From 37abcc6a5b0a678be626673af5067956657a50d6 Mon Sep 17 00:00:00 2001
From: Tankosin <tankosinn@gmail.com>
Date: Fri, 30 May 2025 16:29:01 +0300
Subject: [PATCH] fix(Form): conditionally type form data via `transform` prop
 (#4188)

Co-authored-by: Benjamin Canac <canacb1@gmail.com>
---
 src/runtime/components/Form.vue | 34 ++++++++++++++++-----------------
 src/runtime/types/form.ts       | 16 +++++++++-------
 2 files changed, 26 insertions(+), 24 deletions(-)

diff --git a/src/runtime/components/Form.vue b/src/runtime/components/Form.vue
index c5f4d5dc..a215c4a3 100644
--- a/src/runtime/components/Form.vue
+++ b/src/runtime/components/Form.vue
@@ -2,12 +2,12 @@
 import type { DeepReadonly } from 'vue'
 import type { AppConfig } from '@nuxt/schema'
 import theme from '#build/ui/form'
-import type { FormSchema, FormError, FormInputEvents, FormErrorEvent, FormSubmitEvent, FormEvent, Form, FormErrorWithId, InferInput, InferOutput } from '../types/form'
+import type { FormSchema, FormError, FormInputEvents, FormErrorEvent, FormSubmitEvent, FormEvent, Form, FormErrorWithId, InferInput, InferOutput, FormData } from '../types/form'
 import type { ComponentConfig } from '../types/utils'
 
 type FormConfig = ComponentConfig<typeof theme, AppConfig, 'form'>
 
-export interface FormProps<S extends FormSchema> {
+export interface FormProps<S extends FormSchema, T extends boolean = true> {
   id?: string | number
   /** Schema to validate the form state. Supports Standard Schema objects, Yup, Joi, and Superstructs. */
   schema?: S
@@ -35,7 +35,7 @@ export interface FormProps<S extends FormSchema> {
    * If true, schema transformations will be applied to the state on submit.
    * @defaultValue `true`
    */
-  transform?: boolean
+  transform?: T
 
   /**
    * If true, this form will attach to its parent Form (if any) and validate at the same time.
@@ -50,11 +50,11 @@ export interface FormProps<S extends FormSchema> {
    */
   loadingAuto?: boolean
   class?: any
-  onSubmit?: ((event: FormSubmitEvent<InferOutput<S>>) => void | Promise<void>) | (() => void | Promise<void>)
+  onSubmit?: ((event: FormSubmitEvent<FormData<S, T>>) => void | Promise<void>) | (() => void | Promise<void>)
 }
 
-export interface FormEmits<S extends FormSchema> {
-  (e: 'submit', payload: FormSubmitEvent<InferOutput<S>>): void
+export interface FormEmits<S extends FormSchema, T extends boolean = true> {
+  (e: 'submit', payload: FormSubmitEvent<FormData<S, T>>): void
   (e: 'error', payload: FormErrorEvent): void
 }
 
@@ -63,7 +63,7 @@ export interface FormSlots {
 }
 </script>
 
-<script lang="ts" setup generic="S extends FormSchema">
+<script lang="ts" setup generic="S extends FormSchema, T extends boolean = true">
 import { provide, inject, nextTick, ref, onUnmounted, onMounted, computed, useId, readonly } from 'vue'
 import { useEventBus } from '@vueuse/core'
 import { useAppConfig } from '#imports'
@@ -75,17 +75,17 @@ import { FormValidationException } from '../types/form'
 type I = InferInput<S>
 type O = InferOutput<S>
 
-const props = withDefaults(defineProps<FormProps<S>>(), {
+const props = withDefaults(defineProps<FormProps<S, T>>(), {
   validateOn() {
     return ['input', 'blur', 'change'] as FormInputEvents[]
   },
   validateOnInputDelay: 300,
   attach: true,
-  transform: true,
+  transform: () => true as T,
   loadingAuto: true
 })
 
-const emits = defineEmits<FormEmits<S>>()
+const emits = defineEmits<FormEmits<S, T>>()
 defineSlots<FormSlots>()
 
 const appConfig = useAppConfig() as FormConfig['AppConfig']
@@ -183,10 +183,10 @@ async function getErrors(): Promise<FormErrorWithId[]> {
   return resolveErrorIds(errs)
 }
 
