EXAMPLE Ruby On Rails

bundle install

cp .env.example .env
# Edit .env and add your PostHog project token

bin/rails db:create db:migrate db:seed

bin/rails server

ruby-on-rails/
├── config/
│   ├── routes.rb                        # URL routing
│   └── initializers/
│       └── posthog.rb                   # PostHog + posthog-rails configuration
├── app/
│   ├── controllers/
│   │   ├── application_controller.rb    # Base controller with current_user
│   │   ├── sessions_controller.rb       # Login/logout with PostHog identify
│   │   ├── registrations_controller.rb  # Signup with PostHog identify
│   │   ├── dashboard_controller.rb      # Feature flags + ActiveJob demo
│   │   ├── burritos_controller.rb       # Custom event tracking
│   │   ├── profiles_controller.rb       # Page view tracking
│   │   └── errors_controller.rb         # Error tracking demos
│   ├── jobs/
│   │   └── example_job.rb              # ActiveJob auto-instrumentation demo
│   ├── models/
│   │   └── user.rb                     # posthog_distinct_id + posthog_properties
│   └── views/
│       ├── layouts/application.html.erb # Base layout with posthog-js snippet
│       ├── sessions/new.html.erb        # Login page
│       ├── registrations/new.html.erb   # Signup page
│       ├── dashboard/show.html.erb      # Feature flags demo
│       ├── burritos/show.html.erb       # Event tracking demo
│       └── profiles/show.html.erb       # Error tracking demo
├── db/
│   ├── migrate/                         # Database migrations
│   └── seeds.rb                         # Default admin user
├── .env.example                         # Environment variable template
├── Gemfile                              # Ruby dependencies
└── README.md                            # This file

# Rails-specific auto-instrumentation
PostHog::Rails.configure do |config|
  config.auto_capture_exceptions = true
  config.report_rescued_exceptions = true
  config.auto_instrument_active_job = true
  config.capture_user_context = true
  config.current_user_method = :current_user
  config.user_id_method = :posthog_distinct_id
end

PostHog.init do |config|
  config.api_key = ENV.fetch('POSTHOG_PROJECT_TOKEN', nil)
  config.host = ENV.fetch('POSTHOG_HOST', 'https://us.i.posthog.com')
end

class User < ApplicationRecord
  has_secure_password

  # Called by posthog-rails for automatic user association in error reports
  def posthog_distinct_id
    email
  end

  def posthog_properties
    { email: email, is_staff: is_staff, date_joined: created_at&.iso8601 }
  end
end

# Identify the user and capture login event
PostHog.identify(
  distinct_id: user.posthog_distinct_id,
  properties: user.posthog_properties
)

PostHog.capture(
  distinct_id: user.posthog_distinct_id,
  event: 'user_logged_in',
  properties: { login_method: 'email' }
)

# Check if a feature flag is enabled
@show_new_feature = PostHog.is_feature_enabled(
  'new-dashboard-feature',
  user.posthog_distinct_id,
  person_properties: user.posthog_properties
)

# Get feature flag payload for configuration
@feature_config = PostHog.get_feature_flag_payload(
  'new-dashboard-feature',
  user.posthog_distinct_id
)

# This exception is automatically captured by posthog-rails
# with the current_user's posthog_distinct_id attached
def show
  raise "Something went wrong"  # Captured automatically!
end

begin
  risky_operation
rescue => e
  PostHog.capture_exception(e, current_user.posthog_distinct_id)
end

# posthog-rails subscribes to Rails.error automatically
Rails.error.handle(context: { user_id: user.id }) do
  risky_operation
end

# config: auto_instrument_active_job = true
# Job failures are captured automatically.
# Use the posthog_distinct_id DSL to associate errors with a user.
class ExampleJob < ApplicationJob
  posthog_distinct_id ->(distinct_id, *) { distinct_id }

  def perform(distinct_id, should_fail: false)
    raise "Job failed"  # Captured automatically with user context
  end
end

# In the controller, pass the distinct_id when enqueuing:
ExampleJob.perform_later(current_user.posthog_distinct_id, should_fail: true)

# PostHog Configuration
POSTHOG_PROJECT_TOKEN=phc_your_project_token_here
POSTHOG_HOST=https://us.i.posthog.com

# Optional: Enable debug mode to see PostHog requests
# POSTHOG_DEBUG=true

class ApplicationController < ActionController::Base
  protect_from_forgery with: :exception

  private

  def current_user
    @current_user ||= User.find_by(id: session[:user_id]) if session[:user_id]
  end
  helper_method :current_user

  def require_login
    unless current_user
      redirect_to login_path
    end
  end
end

class BurritosController < ApplicationController
  before_action :require_login

  def show
    @burrito_count = session[:burrito_count] || 0
  end

  def consider
    count = (session[:burrito_count] || 0) + 1
    session[:burrito_count] = count

    user = current_user

    # PostHog: Track custom event
    PostHog.identify(
      distinct_id: user.posthog_distinct_id,
      properties: user.posthog_properties
    )

