refactor(Form): remove state assignment and opt-in to nested forms

docs/app/components/content/examples/form/FormExampleNested.vue

@@ -39,7 +39,7 @@ async function onSubmit(event: FormSubmitEvent<Schema>) {
       <UCheckbox v-model="state.news" name="news" label="Register to our newsletter" @update:model-value="state.email = undefined" />
     </div>
 
-    <UForm v-if="state.news" :state="state" :schema="nestedSchema">
+    <UForm v-if="state.news" :state="state" :schema="nestedSchema" nested>
       <UFormField label="Email" name="email">
         <UInput v-model="state.email" placeholder="john@lennon.com" />
       </UFormField>

docs/app/components/content/examples/form/FormExampleNestedList.vue

@@ -51,7 +51,14 @@ async function onSubmit(event: FormSubmitEvent<Schema>) {
       <UInput v-model="state.customer" placeholder="Wonka Industries" />
     </UFormField>
 
-    <UForm v-for="item, count in state.items" :key="count" :state="item" :schema="itemSchema" class="flex gap-2">
+    <UForm
+      v-for="item, count in state.items"
+      :key="count"
+      :state="item"
+      :schema="itemSchema"
+      nested
+      class="flex gap-2"
+    >
       <UFormField :label="!count ? 'Description' : undefined" name="description">
         <UInput v-model="item.description" />
       </UFormField>

playground/app/pages/components/form-sandro.vue

@@ -0,0 +1,71 @@
+<template>
+  <UContainer>
+    <UForm :schema :state @submit="onSubmit">
+      <UFormField label="A" name="a">
+        <UInput v-model="state.a" />
+      </UFormField>
+      <UFormField label="B" name="b">
+        <UInput v-model="state.b" />
+      </UFormField>
+
+      <UButton type="submit">
+        Submit
+      </UButton>
+    </UForm>
+
+    {{ output }}
+  </UContainer>
+</template>
+
+<script lang="ts" setup>
+import type { FormSubmitEvent } from '@nuxt/ui'
+import * as v from 'valibot'
+
+const _schemaStringFiltered = v.pipe(v.string(), v.trim())
+const schema = v.object({
+  a: v.string(),
+  b: v.union([
+    v.pipe(
+      v.array(_schemaStringFiltered),
+      v.filterItems((item, index, array) => (array.indexOf(item) === index || item !== ''))
+    ),
+    v.pipe(
+      v.string(),
+      v.trim(),
+      v.transform(
+        (item) => {
+          if (item === '') return undefined
+
+          return item
+            .split(',')
+            .map(val => val.trim())
+            .filter(val => val !== '')
+        }
+      )
+    )
+  ])
+})
+
+const state = reactive<{
+  a: string
+  b: string
+}>({
+  a: 'hello, world',
+  b: 'hello, world'
+})
+const output = reactive<{
+  a: string
+  b?: string[]
+}>({
+  a: '',
+  b: []
+})
+
+function onSubmit(event: FormSubmitEvent<v.InferOutput<typeof schema>>) {
+  console.log('typeof `a`:', typeof event.data.a) // should be string
+  console.log('typeof `b`:', typeof event.data.b) // should be object (array of strings)
+
+  output.a = event.data.a
+  output.b = event.data.b
+}
+</script>

src/runtime/components/Form.vue

@@ -19,7 +19,7 @@ export interface FormProps<I extends object, O extends object = I> {
    * @param state - The current state of the form.
    * @returns A promise that resolves to an array of FormError objects, or an array of FormError objects directly.
    */
-  validate?: (state: Partial<I> | O) => Promise<FormError[]> | FormError[]
+  validate?: (state: Partial<I>) => Promise<FormError[]> | FormError[]
   /**
    * The list of input events that trigger the form validation.
    * @defaultValue `['blur', 'change', 'input']`
@@ -32,11 +32,11 @@ export interface FormProps<I extends object, O extends object = I> {
    * @defaultValue `300`
    */
   validateOnInputDelay?: number
+
   /**
-   * If true, schema transformations will be applied to the state on submit.
+   * If true and nested in another form, this form will attach to its parent and validate at the same time.
-   * @defaultValue `true`
    */
-  transform?: boolean
+  nested?: boolean
   /**
    * When `true`, all form elements will be disabled on `@submit` event.
    * This will cause any focused input elements to lose their focus state.
@@ -71,7 +71,6 @@ const props = withDefaults(defineProps<FormProps<I, O>>(), {
     return ['input', 'blur', 'change'] as FormInputEvents[]
   },
   validateOnInputDelay: 300,
-  transform: true,
   loadingAuto: true
 })
 
@@ -127,14 +126,14 @@ onUnmounted(() => {
 })
 
 onMounted(async () => {
-  if (parentBus) {
+  if (props.nested && parentBus) {
     await nextTick()
     parentBus.emit({ type: 'attach', validate: _validate, formId })
   }
 })
 
 onUnmounted(() => {
-  if (parentBus) {
+  if (props.nested && parentBus) {
     parentBus.emit({ type: 'detach', formId })
   }
 })
@@ -173,7 +172,7 @@ async function getErrors(): Promise<FormErrorWithId[]> {
   return resolveErrorIds(errs)
 }
 
-async function _validate(opts: { name?: keyof I | (keyof I)[], silent?: boolean, nested?: boolean, transform?: boolean } = { silent: false, nested: true, transform: false }): Promise<O | false> {
+async function _validate(opts: { name?: keyof I | (keyof I)[], silent?: boolean, nested?: boolean } = { silent: false, nested: true }): Promise<O | false> {
   const names = opts.name && !Array.isArray(opts.name) ? [opts.name] : opts.name as (keyof I)[]
 
   const nestedValidatePromises = !names && opts.nested
@@ -210,11 +209,7 @@ async function _validate(opts: { name?: keyof I | (keyof I)[], silent?: boolean,
     throw new FormValidationException(formId, errors.value, childErrors)
   }
 
-  if (opts.transform) {
+  return transformedState.value
-    Object.assign(props.state, transformedState.value)
-  }
-
-  return props.state as O
 }
 
 const loading = ref(false)
@@ -226,7 +221,7 @@ async function onSubmitWrapper(payload: Event) {
   const event = payload as FormSubmitEvent<any>
 
   try {
-    event.data = await _validate({ nested: true, transform: props.transform })
+    event.data = await _validate({ nested: true })
     await props.onSubmit?.(event)
     dirtyFields.clear()
   } catch (error) {