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igmarin/elixir-phoenix-skills

Curated library of 38 atomic skills, 7 personas, and 1 orchestrator for Elixir and Phoenix development. Organized by category: fundamentals, phoenix, database, testing, auth, infrastructure, quality, security, integrations, tooling, frameworks, personas, and orchestration. Covers core Elixir patterns, Phoenix LiveView, Ecto, OTP, Oban, testing, security, deployment, real-time, and modern tooling (Req, Swoosh, Cachex, Broadway, Ash).

73

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91%

Does it follow best practices?

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Overview
Quality
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Files

SKILL.mdskills/auth/phoenix-auth-customization/

name:
phoenix-auth-customization
type:
atomic
tags:
atomic
license:
MIT
description:
MANDATORY when extending phx.gen.auth with custom fields. Invoke before adding usernames, profiles, or custom registration fields. Covers migrations, schema updates, fixture updates, form changes, and confirmation patterns. Trigger words: phx.gen.auth, custom fields, registration, username, profile, auth customization.
metadata:
{"user-invocable":"true","version":"1.0.0","adapted-from":"j-morgan6/elixir-phoenix-guide","original-author":"Joseph Morgan"}

Phoenix Auth Customization

Use this skill when extending phx.gen.auth with custom fields.

RULES — Follow these with no exceptions

  1. Never modify generated auth migrations — create separate migrations for custom fields
  2. Update registration_changeset to cast and validate new fields — don't create a separate changeset
  3. Update test fixtures when adding required fields — missing fixture fields cause cryptic test failures
  4. Confirm users in test fixtures for password-based auth — set confirmed_at or tests will fail
  5. Update both the registration form AND the save/2 handler — the form must send the field
  6. Use unique_constraint + database unique index for uniqueness — never validate in application code alone

Running phx.gen.auth

# Generate auth with LiveView (recommended)
mix phx.gen.auth Accounts User users

Adding Custom Fields

Step 1: Create a Separate Migration

mix ecto.gen.migration add_username_to_users
defmodule MyApp.Repo.Migrations.AddUsernameToUsers do
  use Ecto.Migration

  def change do
    alter table(:users) do
      add :username, :string, null: false
    end

    create unique_index(:users, [:username])
  end
end
# Run migration and verify success before proceeding
mix ecto.migrate

Step 2: Update the Schema

defmodule MyApp.Accounts.User do
  schema "users" do
    field :email, :string
    field :username, :string  # Add new field
    field :password, :string, virtual: true, redact: true
    field :hashed_password, :string, redact: true
    field :confirmed_at, :utc_datetime

    timestamps()
  end

  # Update registration_changeset to include username
  def registration_changeset(user, attrs, opts \\ []) do
    user
    |> cast(attrs, [:email, :username, :password])
    |> validate_required([:username])
    |> validate_username()
    |> validate_email(opts)
    |> validate_password(opts)
  end

  defp validate_username(changeset) do
    changeset
    |> validate_required([:username])
    |> validate_format(:username, ~r/^[a-zA-Z0-9_]+$/,
      message: "only letters, numbers, and underscores"
    )
    |> validate_length(:username, min: 3, max: 30)
    |> unsafe_validate_unique(:username, MyApp.Repo)
    |> unique_constraint(:username)
  end
end

Step 3: Update Test Fixtures

def user_fixture(attrs \\ %{}) do
  {:ok, user} =
    attrs
    |> Enum.into(%{
      email: "user#{System.unique_integer([:positive])}@example.com",
      username: "user#{System.unique_integer([:positive])}",  # Add username
      password: "hello world!",
      confirmed_at: DateTime.utc_now(:second)  # Confirm for tests
    })
    |> MyApp.Accounts.register_user()

  user
end
# Verify fixtures pass before updating forms
mix test

Step 4: Update the Registration Form

<.simple_form for={@form} phx-change="validate" phx-submit="save">
  <.input field={@form[:username]} type="text" label="Username" />
  <.input field={@form[:email]} type="email" label="Email" />
  <.input field={@form[:password]} type="password" label="Password" />

  <:actions>
    <.button>Register</.button>
  </:actions>
</.simple_form>

skills

auth

phoenix-auth-customization

SKILL.md

README.md

tile.json