    PostHog.capture(
      distinct_id: user.posthog_distinct_id,
      event: 'burrito_considered',
      properties: { total_considerations: count }
    )

    render json: { success: true, count: count }
  end
end

class DashboardController < ApplicationController
  before_action :require_login

  def show
    user = current_user

    # PostHog: Track dashboard view
    PostHog.capture(
      distinct_id: user.posthog_distinct_id,
      event: 'dashboard_viewed',
      properties: { is_staff: user.is_staff }
    )

    # PostHog: Check feature flag
    @show_new_feature = PostHog.is_feature_enabled(
      'new-dashboard-feature',
      user.posthog_distinct_id,
      person_properties: user.posthog_properties
    )

    # PostHog: Get feature flag payload for configuration
    @feature_config = PostHog.get_feature_flag_payload(
      'new-dashboard-feature',
      user.posthog_distinct_id
    )
  end

  def enqueue_test_job
    # Enqueue a job that will fail — posthog-rails captures the error automatically.
    # The distinct_id is passed so the posthog_distinct_id DSL can associate the error with this user.
    ExampleJob.perform_later(current_user.posthog_distinct_id, should_fail: true)

    render json: {
      success: true,
      message: 'Job enqueued. The job will fail and posthog-rails will capture the error automatically.'
    }
  end
end

class ErrorsController < ApplicationController
  before_action :require_login

  def test
    # Manual exception capture — catch the error and report it explicitly
    begin
      raise StandardError, 'Test exception from critical operation'
    rescue StandardError => e
      # PostHog: Manually capture the exception
      PostHog.capture_exception(e, current_user.posthog_distinct_id)

      PostHog.capture(
        distinct_id: current_user.posthog_distinct_id,
        event: 'error_triggered',
        properties: {
          error_type: e.class.name,
          error_message: e.message
        }
      )

      render json: {
        success: false,
        error: e.message,
        message: 'Error has been captured by PostHog'
      }, status: :internal_server_error
    end
  end

  def test_rails_error
    # Rails.error.handle — Rails 7+ error reporting integration.
    # posthog-rails subscribes to Rails.error, so exceptions reported
    # via Rails.error.handle are automatically captured in PostHog.
    Rails.error.handle(context: { user_id: current_user.id }) do
      raise StandardError, 'Test error via Rails.error.handle — captured automatically by posthog-rails'
    end

    render json: {
      success: true,
      message: 'Error was handled via Rails.error.handle and captured by posthog-rails'
    }
  end
end

class ProfilesController < ApplicationController
  before_action :require_login

  def show
    # PostHog: Track profile view
    PostHog.capture(
      distinct_id: current_user.posthog_distinct_id,
      event: 'profile_viewed'
    )
  end
end

class RegistrationsController < ApplicationController
  def new
    redirect_to dashboard_path if current_user
  end

  def create
    user = User.new(
      email: params[:email],
      password: params[:password],
      password_confirmation: params[:password_confirmation]
    )

    if user.save
      session[:user_id] = user.id

      # PostHog: Identify the new user and capture signup event
      PostHog.identify(
        distinct_id: user.posthog_distinct_id,
        properties: user.posthog_properties
      )

      PostHog.capture(
        distinct_id: user.posthog_distinct_id,
        event: 'user_signed_up',
        properties: { signup_method: 'form' }
      )

      redirect_to dashboard_path
    else
      flash[:error] = user.errors.full_messages.join(', ')
      render :new, status: :unprocessable_entity
    end
  end
end

class SessionsController < ApplicationController
  def new
    redirect_to dashboard_path if current_user
  end

  def create
    user = User.find_by(email: params[:email])

    if user&.authenticate(params[:password])
      session[:user_id] = user.id

      # PostHog: Identify the user and capture login event
      PostHog.identify(
        distinct_id: user.posthog_distinct_id,
        properties: user.posthog_properties
      )

