Inertia Rails Setup

This skill helps you set up Inertia.js in a Ruby on Rails application with your choice of frontend framework.

Recommended: Official Starter Kits

For new projects, the fastest way to get started is cloning an official starter kit. These include authentication, shadcn/ui components, TypeScript, and optional SSR support out of the box.

React Starter Kit (Recommended)

git clone https://github.com/inertia-rails/react-starter-kit myapp
cd myapp
bin/setup

Includes:

React 19 + TypeScript
shadcn/ui component library (20+ components)
User authentication (login, register, password reset)
Settings pages (profile, password, email, sessions, appearance)
Multiple layouts (sidebar, header, auth variants)
Dark mode support
Kamal deployment config
Optional SSR support
Flash messages with Sonner toasts

Vue Starter Kit

git clone https://github.com/inertia-rails/vue-starter-kit myapp
cd myapp
bin/setup

Svelte Starter Kit

git clone https://github.com/inertia-rails/svelte-starter-kit myapp
cd myapp
bin/setup

Customizing the Starter Kit

After cloning:

Rename the app:

``bash # Update config/application.rb module YourAppName class Application < Rails::Application ``

Update database config:

``bash # Edit config/database.yml with your settings ``

Remove example pages you don't need:

``bash # Delete from app/frontend/pages/ and corresponding controllers ``

Add your own pages:

``bash bin/rails generate controller Products index show # Create app/frontend/pages/products/index.tsx ``

Customize the layout:

- Edit app/frontend/layouts/app-layout.tsx for main app - Edit app/frontend/components/nav-main.tsx for navigation

Alternative: Generator Setup

If you prefer starting from scratch or adding Inertia to an existing Rails app:

Quick Setup

# Create new Rails app (if needed)
rails new myapp --skip-javascript

# Add inertia_rails gem
bundle add inertia_rails

# Run the generator
bin/rails generate inertia:install

The generator will prompt you to select:

Frontend framework (React, Vue, or Svelte)
TypeScript support
Tailwind CSS integration

Manual Setup Steps

1. Add the Gem

# Gemfile
gem 'inertia_rails'

bundle install

2. Install Vite Rails (if not present)

bundle add vite_rails
bundle exec vite install

3. Configure the Root Layout

Create or update app/views/layouts/application.html.erb:

<!DOCTYPE html>
<html>
  <head>
    <meta name="viewport" content="width=device-width,initial-scale=1">
    <%= csp_meta_tag %>
    <%= inertia_ssr_head %>
    <%= vite_client_tag %>
    <%= vite_javascript_tag 'application' %>
  </head>
  <body>
    <%= yield %>
  </body>
</html>

4. Install Frontend Dependencies

For React:

npm install @inertiajs/react @inertiajs/vite react react-dom

For Vue 3:

npm install @inertiajs/vue3 @inertiajs/vite vue

For Svelte:

npm install @inertiajs/svelte @inertiajs/vite svelte

5. Configure the Frontend Entry Point

Create app/frontend/entrypoints/application.js:

React:

import { createInertiaApp } from '@inertiajs/react'
import { createRoot } from 'react-dom/client'
import { inertia } from '@inertiajs/vite'

createInertiaApp({
  resolve: inertia.resolvePages('../pages'),
  setup({ el, App, props }) {
    createRoot(el).render(<App {...props} />)
  },
})

Vue 3:

import { createApp, h } from 'vue'
import { createInertiaApp } from '@inertiajs/vue3'
import { inertia } from '@inertiajs/vite'

createInertiaApp({
  resolve: inertia.resolvePages('../pages'),
  setup({ el, App, props, plugin }) {
    createApp({ render: () => h(App, props) })
      .use(plugin)
      .mount(el)
  },
})

Svelte:

import { createInertiaApp } from '@inertiajs/svelte'
import { inertia } from '@inertiajs/vite'

createInertiaApp({
  resolve: inertia.resolvePages('../pages'),
  setup({ el, App }) {
    new App({ target: el })
  },
})

6. Create the Pages Directory

mkdir -p app/frontend/pages

7. Configure the Initializer

Create config/initializers/inertia_rails.rb:

# frozen_string_literal: true

InertiaRails.configure do |config|
  # Asset versioning
  config.version = -> { ViteRuby.digest }

