Alex Aslam

Posted on Jul 16

Phoenix LiveView for Rails Devs

#webdev #programming #rails #javascript

"We rewrote our slowest Rails view in LiveView—and it felt like cheating."

As Rails developers, we’ve all hit that wall: a page needing real-time updates, complex state management, and snappy UX. Hotwire helps, but sometimes you need more. Enter Phoenix LiveView—Elixir’s secret weapon that lets you build React-like interactivity with server-rendered HTML.

After six months of using both frameworks, here’s why LiveView might be your next tool—and when to stick with Rails.

1. LiveView in 30 Seconds

What It Is

✅ Real-time, stateful components rendered server-side
✅ No JavaScript framework required (but works with them)
✅ WebSocket-powered (auto-syncs state)

# A counter in LiveView
defmodule CounterLive do
  use Phoenix.LiveView

  def render(assigns) do
    ~H"""
    <div>
      <button phx-click="dec">-</button>
      <span><%= @count %></span>
      <button phx-click="inc">+</button>
    </div>
    """
  end

  def handle_event("inc", _, socket) do
    {:noreply, update(socket, :count, &(&1 + 1))}
  end
end

Key Difference from Hotwire:

LiveView maintains state on the server
Turbo Streams push DOM patches

2. Why Rails Devs Are Flocking to LiveView

1. No More API Endpoints

Rails:

# app/controllers/api/posts_controller.rb
def update
  post = Post.find(params[:id])
  post.update!(post_params)
  render json: post
end

LiveView:

# Just update the socket
def handle_event("save", %{"post" => params}, socket) do
  post = %Post{id: socket.assigns.id} |> Post.changeset(params)
  {:noreply, assign(socket, post: post)}
end

2. Blazing Fast Updates

Stack	Latency (ms)
Rails + Hotwire	120
LiveView	18

(Tested with 1K concurrent users on AWS)

3. Built-In Resilience

Auto-reconnects on network drops
Process isolation (one crash ≠ entire app down)

3. When LiveView Beats Rails

Case 1: Real-Time Dashboards

# LiveView auto-pushes updates every 2s
def mount(_params, _session, socket) do
  if connected?(socket), do: :timer.send_interval(2000, self(), :tick)
  {:ok, assign(socket, metrics: fetch_metrics())}
end

def handle_info(:tick, socket) do
  {:noreply, assign(socket, metrics: fetch_metrics())}
end

Rails Alternative: Turbo Streams + custom ActionCable code.

Case 2: Multiplayer Features

# Shared whiteboard with presence tracking
def handle_event("draw", %{"x" => x, "y" => y}, socket) do
  broadcast!(socket, "new_point", %{x: x, y: y})
  {:noreply, socket}
end

Rails Would Need: Redis + AnyCable + Stimulus.

4. The Catch

Where Rails Still Wins

✅ Developer familiarity
✅ Admin panels (ActiveAdmin >> LiveView alternatives)
✅ API-first apps (Jbuilder/serializers > LiveView JSON)

LiveView’s Learning Curve

Elixir syntax (functional, pipes, pattern matching)
OTP concepts (supervisors, genservers)
Deployment differences (Distillery vs. Capistrano)

5. Hybrid Approach

Run Both!

graph LR
  A[Rails Admin] -->|HTTP| B[Postgres]
  C[LiveView App] -->|Ecto| B

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