      PostHog.capture(
        distinct_id: user.posthog_distinct_id,
        event: 'user_logged_in',
        properties: { login_method: 'email' }
      )

      redirect_to dashboard_path
    else
      flash[:error] = 'Invalid email or password'
      render :new, status: :unprocessable_entity
    end
  end

  def destroy
    if current_user
      # PostHog: Track logout before session ends
      PostHog.capture(
        distinct_id: current_user.posthog_distinct_id,
        event: 'user_logged_out'
      )
    end

    session.delete(:user_id)
    redirect_to login_path
  end
end

class ApplicationJob < ActiveJob::Base
end

# Example ActiveJob demonstrating posthog-rails auto-instrumentation.
#
# When auto_instrument_active_job is enabled in the PostHog config,
# posthog-rails automatically captures exceptions from failed jobs.
# The job class name, queue, and arguments are included as properties
# on the error event.
#
# Use the posthog_distinct_id DSL to associate job errors with a user.
# The proc receives the same arguments as perform and should return
# the distinct_id string. Without this, job errors have no user context.
class ExampleJob < ApplicationJob
  queue_as :default

  # Extract distinct_id from the first argument so posthog-rails
  # can associate the error with the user who triggered the job.
  posthog_distinct_id ->(distinct_id, *) { distinct_id }

  def perform(distinct_id, should_fail: false)
    if should_fail
      raise StandardError, 'Example job failure - this error is automatically captured by posthog-rails'
    end

    Rails.logger.info "ExampleJob completed successfully for #{distinct_id}"
  end
end

class ApplicationRecord < ActiveRecord::Base
  primary_abstract_class
end

class User < ApplicationRecord
  has_secure_password

  validates :email, presence: true, uniqueness: true

  # Called by posthog-rails for automatic user association in error reports.
  # When auto_capture_exceptions and capture_user_context are enabled,
  # posthog-rails calls this method on current_user to get the distinct_id.
  def posthog_distinct_id
    email
  end

  # Helper used by controllers when calling PostHog.identify to set person properties.
  # These properties appear on the person profile in PostHog.
  def posthog_properties
    {
      email: email,
      is_staff: is_staff,
      date_joined: created_at&.iso8601
    }
  end
end

<% content_for(:title) { 'Burrito - PostHog Rails example' } %>

<div class="card">
    <h1>Burrito consideration tracker</h1>
    <p>This page demonstrates custom event tracking with PostHog.</p>
</div>

<div class="card" style="text-align: center;">
    <h2>Times considered</h2>
    <div class="count" id="burrito-count"><%= @burrito_count %></div>
    <button onclick="considerBurrito()" style="font-size: 18px; padding: 15px 30px;">
        Consider a burrito
    </button>
</div>

<div class="card">
    <h3>How event tracking works</h3>
    <p>Each time you click the button, a <code>burrito_considered</code> event is sent to PostHog:</p>
    <pre style="background: #f3f4f6; padding: 15px; border-radius: 5px; overflow-x: auto; margin-top: 15px;"><code>PostHog.capture(
  distinct_id: user.posthog_distinct_id,
  event: 'burrito_considered',
  properties: { total_considerations: count }
)</code></pre>
</div>

<% content_for :scripts do %>
<script>
async function considerBurrito() {
    try {
        const response = await fetch('/api/burrito/consider', {
            method: 'POST',
            headers: {
                'X-CSRF-Token': document.querySelector('meta[name="csrf-token"]').content,
                'Content-Type': 'application/json',
            },
        });

        const data = await response.json();

        if (data.success) {
            document.getElementById('burrito-count').textContent = data.count;
        }
    } catch (error) {
        console.error('Error:', error);
    }
}
</script>
<% end %>

<% content_for(:title) { 'Dashboard - PostHog Rails example' } %>

<div class="card">
    <h1>Dashboard</h1>
    <p>Welcome back, <strong><%= current_user.email %></strong>!</p>
</div>

<div class="card">
    <h2>Feature flags</h2>
    <p>Feature flags allow you to control feature rollouts and run A/B tests.</p>

    <% if @show_new_feature %>
    <div class="feature-flag">
        <h3>New feature enabled!</h3>
        <p>
            This section is only visible because the <code>new-dashboard-feature</code>
            flag is enabled for your user.
        </p>
        <% if @feature_config %>
        <p><strong>Feature config:</strong> <%= @feature_config %></p>
        <% end %>
    </div>
    <% else %>
    <div style="background: #f3f4f6; padding: 15px; border-radius: 8px; margin-top: 15px;">
        <p>
            The <code>new-dashboard-feature</code> flag is not enabled for your user.
            Create this flag in your PostHog project to see it in action.
        </p>
    </div>
    <% end %>
</div>

