Phoenix Development

Full-stack guidance for production Phoenix + LiveView applications. Covers the Elixir language layer, Phoenix framework conventions, Ecto data access, LiveView interactivity, HEEx templating, forms, and testing.

For API contract design and HTTP semantics, see /api-design. For domain modeling and schema evolution, see /domain-design. For responsive CSS and Tailwind v4, see /css-responsive. For design system and accessibility, see /ux-design. For observability, see /observability.

1. Elixir Idioms

• Variables are immutable but rebindable — block expressions (if, case, cond) must bind their result to use it:

  # WRONG — rebinding inside `if` has no effect outside
  if connected?(socket), do: socket = assign(socket, :val, val)
  
  # RIGHT — bind the block result
  socket = if connected?(socket), do: assign(socket, :val, val), else: socket