Formulario — logic2b/ui

import { zodResolver } from "@hookform/resolvers/zod"
import { useForm } from "react-hook-form"
import { z } from "zod"

import { Button } from "@/components/ui/button"
import {
  Form,
  FormControl,
  FormDescription,
  FormField,
  FormItem,
  FormLabel,
  FormMessage,
} from "@/components/ui/form"
import { Input } from "@/components/ui/input"

const formSchema = z.object({
  username: z.string().min(2, {
    message: "Username must be at least 2 characters.",
  }),
})

export default function FormDemo() {
  const form = useForm<z.infer<typeof formSchema>>({
    resolver: zodResolver(formSchema),
    defaultValues: {
      username: "",
    },
  })

  function onSubmit(values: z.infer<typeof formSchema>) {
    console.log(values)
  }

  return (
    <Form {...form}>
      <form
        onSubmit={form.handleSubmit(onSubmit)}
        className="w-full max-w-sm space-y-6"
      >
        <FormField
          control={form.control}
          name="username"
          render={({ field }) => (
            <FormItem>
              <FormLabel>Username</FormLabel>
              <FormControl>
                <Input placeholder="logic2b" {...field} />
              </FormControl>
              <FormDescription>
                This is your public display name.
              </FormDescription>
              <FormMessage />
            </FormItem>
          )}
        />
        <Button type="submit">Submit</Button>
      </form>
    </Form>
  )
}

Instalación

npx logic2b@next add form

¿Trabajas con un asistente de IA? Copia este prompt en Claude Code, Cursor o Copilot: incluye los pasos de instalación, una alternativa sin CLI y una lista de verificación.

Add the "form" item from the logic2b ui registry (https://ui.logic2b.com) to this project. Follow every step and verify at the end.

## Steps

1. If the project has no `components.json` yet, set up logic2b ui first:

   ```bash
   npx logic2b@next init
   ```

2. Install the item (the CLI resolves registry dependencies automatically):

   ```bash
   npx logic2b@next add form
   ```

3. Install any npm dependencies the command prints.

## If the CLI is not available

Do it manually from the registry payload:

1. Fetch https://ui.logic2b.com/r/form.json.
2. Write every entry in `files[]` to its mapped project path (see below).
3. Repeat (recursively) for each name in `registryDependencies`.
4. Install every package listed in `dependencies` across those payloads.

## Registry reference

- Index of every item: https://ui.logic2b.com/r/index.json
- Item payload (full source): https://ui.logic2b.com/r/<name>.json
- Usage examples per item: https://ui.logic2b.com/r/demos/index.json → https://ui.logic2b.com/r/demos/<demo>.json
- Docs index for agents: https://ui.logic2b.com/llms.txt (full docs: https://ui.logic2b.com/llms-full.txt)
- Every docs page is Markdown when you append `.md` to its URL.

Registry file paths map to project paths like this:
- `ui/*` → `@/components/ui/*`
- `blocks/<name>/*` → `@/components/*`
- `charts/*` → `@/components/charts/*`
- `hooks/*` → `@/hooks/*`
- `lib/utils.ts` → `@/lib/utils.ts`
- `theme.css` → next to the project's Tailwind entry stylesheet

## Conventions (do not break these)

- Tailwind CSS v4 (CSS-first config; no tailwind.config.js needed) and React 19.
- All colors go through semantic tokens (`bg-primary`, `text-muted-foreground`,
  `border-border`, …). Never hardcode hex/oklch values in components.
- Dark mode is class-based: toggle `.dark` on `<html>`.
- Icons come from lucide-react.

## Verify before finishing

1. The dev server starts and the app renders without console errors.
2. TypeScript compiles (`tsc --noEmit` or the framework's check).
3. Components use the theme: a `<Button>` shows the primary token color,
   and toggling `.dark` on `<html>` switches the palette.

Instala las dependencias:

npm install radix-ui react-hook-form @hookform/resolvers zod

Copia el contenido en ui/form.tsx:

"use client"

import * as React from "react"
import { Slot } from "radix-ui"
import {
  Controller,
  FormProvider,
  useFormContext,
  useFormState,
  type ControllerProps,
  type FieldPath,
  type FieldValues,
} from "react-hook-form"

import { cn } from "@/lib/utils"
import { Label } from "@/components/ui/label"

const Form = FormProvider

type FormFieldContextValue<
  TFieldValues extends FieldValues = FieldValues,
  TName extends FieldPath<TFieldValues> = FieldPath<TFieldValues>,
> = {
  name: TName
}

const FormFieldContext = React.createContext<FormFieldContextValue>(
  {} as FormFieldContextValue
)

function FormField<
  TFieldValues extends FieldValues = FieldValues,
  TName extends FieldPath<TFieldValues> = FieldPath<TFieldValues>,
>({ ...props }: ControllerProps<TFieldValues, TName>) {
  return (
    <FormFieldContext.Provider value={{ name: props.name }}>
      <Controller {...props} />
    </FormFieldContext.Provider>
  )
}