<div class="card">
    <h2>ActiveJob instrumentation</h2>
    <p>
        Click below to enqueue a background job that will fail.
        <code>posthog-rails</code> automatically captures the exception — no extra code needed.
    </p>
    <button onclick="enqueueTestJob()" style="margin-top: 10px;">Enqueue failing job</button>
    <div id="job-result" style="margin-top: 15px; display: none;"></div>
</div>

<div class="card">
    <h3>How feature flags work</h3>
    <pre style="background: #f3f4f6; padding: 15px; border-radius: 5px; overflow-x: auto;"><code># Check if a feature flag is enabled
show_feature = PostHog.is_feature_enabled(
  'new-dashboard-feature',
  user.posthog_distinct_id,
  person_properties: user.posthog_properties
)

# Get feature flag payload for configuration
config = PostHog.get_feature_flag_payload(
  'new-dashboard-feature',
  user.posthog_distinct_id
)</code></pre>
</div>

<% content_for :scripts do %>
<script>
async function enqueueTestJob() {
    const resultDiv = document.getElementById('job-result');
    try {
        const response = await fetch('/api/test-job', {
            method: 'POST',
            headers: {
                'X-CSRF-Token': document.querySelector('meta[name="csrf-token"]').content,
                'Content-Type': 'application/json',
            },
        });
        const data = await response.json();
        resultDiv.style.display = 'block';
        resultDiv.innerHTML = '<div class="flash success">' + data.message + '</div>';
    } catch (error) {
        resultDiv.style.display = 'block';
        resultDiv.innerHTML = '<div class="flash error">Request failed: ' + error + '</div>';
    }
}
</script>
<% end %>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title><%= content_for?(:title) ? yield(:title) : 

<% content_for(:title) { 'Profile - PostHog Rails example' } %>

<div class="card">
    <h1>Profile</h1>
    <p>This page demonstrates error tracking with PostHog and <code>posthog-rails</code>.</p>
</div>

<div class="card">
    <h2

<% content_for(:title) { 'Sign Up - PostHog Rails example' } %>

<div class="card">
    <h1>Sign Up</h1>
    <p>Create an account to see PostHog analytics in action.</p>

    <form action="<%= signup_path %>" method="post" style="margin-top: 20px;">
        <%= hidden_field_tag :authenticity_token, form_authenticity_token %>
        <input type="email" name="email" placeholder="Email" required>
        <input type="password" name="password" placeholder="Password" required>
        <input type="password" name="password_confirmation" placeholder="Confirm Password" required>
        <button type="submit">Sign Up</button>
    </form>

    <p style="margin-top: 15px; color: #666; font-size: 14px;">
        Already have an account? <a href="<%= login_path %>">Login</a>
    </p>
</div>

<% content_for(:title) { 'Login - PostHog Rails example' } %>

<div class="card">
    <h1>PostHog Rails example</h1>
    <p>Welcome! This example demonstrates PostHog integration with Ruby on Rails, including automatic error tracking via <code>posthog-rails</code>.</p>
</div>

<div class="card">
    <h2>Login</h2>
    <p>Login to see PostHog analytics in action.</p>

    <form action="<%= login_path %>" method="post" style="margin-top: 20px;">
        <%= hidden_field_tag :authenticity_token, form_authenticity_token %>
        <input type="email" name="email" placeholder="Email" required>
        <input type="password" name="password" placeholder="Password" required>
        <button type="submit">Login</button>
    </form>

    <p style="margin-top: 15px; color: #666; font-size: 14px;">
        Don't have an account? <a href="<%= signup_path %>">Sign up</a><br>
        Tip: Run <code>bin/rails db:seed</code> to create admin@example.com / admin
    </p>
</div>

<div class="card">
    <h3>What this example demonstrates</h3>
    <ul style="padding-left: 20px;">
        <li><strong>User identification</strong> — Users are identified with <code>PostHog.identify</code> on login</li>
        <li><strong>Event tracking</strong> — Custom events captured with <code>PostHog.capture</code></li>
        <li><strong>Feature flags</strong> — Conditional features with <code>PostHog.is_feature_enabled</code></li>
        <li><strong>Error tracking (auto)</strong> — Unhandled exceptions captured automatically by <code>posthog-rails</code></li>
        <li><strong>Error tracking (manual)</strong> — Handled errors captured with <code>PostHog.capture_exception</code></li>
        <li><strong>ActiveJob instrumentation</strong> — Background job failures captured automatically</li>
        <li><strong>Rails.error integration</strong> — Rails 7+ error reporting captured by <code>posthog-rails</code></li>
        <li><strong>Frontend tracking</strong> — posthog-js captures pageviews and session replay</li>
    </ul>
</div>

require_relative 'config/environment'
run Rails.application

require_relative 'boot'
require 'rails/all'

