Allow app web helpers in Backpex extensions

guides/actions/item-actions.md

@@ -38,6 +38,8 @@ In the above example, we only return the `show` item action. This way we replace
 
 An item action is a module that uses the `Backpex.ItemAction` module. To get started, you can use the `BackpexWeb` module and provide the `:item_action` option. This will import the necessary functions and macros to define an item action.
 
+If the item action needs your application's Gettext backend, components, or verified routes, you can additionally `use MyAppWeb, :html`. Both `use` orders are supported.
+
 In the following example, we define an item action to navigate to the show view of a user.
 
 ```elixir

guides/fields/custom-fields.md

@@ -53,6 +53,18 @@ The `render_form/1` function returns markup that is used to render a form on `ed
 
 See `Backpex.Field` for more information on the available callback functions. For example, you can implement `render_index_form/1` to make the field editable in the index view.
 
+## Using your application's web helpers
+
+Custom fields are LiveComponents. If a field needs helpers from your application, such as Gettext, core components, or verified routes, configure your application's LiveComponent entrypoint:
+
+```elixir
+use Backpex.Field,
+  config_schema: @config_schema,
+  live_component: {MyAppWeb, :live_component}
+```
+
+The standard Phoenix-generated `MyAppWeb, :live_component` entrypoint includes the application's HTML helpers while setting up `Phoenix.LiveComponent` exactly once. Do not additionally `use MyAppWeb, :html` in the same field module.
+
 ## Add field option validation
 
 With Backpex v0.9 we are validating field options. This ensures that only field options that are actually used by the field can be defined in the field options map. So if your custom field requires certain field options, make sure you define them.

guides/filter/custom-filter.md

@@ -6,6 +6,8 @@ Backpex ships with a set of default filters that can be used to filter the data.
 
 You can create a custom filter by using the `filter` macro from the `BackpexWeb` module. It automatically implements the `Backpex.Filter` behavior and defines some aliases and imports.
 
+If the filter needs your application's Gettext backend, components, or verified routes, you can additionally `use MyAppWeb, :html`. This also works with the built-in filter macros such as `use Backpex.Filters.Select`, and both `use` orders are supported.
+
 ### Required Callbacks
 
 When creating a custom filter, you need to implement the following callbacks:

guides/upgrading/v0.19.md

@@ -63,3 +63,47 @@ defmodule MyAppWeb.PostLive do
   end
 end
 ```
+
+## Backpex extension modules now import `Phoenix.Component`
+
+The `BackpexWeb` entrypoints for item actions, filters, and metrics now import
+`Phoenix.Component` instead of using it. This avoids registering the
+declarative `@before_compile` hook twice when an extension also uses its application's
+HTML entrypoint.
+
+You can now use application-level Gettext, components, and verified routes directly in
+these extensions, in either order:
+
+```elixir
+defmodule MyAppWeb.ItemActions.Archive do
+  use BackpexWeb, :item_action
+  use MyAppWeb, :html
+
+  # ...
+end
+```
+
+This also applies to custom filters using `BackpexWeb, :filter` or one of
+`Backpex.Filters.Select`, `Backpex.Filters.MultiSelect`, `Backpex.Filters.Boolean`, and
+`Backpex.Filters.Range`, as well as metrics using `BackpexWeb, :metric`.
+
+No change is required for extensions that only use `~H` and the helpers provided by
+Backpex. If an item action, filter, or metric declares its own function components with
+`attr` or `slot`, it must now additionally `use MyAppWeb, :html` or
+`use Phoenix.Component`.
+
+## Custom fields can use the host LiveComponent entrypoint
+
+`Backpex.Field` still needs the complete `Phoenix.LiveComponent` setup. To make your
+application's Gettext backend, components, and verified routes available without using
+`Phoenix.Component` twice, configure the host LiveComponent entrypoint:
+
+```elixir
+use Backpex.Field,
+  config_schema: @config_schema,
+  live_component: {MyAppWeb, :live_component}
+```
+
+The configured entrypoint must set up a `Phoenix.LiveComponent`, as the standard
+Phoenix-generated `MyAppWeb, :live_component` entrypoint does. It replaces Backpex's
+default LiveComponent setup, so do not additionally `use MyAppWeb, :html` in the field.