function useFormField() {
  const fieldContext = React.useContext(FormFieldContext)
  const itemContext = React.useContext(FormItemContext)
  const { getFieldState } = useFormContext()
  const formState = useFormState({ name: fieldContext.name })
  const fieldState = getFieldState(fieldContext.name, formState)

  if (!fieldContext) {
    throw new Error("useFormField should be used within <FormField>")
  }

  const { id } = itemContext

  return {
    id,
    name: fieldContext.name,
    formItemId: `${id}-form-item`,
    formDescriptionId: `${id}-form-item-description`,
    formMessageId: `${id}-form-item-message`,
    ...fieldState,
  }
}

type FormItemContextValue = {
  id: string
}

const FormItemContext = React.createContext<FormItemContextValue>(
  {} as FormItemContextValue
)

function FormItem({ className, ...props }: React.ComponentProps<"div">) {
  const id = React.useId()

  return (
    <FormItemContext.Provider value={{ id }}>
      <div
        data-slot="form-item"
        className={cn("grid gap-2", className)}
        {...props}
      />
    </FormItemContext.Provider>
  )
}

function FormLabel({
  className,
  ...props
}: React.ComponentProps<typeof Label>) {
  const { error, formItemId } = useFormField()

  return (
    <Label
      data-slot="form-label"
      data-error={!!error}
      className={cn("data-[error=true]:text-destructive", className)}
      htmlFor={formItemId}
      {...props}
    />
  )
}

function FormControl({ ...props }: React.ComponentProps<typeof Slot.Root>) {
  const { error, formItemId, formDescriptionId, formMessageId } =
    useFormField()

  return (
    <Slot.Root
      data-slot="form-control"
      id={formItemId}
      aria-describedby={
        !error
          ? `${formDescriptionId}`
          : `${formDescriptionId} ${formMessageId}`
      }
      aria-invalid={!!error}
      {...props}
    />
  )
}

function FormDescription({ className, ...props }: React.ComponentProps<"p">) {
  const { formDescriptionId } = useFormField()

  return (
    <p
      data-slot="form-description"
      id={formDescriptionId}
      className={cn("text-muted-foreground text-sm", className)}
      {...props}
    />
  )
}

function FormMessage({ className, ...props }: React.ComponentProps<"p">) {
  const { error, formMessageId } = useFormField()
  const body = error ? String(error?.message ?? "") : props.children

  if (!body) {
    return null
  }

  return (
    <p
      data-slot="form-message"
      id={formMessageId}
      className={cn("text-destructive text-sm", className)}
      {...props}
    >
      {body}
    </p>
  )
}

export {
  useFormField,
  Form,
  FormItem,
  FormLabel,
  FormControl,
  FormDescription,
  FormMessage,
  FormField,
}

Anatomía

import { useForm } from "react-hook-form"
import { zodResolver } from "@hookform/resolvers/zod"
import { z } from "zod"

import {
  Form,
  FormControl,
  FormDescription,
  FormField,
  FormItem,
  FormLabel,
  FormMessage,
} from "@/components/ui/form"

const formSchema = z.object({
  username: z.string().min(2),
})

function ProfileForm() {
  const form = useForm<z.infer<typeof formSchema>>({
    resolver: zodResolver(formSchema),
    defaultValues: { username: "" },
  })

  return (
    <Form {...form}>
      <form onSubmit={form.handleSubmit(console.log)}>
        <FormField
          control={form.control}
          name="username"
          render={({ field }) => (
            <FormItem>
              <FormLabel>Nombre de usuario</FormLabel>
              <FormControl>
                <input {...field} />
              </FormControl>
              <FormDescription>Tu nombre público.</FormDescription>
              <FormMessage />
            </FormItem>
          )}
        />
      </form>
    </Form>
  )
}

FormField envuelve el Controller de react-hook-form y proporciona el contexto del campo a FormLabel, FormControl, FormDescription y FormMessage. Estas piezas leen el error y el identificador desde ese contexto, por lo que etiquetas y mensajes permanecen conectados al control correcto.

Notas de uso

Form es un alias de FormProvider. Pásale el valor devuelto por useForm; el resto de piezas consumen su contexto.

Ejemplos

Inicio de sesión

Valida un correo electrónico y una contraseña con zod.

"use client"

import { zodResolver } from "@hookform/resolvers/zod"
import { useForm } from "react-hook-form"
import { z } from "zod"

import { Button } from "@/components/ui/button"
import {
  Form,
  FormControl,
  FormField,
  FormItem,
  FormLabel,
  FormMessage,
} from "@/components/ui/form"
import { Input } from "@/components/ui/input"

const formSchema = z.object({
  email: z.email({ message: "Enter a valid email address." }),
  password: z.string().min(8, {
    message: "Password must be at least 8 characters.",
  }),
})

export default function FormSigninDemo() {
  const form = useForm<z.infer<typeof formSchema>>({
    resolver: zodResolver(formSchema),
    defaultValues: {
      email: "",
      password: "",
    },
  })

  function onSubmit(values: z.infer<typeof formSchema>) {
    console.log(values)
  }