-type ValidateOpts<Silent extends boolean> = { name?: keyof I | (keyof I)[], silent?: Silent, nested?: boolean, transform?: boolean }
-async function _validate(opts: ValidateOpts<false>): Promise<O>
-async function _validate(opts: ValidateOpts<true>): Promise<O | false>
-async function _validate(opts: ValidateOpts<boolean> = { silent: false, nested: true, transform: false }): Promise<O | false> {
+type ValidateOpts<Silent extends boolean, Transform extends boolean> = { name?: keyof I | (keyof I)[], silent?: Silent, nested?: boolean, transform?: Transform }
+async function _validate<T extends boolean>(opts: ValidateOpts<false, T>): Promise<FormData<S, T>>
+async function _validate<T extends boolean>(opts: ValidateOpts<true, T>): Promise<FormData<S, T> | false>
+async function _validate<T extends boolean>(opts: ValidateOpts<boolean, boolean> = { silent: false, nested: true, transform: false }): Promise<FormData<S, T> | false> {
   const names = opts.name && !Array.isArray(opts.name) ? [opts.name] : opts.name as (keyof O)[]
 
   const nestedValidatePromises = !names && opts.nested
@@ -227,7 +227,7 @@ async function _validate(opts: ValidateOpts<boolean> = { silent: false, nested:
     Object.assign(props.state, transformedState.value)
   }
 
-  return props.state as O
+  return props.state as FormData<S, T>
 }
 
 const loading = ref(false)
@@ -236,7 +236,7 @@ provide(formLoadingInjectionKey, readonly(loading))
 async function onSubmitWrapper(payload: Event) {
   loading.value = props.loadingAuto && true
 
-  const event = payload as FormSubmitEvent<O>
+  const event = payload as FormSubmitEvent<FormData<S, T>>
 
   try {
     event.data = await _validate({ nested: true, transform: props.transform })
@@ -265,7 +265,7 @@ provide(formOptionsInjectionKey, computed(() => ({
   validateOnInputDelay: props.validateOnInputDelay
 })))
 
-defineExpose<Form<I>>({
+defineExpose<Form<S>>({
   validate: _validate,
   errors,
 
diff --git a/src/runtime/types/form.ts b/src/runtime/types/form.ts
index 4ca43173..3749c370 100644
--- a/src/runtime/types/form.ts
+++ b/src/runtime/types/form.ts
@@ -5,20 +5,20 @@ import type { ObjectSchema as YupObjectSchema } from 'yup'
 import type { GetObjectField } from './utils'
 import type { Struct as SuperstructSchema } from 'superstruct'
 
-export interface Form<T extends object> {
-  validate (opts?: { name?: keyof T | (keyof T)[], silent?: boolean, nested?: boolean, transform?: boolean }): Promise<T | false>
+export interface Form<S extends FormSchema> {
+  validate<T extends boolean>(opts?: { name?: keyof FormData<S, false> | (keyof FormData<S, false>)[], silent?: boolean, nested?: boolean, transform?: T }): Promise<FormData<S, T> | false>
   clear (path?: string): void
   errors: Ref<FormError[]>
-  setErrors (errs: FormError[], name?: keyof T): void
-  getErrors (name?: keyof T): FormError[]
+  setErrors (errs: FormError[], name?: keyof FormData<S, false>): void
+  getErrors (name?: keyof FormData<S, false>): FormError[]
   submit (): Promise<void>
   disabled: ComputedRef<boolean>
   dirty: ComputedRef<boolean>
   loading: Ref<boolean>
 
-  dirtyFields: DeepReadonly<Set<keyof T>>
-  touchedFields: DeepReadonly<Set<keyof T>>
-  blurredFields: DeepReadonly<Set<keyof T>>
+  dirtyFields: DeepReadonly<Set<keyof FormData<S, false>>>
+  touchedFields: DeepReadonly<Set<keyof FormData<S, false>>>
+  blurredFields: DeepReadonly<Set<keyof FormData<S, false>>>
 }
 
 export type FormSchema<I extends object = object, O extends object = I> =
@@ -42,6 +42,8 @@ export type InferOutput<Schema> = Schema extends StandardSchemaV1 ? StandardSche
       : Schema extends SuperstructSchema<infer O, any> ? O
         : never
 
+export type FormData<S extends FormSchema, T extends boolean = true> = T extends true ? InferOutput<S> : InferInput<S>
+
 export type FormInputEvents = 'input' | 'blur' | 'change' | 'focus'
 
 export interface FormError<P extends string = string> {