lib/backpex/field.ex

@@ -226,15 +226,35 @@ defmodule Backpex.Field do
 
   @doc """
   Defines `Backpex.Field` behaviour and provides default implementations.
+
+  A custom field can use its application's LiveComponent entrypoint to make
+  application helpers such as Gettext and verified routes available:
+
+      use Backpex.Field,
+        config_schema: @config_schema,
+        live_component: {MyAppWeb, :live_component}
+
+  The configured entrypoint must set up a `Phoenix.LiveComponent`, as the standard
+  Phoenix-generated `MyAppWeb, :live_component` entrypoint does.
   """
   defmacro __using__(opts) do
-    quote bind_quoted: [opts: opts] do
+    opts = Macro.expand(opts, __CALLER__)
+
+    if !Keyword.keyword?(opts) do
+      raise ArgumentError, "expected Backpex.Field options to be a keyword list, got: #{Macro.to_string(opts)}"
+    end
+
+    {live_component, opts} = Keyword.pop(opts, :live_component)
+    live_component = live_component(live_component, __CALLER__)
+
+    quote bind_quoted: [opts: opts], unquote: true do
       @config_schema opts[:config_schema] || []
 
       @before_compile Backpex.Field
       @behaviour Backpex.Field
 
-      use BackpexWeb, :field
+      unquote(live_component)
+      use BackpexWeb, :field_helpers
 
       @doc """
       Returns the schema of configurable options for this field.
@@ -262,6 +282,30 @@ defmodule Backpex.Field do
     end
   end
 
+  defp live_component(nil, _caller) do
+    quote do
+      use Phoenix.LiveComponent
+    end
+  end
+
+  defp live_component({module, entrypoint}, caller) when is_atom(entrypoint) do
+    module = Macro.expand(module, caller)
+
+    if !is_atom(module) do
+      raise ArgumentError,
+            "expected :live_component to contain a module, got: #{Macro.to_string(module)}"
+    end
+
+    quote do
+      use unquote(module), unquote(entrypoint)
+    end
+  end
+
+  defp live_component(live_component, _caller) do
+    raise ArgumentError,
+          "expected :live_component to be a {module, entrypoint} tuple, got: #{Macro.to_string(live_component)}"
+  end
+
   defmacro __before_compile__(_env) do
     quote generated: true do
       import Ecto.Query

lib/backpex/filters/boolean.ex

@@ -40,6 +40,7 @@ defmodule Backpex.Filters.Boolean do
   > In addition it will add a `render` and `render_form` function in order to display the corresponding filter.
   > It will also implement the `Backpex.Filter.query` function to define a boolean query.
   """
+  use Phoenix.Component
   use BackpexWeb, :filter
 
   @doc """

lib/backpex/filters/multi_select.ex

@@ -24,6 +24,7 @@ defmodule Backpex.Filters.MultiSelect do
   >
   > When you `use Backpex.Filters.MultiSelect`, the `Backpex.Filters.MultiSelect` module will set `@behavior Backpex.Filters.Select`. In addition it will add a `render` and `render_form` function in order to display the corresponding filter.
   """
+  use Phoenix.Component
   use BackpexWeb, :filter
 
   import Backpex.HTML.CoreComponents

lib/backpex/filters/range.ex

@@ -24,6 +24,7 @@ defmodule Backpex.Filters.Range do
   > In addition it will add a `render` and `render_form` function in order to display the corresponding filter.
   > It will also implement the `Backpex.Filter.query` function to define a range query.
   """
+  use Phoenix.Component
   use BackpexWeb, :filter
 
   require Backpex

lib/backpex/filters/select.ex

@@ -30,6 +30,7 @@ defmodule Backpex.Filters.Select do
   > When you `use Backpex.Filters.Select`, the `Backpex.Filters.Select` module will set `@behavior Backpex.Filters.Select`.
   > In addition it will add a `render` and `render_form` function in order to display the corresponding filter.
   """
+  use Phoenix.Component
   use BackpexWeb, :filter
 
   @doc """

lib/backpex/metrics/value.ex

@@ -32,6 +32,7 @@ defmodule Backpex.Metrics.Value do
       end
   """
 
