SKILL.md
shadcn/ui for Inertia Rails
shadcn/ui patterns adapted for Inertia.js + Rails + React. NOT Next.js.
Before using a shadcn example, ask:
- Does it use
react-hook-form+zod? → Replace with Inertia<Form>+nameattributes. Inertia handles CSRF, errors, redirects, processing state — react-hook-form would fight all of this. - Does it use
'use client'? → Remove it. Inertia has no RSC — all components are client components. - Does it use
next/link,next/head,useRouter()? → Replace with Inertia<Link>,<Head>,router.
Key Differences from Next.js Defaults
| shadcn default (Next.js) | Inertia equivalent |
|---|---|
'use client' directive |
Remove — not needed (no RSC) |
react-hook-form + zod |
Inertia <Form> component |
FormField, FormItem, FormMessage |
Plain <Input name="..."> + errors.field |
next-themes |
CSS class strategy + @custom-variant |
useRouter() (Next) |
router from @inertiajs/react |
next/link |
<Link> from @inertiajs/react |
next/head |
<Head> from @inertiajs/react |
NEVER use shadcn's FormField, FormItem, FormLabel, FormMessage components — they depend on react-hook-form's useFormContext internally and will crash without it. Use plain shadcn Input/Label/Select with name attributes inside Inertia <Form>, and render errors from the render function's errors object (see examples below).
Setup
npx shadcn@latest init. add @/ resolve aliases to tsconfig.json if not present, Do NOT add @/ resolve aliases to vite.config.ts — vite-plugin-ruby already provides them.
shadcn Inputs in Inertia <Form>
Use plain shadcn Input/Label/Button with name attributes inside Inertia <Form>. See inertia-rails-forms skill for full <Form> API — this section covers shadcn-specific adaptation only.
The key pattern: Replace shadcn's FormField/FormItem/FormMessage with plain components + manual error display:
// shadcn error display pattern (replaces FormMessage):
<Label htmlFor="name">Name</Label>
<Input id="name" name="name" />
{errors.name && <p className="text-sm text-destructive">{errors.name}</p>}<Select> requires name prop for Inertia <Form> integration — shadcn examples omit it because react-hook-form manages values differently:
<Select name="role" defaultValue="member">
<SelectTrigger><SelectValue placeholder="Select role" /></SelectTrigger>
<SelectContent>
<SelectItem value="admin">Admin</SelectItem>
<SelectItem value="member">Member</SelectItem>
</SelectContent>
</Select>Dialog with Inertia Navigation
import { Dialog, DialogContent, DialogHeader, DialogTitle } from '@/components/ui/dialog'
import { router } from '@inertiajs/react'
function UserDialog({ open, user }: { open: boolean; user: User }) {
return (
<Dialog
open={open}
onOpenChange={(isOpen) => {
if (!isOpen) {
router.replaceProp('show_dialog', false)
}
}}
>
<DialogContent>
<DialogHeader>
<DialogTitle>{user.name}</DialogTitle>
</DialogHeader>
{/* content */}
</DialogContent>
</Dialog>
)
}Table with Server-Side Sorting
shadcn <Table> renders normally. The Inertia-specific part is sorting via router.get:
const handleSort = (column: string) => {
router.get('/users', { sort: column }, { preserveState: true })
}
<TableHead onClick={() => handleSort('name')} className="cursor-pointer">
Name {sort === 'name' && '↑'}
</TableHead>Use <Link> (not <a>) for row links to preserve SPA navigation.
Toast with Flash Messages
Flash config (flash_keys) is in inertia-rails-controllers. Flash access (usePage().flash) is in inertia-rails-pages. This section covers toast UI wiring only.
MANDATORY — READ ENTIRE FILE when implementing flash-based toasts with Sonner: [references/flash-toast.md](references/flash-toast.md) (~80 lines) — full useFlash hook and Sonner toast provider. Do NOT load if only reading flash values without toast UI.
Key gotcha: flash_keys in the Rails initializer MUST match your FlashData TypeScript type — do NOT use success/error unless you also update both.
Dark Mode (No next-themes)
npx shadcn@latest init generates CSS variables for light/dark and @custom-variant dark (&:is(.dark *)); in your CSS (Tailwind v4). No extra setup needed for the variables themselves.
CRITICAL — prevent flash of wrong theme (FOUC): Next.js handles this automatically; Inertia does NOT. Add an inline script in <head> (before React hydrates) and call initializeTheme() in your Inertia entrypoint:
<%# app/views/layouts/application.html.erb — in <head>, before any stylesheets %>
<script>
document.documentElement.classList.toggle(
"dark",
localStorage.appearance === "dark" ||
(!("appearance" in localStorage) && window.matchMedia("(prefers-color-scheme: dark)").matches),
);
</script>// app/frontend/entrypoints/inertia.tsx
import { initializeTheme } from '@/hooks/use-appearance'
initializeTheme() // must run before createInertiaAppUse a useAppearance hook (light/dark/system modes, localStorage persistence, matchMedia listener) instead of next-themes. Toggle via .dark class on <html> — no provider needed.
Troubleshooting
| Symptom | Cause | Fix |
|---|---|---|
FormField/FormMessage crash |
Using shadcn form components that depend on react-hook-form | Replace with plain Input/Label + errors.field display |
Select value not submitted |
Missing name prop |
Add name="field" to <Select> — shadcn examples omit it |
| Dialog closes unexpectedly | Missing or wrong onOpenChange handler |
Use onOpenChange={(open) => { if (!open) closeHandler() }} |
| Flash of wrong theme (FOUC) | Missing inline <script> in <head> |
Add dark mode script before stylesheets (see Dark Mode section) |
Related Skills
- Form component →
inertia-rails-forms(<Form>render function, useForm) - Flash config →
inertia-rails-controllers(flash_keys initializer) - Flash access →
inertia-rails-pages(usePage().flash) - URL-driven dialogs →
inertia-rails-pages(router.get pattern)
References
Load [references/components.md](references/components.md) (~300 lines) when building shadcn components beyond those shown above (Accordion, Sheet, Tabs, DropdownMenu, AlertDialog with Inertia patterns).
Do NOT load components.md for basic Form, Select, Dialog, or Table usage — the examples above are sufficient.