Error Pages (#331)

* Beacon install integration test

* Test data_source, mixfile, seeds

* Credo

* Fixes

* Bump tailwind version

* Idempotence tests

* Update template

* Resolve compile warnings

* Schema

* Context functions

* Migration

* Update docs

* Inject in mix task

* Test

* Error pages backend

* Minor fixes

* Fix typespec

* Unique index

* Add test for create error

* Use error layout

* Small doc fixes

* Validate error status codes

* Switch error pages to module recompilation

* CI fixes

* Fix test fixtures

* render

* test render/1

* publish default layouts

* Improve test fixture

* Test custom error page

* PubSub

* Still not working

* render error page with root layout

compile a function for each part of the layout tree: root, layout, and page
where root takes the content of page+layout

* fix layout path

* pass @conn to root_layout

* test ErrorHTML

* Check render and layout for my_component

* fix tests and cleanup

* add logger when error page render fails

* use Phoenix.HTML.Engine

* add tests rendering my_component

* remove support for components in error pages

It's possible to load those but requires injecting the LivePage env,
which is risky because a server error may happen due to internals or even
due to the components used in the pages, causing an endless loop.
So for now we won't load components due to the risk they impose but we can
revisit this if needed or if we find a safer approach.

* broadcast error_page_updated event only on update_error_page/2

* fix dialyzer

* fix dialyzer 2

* compile error page content and reload css

---------

Co-authored-by: Leandro Pereira <leandro@leandro.io>

dev.exs

@@ -17,12 +17,15 @@ Logger.configure(level: :debug)
 
 Application.put_env(:phoenix, :json_library, Jason)
 
+display_error_pages? = false
+
 Application.put_env(:beacon, SamplePhoenix.Endpoint,
   http: [ip: {127, 0, 0, 1}, port: 4001],
   server: true,
   live_view: [signing_salt: "aaaaaaaa"],
   secret_key_base: String.duplicate("a", 64),
-  debug_errors: true,
+  debug_errors: !display_error_pages?,
+  render_errors: [formats: [html: BeaconWeb.ErrorHTML]],
   check_origin: false,
   pubsub_server: SamplePhoenix.PubSub,
   live_reload: [

lib/beacon/content.ex

@@ -26,6 +26,7 @@ defmodule Beacon.Content do
   import Ecto.Query
 
   alias Beacon.Content.Component
+  alias Beacon.Content.ErrorPage
   alias Beacon.Content.Layout
   alias Beacon.Content.LayoutEvent
   alias Beacon.Content.LayoutSnapshot
@@ -47,7 +48,7 @@ defmodule Beacon.Content do
   @doc """
   Returns the list of meta tags that are applied to all pages by default.
 
-  These meta tags can be overwriten or extended on a Layout or Page level.
+  These meta tags can be overwritten or extended on a Layout or Page level.
   """
   @spec default_site_meta_tags() :: [map()]
   def default_site_meta_tags do
@@ -73,6 +74,18 @@ defmodule Beacon.Content do
     Layout.changeset(layout, attrs)
   end
 
+  @doc """
+  Returns a map of attrs to load the default layout into new sites.
+  """
+  @spec default_layout() :: map()
+  @doc type: :layouts
+  def default_layout do
+    %{
+      title: "Default",
+      template: "<%= @inner_content %>"
+    }
+  end
+
   @doc """
   Creates a layout.
 
@@ -1675,7 +1688,7 @@ defmodule Beacon.Content do
 
   Note that the `:page` assigns is made available as `assigns["page"]` (String.t) due to how Solid works.
 
-  Snipets can be used in:
+  Snippets can be used in:
 
     * Meta Tag value
     * Page Schema (structured Schema.org tags)
@@ -1704,6 +1717,137 @@ defmodule Beacon.Content do
     end
   end
 