  # Flash keys exposed to frontend
  config.flash_keys = %i[notice alert]

  # Required for Inertia.js v3
  config.use_script_element_for_initial_page = true
  config.use_data_inertia_head_attribute = true
  config.always_include_errors_hash = true

  # Deep merge shared data with page props
  # config.deep_merge_shared_data = true

  # Encrypt history for sensitive data (requires HTTPS)
  # config.encrypt_history = Rails.env.production?
end

8. Set Up Shared Data

In app/controllers/application_controller.rb:

class ApplicationController < ActionController::Base
  inertia_share do
    {
      flash: {
        notice: flash.notice,
        alert: flash.alert
      },
      auth: {
        user: current_user&.as_json(only: [:id, :name, :email])
      }
    }
  end
end

9. Create Your First Page

Controller:

# app/controllers/home_controller.rb
class HomeController < ApplicationController
  def index
    render inertia: { message: 'Welcome to Inertia Rails!' }
  end
end

Route:

# config/routes.rb
Rails.application.routes.draw do
  root 'home#index'
end

Page Component (React):

// app/frontend/pages/home/index.jsx
export default function Home({ message }) {
  return (
    <div>
      <h1>{message}</h1>
    </div>
  )
}

Page Component (Vue):

<!-- app/frontend/pages/home/index.vue -->
<script setup>
defineProps(['message'])
</script>

<template>
  <div>
    <h1>{{ message }}</h1>
  </div>
</template>

10. Start the Development Servers

# Terminal 1: Rails server
bin/rails server

# Terminal 2: Vite dev server
bin/vite dev

Configuration Options Reference

Option	Default	Description
`version`	`nil`	Asset version for cache busting
`layout`	`'application'`	Default layout template
`flash_keys`	`[:notice, :alert]`	Flash keys to share
`deepmergeshared_data`	`false`	Deep merge props
`encrypt_history`	`false`	Encrypt browser history
`ssr_enabled`	`false`	Enable SSR
`ssr_url`	`'http://localhost:13714';`	SSR server URL
`default_render`	`false`	Auto-render Inertia
`rootdomid`	`'app'`	Root element ID
`usescriptelementforinitial_page`	`false`	Use `<script>` tag for initial page data (required for v3)
`usedatainertiaheadattribute`	`false`	Use `data-inertia` attribute for head tags (required for v3)
`alwaysincludeerrors_hash`	`nil`	Always include errors object in page props
`prop_transformer`	identity	Transform prop keys (e.g., camelCase)
`componentpathresolver`	`"path/action"`	Custom component name resolution
`parent_controller`	`'::ApplicationController'`	Base controller for static routes
`exposesharedprop_keys`	`true`	Include shared prop keys in page metadata
`precognitionpreventwrites`	`false`	Prevent DB writes during precognition

Environment Variables

All config options can be set via INERTIA_ prefixed env vars:

INERTIA_SSR_ENABLED=true
INERTIA_ENCRYPT_HISTORY=true

Upgrading to Inertia.js v3

If upgrading an existing Inertia.js v2 project:

Required Configuration Changes

Add these to your Inertia Rails initializer:

config.use_script_element_for_initial_page = true
config.use_data_inertia_head_attribute = true
config.always_include_errors_hash = true

Breaking Changes

React 19+ required
Svelte 5+ with runes syntax required
ES2022 build target required
ESM-only — no CommonJS
Axios removed — uses built-in XHR (use axiosAdapter() to keep Axios)
Event renames: invalid → httpException, exception → networkError
router.cancel() → router.cancelAll()
Head attribute: inertia → data-inertia

Install the Vite Plugin

npm install @inertiajs/vite

Update vite.config.js:

import inertia from '@inertiajs/vite'

export default defineConfig({
  plugins: [
    inertia(),
    // ... other plugins
  ],
})

The Vite plugin provides:

Automatic page component resolution
Simplified SSR setup (no separate entry point in development)
withApp callback for providers/plugins

Troubleshooting

"Cannot find module '@inertiajs/react'"

Run npm install to install dependencies.

Blank page with no errors

Check browser console for JavaScript errors. Ensure Vite dev server is running.

Props not updating

Ensure you're using render inertia: not render json:.

CSRF token errors

Inertia handles CSRF automatically. Ensure protectfromforgery is enabled.

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