epic-forms

Epic Stack: Forms

When to use this skill

Use this skill when you need to:

• Create forms in an Epic Stack application
• Implement form validation with Zod
• Work with Conform for progressively enhanced forms
• Handle file uploads
• Implement honeypot fields for spam protection
• Handle form errors
• Work with complex forms (fieldsets, arrays)

Patterns and conventions

Validation Philosophy

Following Epic Web principles:

Explicit is better than implicit - Make validation rules clear and explicit using Zod schemas. Every validation rule should be visible in the schema, not hidden in business logic. Error messages should be specific and helpful, telling users exactly what went wrong and how to fix it.

Design to fail fast and early - Validate input as early as possible, ideally on the client side before submission, and always on the server side. Return clear, specific error messages immediately so users can fix issues without frustration.

Example - Explicit validation:

// ✅ Good - Explicit validation with clear error messages
const SignupSchema = z.object({
	email: z
		.string({ required_error: 'Email is required' })
		.email({ message: 'Please enter a valid email address' })
		.min(3, { message: 'Email must be at least 3 characters' })
		.max(100, { message: 'Email must be less than 100 characters' })
		.transform((val) => val.toLowerCase().trim()),
	password: z
		.string({ required_error: 'Password is required' })
		.min(6, { message: 'Password must be at least 6 characters' })
		.max(72, { message: 'Password must be less than 72 characters' }),
})

// ❌ Avoid - Implicit validation
const SignupSchema = z.object({
	email: z.string().email(), // No clear error messages
	password: z.string().min(6), // Generic error
})

Example - Fail fast validation:

// ✅ Good - Validate early and return specific errors immediately
export async function action({ request }: Route.ActionArgs) {
	const formData = await request.formData()

	// Validate immediately - fail fast
	const submission = await parseWithZod(formData, {
		schema: SignupSchema,
	})

	// Return errors immediately if validation fails
	if (submission.status !== 'success') {
		return data(
			{ result: submission.reply() },
			{ status: 400 }, // Clear error status
		)
	}

	// Only proceed if validation passed
	const { email, password } = submission.value
	// ... continue with signup
}

// ❌ Avoid - Delayed or unclear validation
export async function action({ request }: Route.ActionArgs) {
	const formData = await request.formData()
	const email = formData.get('email')
	const password = formData.get('password')

	// Validation scattered throughout the function
	if (!email) {
		// Generic error, not specific
		return json({ error: 'Invalid' }, { status: 400 })
	}
	// ... more scattered validation
}

Basic setup with Conform

Epic Stack uses Conform to handle forms with progressive enhancement.

Basic setup:

import { getFormProps, useForm } from '@conform-to/react'
import { getZodConstraint, parseWithZod } from '@conform-to/zod'
import { z } from 'zod'
import { Form } from 'react-router'

const SignupSchema = z.object({
	email: z.string().email(),
	password: z.string().min(6),
})

export default function SignupRoute({ actionData }: Route.ComponentProps) {
	const [form, fields] = useForm({
		id: 'signup-form',
		constraint: getZodConstraint(SignupSchema),
		lastResult: actionData?.result,
		onValidate({ formData }) {
			return parseWithZod(formData, { schema: SignupSchema })
		},
		shouldRevalidate: 'onBlur',
	})

	return (
		<Form method="POST" {...getFormProps(form)}>
			{/* Form fields */}
		</Form>
	)
}

Integration with Zod

Conform integrates seamlessly with Zod for validation.

Define schema:

import { z } from 'zod'

const SignupSchema = z
	.object({
		email: z.string().email('Invalid email'),
		password: z.string().min(6, 'Password must be at least 6 characters'),
		confirmPassword: z.string(),
	})
	.superRefine(({ confirmPassword, password }, ctx) => {
		if (confirmPassword !== password) {
			ctx.addIssue({
				path: ['confirmPassword'],
				code: 'custom',
				message: 'Passwords must match',
			})
		}
	})

Validation in action (fail fast):

export async function action({ request }: Route.ActionArgs) {
	const formData = await request.formData()

	// Validate immediately - explicit and fail fast
	const submission = await parseWithZod(formData, {
		schema: SignupSchema,
	})

	// Return explicit errors immediately if validation fails
	if (submission.status !== 'success') {
		return data(
			{ result: submission.reply() },
			{ status: submission.status === 'error' ? 400 : 200 },
		)
	}

	// Only proceed if validation passed - submission.value is type-safe
	const { email, password } = submission.value
	// ... process with validated data
}