+  use Phoenix.Component
   use BackpexWeb, :metric
 
   attr :metric, :any, required: true, doc: "the metric to be rendered"

lib/backpex_web.ex

@@ -19,6 +19,24 @@ defmodule BackpexWeb do
     end
   end
 
+  @doc """
+  Includes the functions and helpers needed to render HEEx without setting up a
+  `Phoenix.Component` module.
+
+  This entrypoint is intended for Backpex extension modules that may additionally
+  `use MyAppWeb, :html`. Importing `Phoenix.Component` provides the `~H` sigil and
+  component helpers without registering another declarative `@before_compile` hook.
+  """
+  def heex do
+    quote do
+      import Phoenix.Component
+
+      require Phoenix.Component.Declarative
+
+      unquote(html_helpers())
+    end
+  end
+
   @doc """
   Includes the functions and helpers available inside a `Backpex.LiveResource`.
 
@@ -40,13 +58,7 @@ defmodule BackpexWeb do
   # the module additionally brings in the component-aware `def` (via `use MyAppWeb, :html`),
   # regardless of the order of the `use` statements.
   def live_resource do
-    quote do
-      import Phoenix.Component
-
-      require Phoenix.Component.Declarative
-
-      unquote(html_helpers())
-    end
+    heex()
   end
 
   @doc """
@@ -56,6 +68,13 @@ defmodule BackpexWeb do
     quote do
       use Phoenix.LiveComponent
 
+      unquote(field_helpers())
+    end
+  end
+
+  @doc false
+  def field_helpers do
+    quote do
       alias Backpex.HTML
       alias Backpex.HTML.Form, as: BackpexForm
       alias Backpex.HTML.Layout
@@ -71,35 +90,32 @@ defmodule BackpexWeb do
   """
   def item_action do
     quote do
-      use Phoenix.Component
       use Backpex.ItemAction
 
       import Phoenix.LiveView
 
       alias Backpex.Router
 
-      unquote(html_helpers())
+      unquote(heex())
     end
   end
 
   def filter do
     quote do
-      use Phoenix.Component
-
       import Backpex.HTML.Form, only: [error: 1]
       import Ecto.Query, warn: false
 
-      unquote(html_helpers())
+      unquote(heex())
     end
   end
 
   def metric do
     quote do
       @behaviour Backpex.Metric
 
-      use Phoenix.Component
-
       import Ecto.Query
+
+      unquote(heex())
     end
   end
 

test/backpex/web_helpers_test.exs

@@ -0,0 +1,39 @@
+defmodule Backpex.WebHelpersTest do
+  use ExUnit.Case, async: false
+
+  @fixture Path.expand("../fixtures/web_helpers/extension_modules.fixture", __DIR__)
+
+  @fixture_modules [
+    Backpex.WebHelpersTest.Helpers,
+    Backpex.WebHelpersTest.Web,
+    Backpex.WebHelpersTest.ItemActionBackpexFirst,
+    Backpex.WebHelpersTest.ItemActionWebFirst,
+    Backpex.WebHelpersTest.FilterBackpexFirst,
+    Backpex.WebHelpersTest.FilterWebFirst,
+    Backpex.WebHelpersTest.SelectFilterBackpexFirst,
+    Backpex.WebHelpersTest.SelectFilterWebFirst,
+    Backpex.WebHelpersTest.MetricBackpexFirst,
+    Backpex.WebHelpersTest.MetricWebFirst,
+    Backpex.WebHelpersTest.Field
+  ]
+
+  test "Backpex extensions compile with host web helpers without warnings" do
+    purge_fixture_modules()
+    on_exit(&purge_fixture_modules/0)
+
+    assert {:ok, modules, %{compile_warnings: [], runtime_warnings: []}} =
+             Kernel.ParallelCompiler.compile([@fixture],
+               max_concurrency: 1,
+               return_diagnostics: true
+             )
+
+    assert Enum.sort(modules) == Enum.sort(@fixture_modules)
+  end
+
+  defp purge_fixture_modules do
+    Enum.each(@fixture_modules, fn module ->
+      :code.purge(module)
+      :code.delete(module)
+    end)
+  end
+end