+  # ERROR PAGES
+
+  @doc """
+  Returns an `%Ecto.Changeset{}` for tracking error page changes.
+
+  ## Example
+
+      iex> change_error_page(error_page, %{status: 404})
+      %Ecto.Changeset{data: %ErrorPage{}}
+
+  """
+  @doc type: :error_pages
+  @spec change_error_page(ErrorPage.t(), map()) :: Changeset.t()
+  def change_error_page(%ErrorPage{} = error_page, attrs \\ %{}) do
+    ErrorPage.changeset(error_page, attrs)
+  end
+
+  @doc """
+  Returns the error page for a given site and status code, or `nil` if no matching error page exists.
+  """
+  @doc type: :error_pages
+  @spec get_error_page(Site.t(), ErrorPage.error_status()) :: ErrorPage.t() | nil
+  def get_error_page(site, status) do
+    Repo.one(
+      from e in ErrorPage,
+        where: e.site == ^site,
+        where: e.status == ^status
+    )
+  end
+
+  @doc """
+  Lists all error pages for a given site.
+
+  ## Options
+
+    * `:per_page` - limit how many records are returned, or pass `:infinity` to return all records.
+    * `:preloads` - a list of preloads to load.
+
+  """
+  @doc type: :error_pages
+  @spec list_error_pages(Site.t(), keyword()) :: [ErrorPage.t()]
+  def list_error_pages(site, opts \\ []) do
+    per_page = Keyword.get(opts, :per_page, 20)
+    preloads = Keyword.get(opts, :preloads, [])
+
+    site
+    |> query_list_error_pages_base()
+    |> query_list_error_pages_limit(per_page)
+    |> query_list_error_pages_preloads(preloads)
+    |> Repo.all()
+  end
+
+  defp query_list_error_pages_base(site) do
+    from p in ErrorPage,
+      where: p.site == ^site,
+      order_by: [asc: p.status]
+  end
+
+  defp query_list_error_pages_limit(query, limit) when is_integer(limit), do: from(q in query, limit: ^limit)
+  defp query_list_error_pages_limit(query, :infinity = _limit), do: query
+  defp query_list_error_pages_limit(query, _per_page), do: from(q in query, limit: 20)
+
+  defp query_list_error_pages_preloads(query, [_preload | _] = preloads) do
+    from(q in query, preload: ^preloads)
+  end
+
+  defp query_list_error_pages_preloads(query, _preloads), do: query
+
+  @doc """
+  Creates a new error page.
+  """
+  @doc type: :error_pages
+  @spec create_error_page(%{site: Site.t(), status: ErrorPage.error_status(), template: binary(), layout_id: Ecto.UUID.t()}) ::
+          {:ok, ErrorPage.t()} | {:error, Changeset.t()}
+  def create_error_page(attrs) do
+    %ErrorPage{}
+    |> ErrorPage.changeset(attrs)
+    |> Repo.insert()
+  end
+
+  @doc """
+  Creates a new error page, raising if the operation fails.
+  """
+  @doc type: :error_pages
+  @spec create_error_page!(%{site: Site.t(), status: ErrorPage.error_status(), template: binary(), layout_id: Ecto.UUID.t()}) ::
+          ErrorPage.t()
+  def create_error_page!(attrs) do
+    case create_error_page(attrs) do
+      {:ok, error_page} -> error_page
+      {:error, changeset} -> raise "failed to create error page, got: #{inspect(changeset.errors)}"
+    end
+  end
+
+  @doc """
+  Returns attr data to load the default error_pages into new sites.
+  """
+  @spec default_error_pages() :: [map()]
+  @doc type: :error_pages
+  def default_error_pages do
+    for status <- [404, 500] do
+      %{
+        status: status,
+        template: Plug.Conn.Status.reason_phrase(status)
+      }
+    end
+  end
+
+  @doc """
+  Updates an error page.
+  """
+  @doc type: :error_pages
+  @spec update_error_page(ErrorPage.t(), map()) :: {:ok, ErrorPage.t()} | {:error, Changeset.t()}
+  def update_error_page(error_page, attrs) do
+    error_page
+    |> ErrorPage.changeset(attrs)
+    |> Repo.update()
+    |> tap(&maybe_reload_error_page/1)
+  end
+
+  def maybe_reload_error_page({:ok, error_page}), do: PubSub.error_page_updated(error_page)
+  def maybe_reload_error_page({:error, _error_page}), do: :noop
+
+  @doc """
+  Deletes an error page.
+  """
+  @doc type: :error_pages
+  @spec delete_error_page(ErrorPage.t()) :: {:ok, ErrorPage.t()} | {:error, Changeset.t()}
+  def delete_error_page(error_page) do
+    Repo.delete(error_page)
+  end
+
   # PAGE EVENT HANDLERS
 
   @doc """

lib/beacon/content/error_page.ex

@@ -0,0 +1,68 @@
+defmodule Beacon.Content.ErrorPage do
+  @moduledoc """
+  Stores a template which can be rendered for error responses.
+
+  An ErrorPage contains four main fields:
+
+    * `:status` - the status code for which this ErrorPage is to be used
+    * `:template` - the template to be rendered
+    * `:site` - the Beacon site which should use this page
+    * `:layout_id` - the ID of the Beacon Layout which is used for rendering
+
+  > #### Do not create or edit ErrorPages manually {: .warning}
+  >
+  > Use the public functions in `Beacon.Content` instead.
+  > The functions in that module guarantee that all dependencies
+  > are created correctly and all processes are updated.
+  > Manipulating data manually will most likely result
+  > in inconsistent behavior and crashes.
+
+  """
+  use Beacon.Schema
+
+  import Beacon.Utils, only: [list_to_typespec: 1]
+  import Ecto.Changeset
+
+  # We can use Range.to_list/1 here when we upgrade to Elixir 1.15
+  @valid_error_statuses Enum.to_list(400..418) ++
+                          Enum.to_list(421..426) ++
+                          [428, 429, 431, 451] ++
+                          Enum.to_list(500..508) ++
+                          [510, 511]
+
+  @type t :: %__MODULE__{
+          id: Ecto.UUID.t(),
+          site: Beacon.Types.Site.t(),
+          status: error_status(),
+          template: binary(),
+          layout_id: Ecto.UUID.t(),
+          layout: Beacon.Content.Layout.t(),
+          inserted_at: DateTime.t(),
+          updated_at: DateTime.t()
+        }
+
+  @type error_status :: unquote(list_to_typespec(@valid_error_statuses))
+
+  schema "beacon_error_pages" do
+    field :site, Beacon.Types.Site
+    field :status, :integer
+    field :template, :string
+
+    belongs_to :layout, Beacon.Content.Layout
+
+    timestamps()
+  end
+
+  @doc false
+  def changeset(%__MODULE__{} = error_page, attrs) do
+    fields = ~w(status template site layout_id)a
+
+    error_page
+    |> cast(attrs, fields)
+    |> validate_required(fields)
+    |> unique_constraint([:status, :site])
+    |> validate_inclusion(:status, @valid_error_statuses)
+  end
+
+  def valid_statuses, do: @valid_error_statuses
+end

lib/beacon/content/layout.ex

@@ -49,4 +49,7 @@ defmodule Beacon.Content.Layout do
     |> cast(attrs, [:site, :title, :template, :meta_tags, :resource_links])
     |> validate_required([:site, :title])
   end
+
+  @doc false
+  def fetch(layout, key), do: Map.fetch(layout, key)
 end