Async validation

For validations that require querying the database:

export async function action({ request }: Route.ActionArgs) {
	const formData = await request.formData()

	const submission = await parseWithZod(formData, {
		schema: SignupSchema.superRefine(async (data, ctx) => {
			const existingUser = await prisma.user.findUnique({
				where: { email: data.email },
				select: { id: true },
			})
			if (existingUser) {
				ctx.addIssue({
					path: ['email'],
					code: z.ZodIssueCode.custom,
					message: 'A user already exists with this email',
				})
			}
		}),
		async: true, // Important: enable async validation
	})

	if (submission.status !== 'success') {
		return data(
			{ result: submission.reply() },
			{ status: submission.status === 'error' ? 400 : 200 },
		)
	}

	// ...
}

Field Components

Epic Stack provides pre-built field components:

Basic Field:

import { Field, ErrorList } from '#app/components/forms.tsx'
import { getInputProps } from '@conform-to/react'

<Field
	labelProps={{
		htmlFor: fields.email.id,
		children: 'Email',
	}}
	inputProps={{
		...getInputProps(fields.email, { type: 'email' }),
		autoFocus: true,
		autoComplete: 'email',
	}}
	errors={fields.email.errors}
/>

TextareaField:

import { TextareaField } from '#app/components/forms.tsx'
import { getTextareaProps } from '@conform-to/react'

<TextareaField
	labelProps={{
		htmlFor: fields.content.id,
		children: 'Content',
	}}
	textareaProps={{
		...getTextareaProps(fields.content),
		rows: 10,
	}}
	errors={fields.content.errors}
/>

CheckboxField:

import { CheckboxField } from '#app/components/forms.tsx'
import { getInputProps } from '@conform-to/react'

<CheckboxField
	labelProps={{
		htmlFor: fields.remember.id,
		children: 'Remember me',
	}}
	buttonProps={getInputProps(fields.remember, { type: 'checkbox' })}
	errors={fields.remember.errors}
/>

OTPField:

import { OTPField } from '#app/components/forms.tsx'

<OTPField
	labelProps={{
		htmlFor: fields.code.id,
		children: 'Verification Code',
	}}
	inputProps={{
		...getInputProps(fields.code),
		maxLength: 6,
	}}
	errors={fields.code.errors}
/>

Error Handling

Display field errors:

<Field
	// ... props
	errors={fields.email.errors} // Errores específicos del campo
/>

Display form errors:

import { ErrorList } from '#app/components/forms.tsx'

<ErrorList errors={form.errors} id={form.errorId} />

Error structure:

• fields.fieldName.errors - Errors for a specific field
• form.errors - General form errors (like formErrors)

Honeypot Fields

Epic Stack includes spam protection with honeypot fields.

In the form:

import { HoneypotInputs } from 'remix-utils/honeypot/react'

<Form method="POST" {...getFormProps(form)}>
	<HoneypotInputs /> {/* Always include in public forms */}
	{/* Rest of fields */}
</Form>

In the action:

import { checkHoneypot } from '#app/utils/honeypot.server.ts'

export async function action({ request }: Route.ActionArgs) {
	const formData = await request.formData()

	await checkHoneypot(formData) // Throws error if spam

	// ... rest of code
}

File Uploads

For forms with file uploads, use encType="multipart/form-data".

Schema for files:

const MAX_UPLOAD_SIZE = 1024 * 1024 * 3 // 3MB

const ImageFieldsetSchema = z.object({
	id: z.string().optional(),
	file: z
		.instanceof(File)
		.optional()
		.refine((file) => {
			return !file || file.size <= MAX_UPLOAD_SIZE
		}, 'File must be less than 3MB'),
	altText: z.string().optional(),
})

const NoteEditorSchema = z.object({
	title: z.string().min(1).max(100),
	content: z.string().min(1).max(10000),
	images: z.array(ImageFieldsetSchema).max(5).optional(),
})

Form with file upload:

<Form
	method="POST"
	encType="multipart/form-data"
	{...getFormProps(form)}
>
	{/* Fields */}
</Form>

Process files in action:

export async function action({ request }: Route.ActionArgs) {
	const formData = await request.formData()

	const submission = await parseWithZod(formData, {
		schema: NoteEditorSchema,
	})

	if (submission.status !== 'success') {
		return data({ result: submission.reply() }, { status: 400 })
	}

	const { images } = submission.value

	// Process files
	for (const image of images ?? []) {
		if (image.file) {
			// Upload file, save to storage, etc.
		}
	}

	// ...
}

Fieldsets y Arrays

For forms with repetitive fields (like multiple images):

Schema:

const ImageFieldsetSchema = z.object({
	id: z.string().optional(),
	file: z.instanceof(File).optional(),
	altText: z.string().optional(),
})

const FormSchema = z.object({
	images: z.array(ImageFieldsetSchema).max(5).optional(),
})

In the component:

import { FormProvider, getFieldsetProps } from '@conform-to/react'

const [form, fields] = useForm({
	// ...
	default

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