ -2371,6 +2383,8 @@ declare module '@sveltejs/kit' {
 	}
 
 	type TrailingSlash = 'never' | 'always' | 'ignore';
+
+	type IsAny<T> = 0 extends 1 & T ? true : false;
 	interface Asset {
 		file: string;
 		size: number;