# TanStack Form

Build forms in React using TanStack Form and Zod.

## When to use

* Build a form with validation and error messages, using TanStack Form.
* Give the user feedback while they type.

## How it works

TanStack Form's `useForm` hook holds the form state, and `form.Field` with a render prop wraps each controlled input. The markup is built with the `Field` components, and validation runs on the client with Zod, with real-time feedback. The demo shows a `toast` from Sonner on submit.

## Example

```tsx
'use client'

/* eslint-disable react/no-children-prop */
"use client"

import * as React from "react"
import { useForm } from "@tanstack/react-form"
import { toast } from "sonner"

import { Toaster } from "@/shadcn/base/ui/sonner"
import * as z from "zod"

import { Button } from "@/shadcn/base/ui/button"
import {
  Card,
  CardContent,
  CardDescription,
  CardFooter,
  CardHeader,
  CardTitle,
} from "@/shadcn/base/ui/card"
import {
  Field,
  FieldDescription,
  FieldError,
  FieldGroup,
  FieldLabel,
} from "@/shadcn/base/ui/field"
import { Input } from "@/shadcn/base/ui/input"
import {
  InputGroup,
  InputGroupAddon,
  InputGroupText,
  InputGroupTextarea,
} from "@/shadcn/base/ui/input-group"

const formSchema = z.object({
  title: z
    .string()
    .min(5, "Bug title must be at least 5 characters.")
    .max(32, "Bug title must be at most 32 characters."),
  description: z
    .string()
    .min(20, "Description must be at least 20 characters.")
    .max(100, "Description must be at most 100 characters."),
})

export default function BugReportForm() {
  const form = useForm({
    defaultValues: {
      title: "",
      description: "",
    },
    validators: {
      onSubmit: formSchema,
    },
    onSubmit: async ({ value }) => {
      toast("You submitted the following values:", {
        description: (
          <pre className="mt-2 w-[320px] overflow-x-auto rounded-md bg-code p-4 text-code-foreground">
            <code>{JSON.stringify(value, null, 2)}</code>
          </pre>
        ),
        position: "bottom-right",
        classNames: {
          content: "flex flex-col gap-2",
        },
        style: {
          "--border-radius": "calc(var(--radius)  + 4px)",
        } as React.CSSProperties,
      })
    },
  })

  return (
    <>
    <Card className="w-full sm:max-w-md">
      <CardHeader>
        <CardTitle>Bug Report</CardTitle>
        <CardDescription>
          Help us improve by reporting bugs you encounter.
        </CardDescription>
      </CardHeader>
      <CardContent>
        <form
          id="bug-report-form"
          onSubmit={(e) => {
            e.preventDefault()
            form.handleSubmit()
          }}
        >
          <FieldGroup>
            <form.Field
              name="title"
              children={(field) => {
                const isInvalid =
                  field.state.meta.isTouched && !field.state.meta.isValid
                return (
                  <Field data-invalid={isInvalid}>
                    <FieldLabel htmlFor={field.name}>Bug Title</FieldLabel>
                    <Input
                      id={field.name}
                      name={field.name}
                      value={field.state.value}
                      onBlur={field.handleBlur}
                      onChange={(e) => field.handleChange(e.target.value)}
                      aria-invalid={isInvalid}
                      placeholder="Login button not working on mobile"
                      autoComplete="off"
                    />
                    {isInvalid && (
                      <FieldError errors={field.state.meta.errors} />
                    )}
                  </Field>
                )
              }}
            />
            <form.Field
              name="description"
              children={(field) => {
                const isInvalid =
                  field.state.meta.isTouched && !field.state.meta.isValid
                return (
                  <Field data-invalid={isInvalid}>
                    <FieldLabel htmlFor={field.name}>Description</FieldLabel>
                    <InputGroup>
                      <InputGroupTextarea
                        id={field.name}
                        name={field.name}
                        value={field.state.value}
                        onBlur={field.handleBlur}
                        onChange={(e) => field.handleChange(e.target.value)}
                        placeholder="I'm having an issue with the login button on mobile."
                        rows={6}
                        className="min-h-24 resize-none"
                        aria-invalid={isInvalid}
                      />
                      <InputGroupAddon align="block-end">
                        <InputGroupText className="tabular-nums">
                          {field.state.value.length}/100 characters
                        </InputGroupText>
                      </InputGroupAddon>
                    </InputGroup>
                    <FieldDescription>
                      Include steps to reproduce, expected behavior, and what
                      actually happened.
                    </FieldDescription>
                    {isInvalid && (
                      <FieldError errors={field.state.meta.errors} />
                    )}
                  </Field>
                )
              }}
            />
          </FieldGroup>
        </form>
      </CardContent>
      <CardFooter>
        <Field orientation="horizontal">
          <Button type="button" variant="outline" onClick={() => form.reset()}>
            Reset
          </Button>
          <Button type="submit" form="bug-report-form">
            Submit
          </Button>
        </Field>
      </CardFooter>
    </Card>
    {/* The official docs mount <Toaster /> once in the root layout; the demo mounts it here. */}
    <Toaster />
    </>
  )
}
```

## Reference

Official page: https://ui.shadcn.com/docs/forms/tanstack-form