Bundler.require(*Rails.groups)

module PosthogExample
  class Application < Rails::Application
    config.load_defaults 7.1

    # Use SQLite for all stores
    config.active_job.queue_adapter = :async
  end
end

ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../Gemfile', __dir__)

require 'bundler/setup'

require_relative 'application'
Rails.application.initialize!

require 'active_support/core_ext/integer/time'

Rails.application.configure do
  config.enable_reloading = true
  config.eager_load = false
  config.consider_all_requests_local = true
  config.server_timing = true

  # Secret key for development (not used in production)
  config.secret_key_base = 'dev-secret-key-for-posthog-example-only'

  config.action_controller.perform_caching = false
  config.cache_store = :memory_store

  config.active_support.deprecation = :log
  config.active_support.disallowed_deprecation = :raise
  config.active_support.disallowed_deprecation_warnings = []

  config.active_record.migration_error = :page_load
  config.active_record.verbose_query_logs = true
end

# PostHog configuration with posthog-rails auto-instrumentation
#
# The posthog-rails gem provides:
# - Automatic exception capture for unhandled controller errors
# - ActiveJob instrumentation for background job failures
# - User context detection from current_user
# - Rails.error integration for rescued exceptions 
PostHog.init do |config|
  config.api_key = ENV.fetch('POSTHOG_PROJECT_TOKEN', nil)
  config.host = ENV.fetch('POSTHOG_HOST', 'https://us.i.posthog.com')
end

PostHog::Rails.configure do |config|
  # Auto-capture unhandled exceptions in controllers
  config.auto_capture_exceptions = true

  # Also capture exceptions that Rails rescues (e.g. ActiveRecord::RecordNotFound)
  config.report_rescued_exceptions = true

  # Auto-instrument ActiveJob failures
  config.auto_instrument_active_job = true

  # Automatically associate errors with the current user
  config.capture_user_context = true
  config.current_user_method = :current_user
  config.user_id_method = :posthog_distinct_id
end

Rails.application.routes.draw do
  # Auth
  get 'login', to: 'sessions#new'
  post 'login', to: 'sessions#create'
  delete 'logout', to: 'sessions#destroy'

  get 'signup', to: 'registrations#new'
  post 'signup', to: 'registrations#create'

  # App
  get 'dashboard', to: 'dashboard#show'
  get 'burrito', to: 'burritos#show'
  post 'api/burrito/consider', to: 'burritos#consider'
  get 'profile', to: 'profiles#show'

  # Error tracking demos
  post 'api/test-error', to: 'errors#test'
  post 'api/test-rails-error', to: 'errors#test_rails_error'

  # Background job demo
  post 'api/test-job', to: 'dashboard#enqueue_test_job'

  root 'sessions#new'
end

class CreateUsers < ActiveRecord::Migration[7.1]
  def change
    create_table :users do |t|
      t.string :email, null: false
      t.string :password_digest, null: false
      t.boolean :is_staff, default: false

      t.timestamps
    end

    add_index :users, :email, unique: true
  end
end

# This file is auto-generated from the current state of the database. Instead
# of editing this file, please use the migrations feature of Active Record to
# incrementally modify your database, and then regenerate this schema definition.
#
# This file is the source Rails uses to define your schema when running `bin/rails
# db:schema:load`. When creating a new database, `bin/rails db:schema:load` tends to
# be faster and is potentially less error prone than running all of your
# migrations from scratch. Old migrations may fail to apply correctly if those
# migrations use external dependencies or application code.
#
# It's strongly recommended that you check this file into your version control system.

ActiveRecord::Schema[7.2].define(version: 2024_01_01_000000) do
  create_table "users", force: :cascade do |t|
    t.string "email", null: false
    t.string "password_digest", null: false
    t.boolean "is_staff", default: false
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.index ["email"], name: "index_users_on_email", unique: true
  end
end

# Create a default admin user for testing
User.find_or_create_by!(email: 'admin@example.com') do |user|
  user.password = 'admin'
  user.password_confirmation = 'admin'
  user.is_staff = true
end

puts 'Seed data created: admin@example.com / admin'

source 'https://rubygems.org'

gem 'rails', '~> 7.1'
gem 'sqlite3', '~> 1.7'
gem 'puma', '~> 6.0'
gem 'bcrypt', '~> 3.1'
gem 'dotenv-rails', '~> 3.0'

# PostHog
gem 'posthog-ruby', '~> 3.0'
gem 'posthog-rails'

require_relative 'config/application'
Rails.application.load_tasks