  return (
    <Form {...form}>
      <form
        onSubmit={form.handleSubmit(onSubmit)}
        className="w-full max-w-sm space-y-6"
      >
        <FormField
          control={form.control}
          name="email"
          render={({ field }) => (
            <FormItem>
              <FormLabel>Email</FormLabel>
              <FormControl>
                <Input placeholder="you@example.com" {...field} />
              </FormControl>
              <FormMessage />
            </FormItem>
          )}
        />
        <FormField
          control={form.control}
          name="password"
          render={({ field }) => (
            <FormItem>
              <FormLabel>Password</FormLabel>
              <FormControl>
                <Input type="password" {...field} />
              </FormControl>
              <FormMessage />
            </FormItem>
          )}
        />
        <Button type="submit">Sign in</Button>
      </form>
    </Form>
  )
}

Área de texto

"use client"

import { zodResolver } from "@hookform/resolvers/zod"
import { useForm } from "react-hook-form"
import { z } from "zod"

import { Button } from "@/components/ui/button"
import {
  Form,
  FormControl,
  FormDescription,
  FormField,
  FormItem,
  FormLabel,
  FormMessage,
} from "@/components/ui/form"
import { Textarea } from "@/components/ui/textarea"

const formSchema = z.object({
  bio: z
    .string()
    .min(10, { message: "Bio must be at least 10 characters." })
    .max(160, { message: "Bio must not exceed 160 characters." }),
})

export default function FormTextareaDemo() {
  const form = useForm<z.infer<typeof formSchema>>({
    resolver: zodResolver(formSchema),
    defaultValues: {
      bio: "",
    },
  })

  function onSubmit(values: z.infer<typeof formSchema>) {
    console.log(values)
  }

  return (
    <Form {...form}>
      <form
        onSubmit={form.handleSubmit(onSubmit)}
        className="w-full max-w-sm space-y-6"
      >
        <FormField
          control={form.control}
          name="bio"
          render={({ field }) => (
            <FormItem>
              <FormLabel>Bio</FormLabel>
              <FormControl>
                <Textarea
                  placeholder="Tell us a little bit about yourself"
                  className="resize-none"
                  {...field}
                />
              </FormControl>
              <FormDescription>
                This appears on your public profile.
              </FormDescription>
              <FormMessage />
            </FormItem>
          )}
        />
        <Button type="submit">Save</Button>
      </form>
    </Form>
  )
}

Accesibilidad

FormControl obtiene id, aria-describedby y aria-invalid del contexto del campo. La etiqueta, la descripción y el error quedan conectados sin coordinar htmlFor e id manualmente.
Cuando falla la validación, FormMessage muestra el error con el identificador referenciado por aria-describedby, mientras FormLabel adopta el estado destructivo. El error se comunica visualmente y a tecnologías de asistencia.
Cada control recibe un identificador generado único, incluso cuando un campo se reutiliza dentro de una lista.

Playground interactivo

Edita las propiedades del componente y revisa el JSX exacto antes de copiarlo. La vista previa se carga solo cuando esta sección entra en pantalla.

JSX generado

const form = useForm({
  defaultValues: { username: "" },
})

return (
  <Form {...form}>
    <form onSubmit={form.handleSubmit(console.log)}>
      <FormField
        control={form.control}
        name="username"
        rules={{ required: "Username is required." }}
        render={({ field }) => (
          <FormItem>
            <FormLabel>Username</FormLabel>
            <FormControl>
              <Input
                {...field}
                placeholder={"logic2b"}
              />
            </FormControl>
            <FormDescription>{"This is your public display name."}</FormDescription>
            <FormMessage />
          </FormItem>
        )}
      />
      <Button type="submit">Save profile</Button>
    </form>
  </Form>
)

Referencia de API

Generada a partir de las exportaciones públicas de TypeScript en src/ui/form.tsx. Las descripciones técnicas conservan el texto canónico del código fuente.

Ver JSON

useFormField

Hook

(): { invalid: boolean; isDirty: boolean; isTouched: boolean; isValidating: boolean; error?: FieldError; id: string; name: string; formItemId: string; formDescriptionId: string; formMessageId: string; }

Form

Componente

Alias directo de FormProvider.

FormItem

Componente

Props: React.ComponentProps<"div">

FormLabel

Componente

Props: React.ComponentProps<typeof Label>

FormControl

Componente

Props: React.ComponentProps<typeof Slot.Root>

FormDescription

Componente

Props: React.ComponentProps<"p">

FormMessage

Componente

Props: React.ComponentProps<"p">

FormField

Componente

Props: ControllerProps<TFieldValues, TName>

Contrato de accesibilidad

Comportamiento legible por máquinas y responsabilidades de quien integra form. Los detalles normativos conservan el texto canónico del registro.

Ver JSON

Soporte: Comportamiento implementado
Patrón: form validation; React Hook Form + Radix Label

Semántica incorporada

FormControl derives id, aria-invalid and aria-describedby from field state.
Descriptions and error messages receive stable ids.

Responsabilidades de integración

Render FormLabel and useful error text; move focus or provide a summary after failed submission.