WIP

lib/ash_postgres.ex

@@ -1,18 +1,34 @@
 defmodule AshPostgres do
+  @using_opts_schema Ashton.schema(
+                       opts: [
+                         repo: :atom
+                       ],
+                       required: [:repo],
+                       describe: [
+                         repo:
+                           "The repo that will be used to fetch your data. See the `Ecto.Repo` documentation for more"
+                       ],
+                       constraints: [
+                         repo:
+                           {&AshPostgres.postgres_repo?/1, "must be using the postgres adapter"}
+                       ]
+                     )
+
+  @moduledoc """
+  A postgres data layer that levereges Ecto's postgres tools.
+
+  To use it, add `use AshPostgres, repo: MyRepo` to your resource, after `use Ash.Resource`
+
+  #{Ashton.document(@using_opts_schema)}
+  """
   @behaviour Ash.DataLayer
 
   defmacro __using__(opts) do
-    quote bind_quoted: [repo: opts[:repo]] do
+    quote bind_quoted: [opts: opts] do
+      opts = AshPostgres.validate_using_opts(__MODULE__, opts)
+
       @data_layer AshPostgres
-      @repo repo
-
-      unless repo do
-        raise "You must pass the `repo` option to `use AshPostgres` for #{__MODULE__}"
-      end
-
-      unless repo.__adapter__() == Ecto.Adapters.Postgres do
-        raise "Only Ecto.Adapters.Postgres is supported with AshPostgres for now"
-      end
+      @repo opts[:repo]
 
       def repo() do
         @repo
@@ -20,6 +36,24 @@ defmodule AshPostgres do
     end
   end
 
+  def validate_using_opts(mod, opts) do
+    case Ashton.validate(opts, @using_opts_schema) do
+      {:ok, opts} ->
+        opts
+
+      {:error, [{key, message} | _]} ->
+        raise Ash.Error.ResourceDslError,
+          resource: mod,
+          using: __MODULE__,
+          option: key,
+          message: message
+    end
+  end
+
+  def postgres_repo?(repo) do
+    repo.__adapter__() == Ecto.Adapters.Postgres
+  end
+
   def repo(resource) do
     resource.repo()
   end

mix.lock

@@ -1,5 +1,6 @@
 %{
   "ash": {:hex, :ash, "0.1.0", "84b0e47f0f52e34bae71b682bb0689dc429b3da28ad3c02929226199a1941680", [:mix], [{:ecto, "~> 3.0", [hex: :ecto, repo: "hexpm", optional: false]}, {:ets, "~> 0.7.3", [hex: :ets, repo: "hexpm", optional: false]}], "hexpm"},
+  "ashton": {:hex, :ashton, "0.3.9", "1c089d62d35a17c1f31db4e9130fb90f8d802c8c9078fd29138be7b6b93305b5", [:mix], [], "hexpm"},
   "connection": {:hex, :connection, "1.0.4", "a1cae72211f0eef17705aaededacac3eb30e6625b04a6117c1b2db6ace7d5976", [:mix], [], "hexpm"},
   "dataloader": {:hex, :dataloader, "1.0.6", "fb724d6d3fb6acb87d27e3b32dea3a307936ad2d245faf9cf5221d1323d6a4ba", [:mix], [{:ecto, ">= 0.0.0", [hex: :ecto, repo: "hexpm", optional: true]}], "hexpm"},
   "db_connection": {:hex, :db_connection, "2.1.1", "a51e8a2ee54ef2ae6ec41a668c85787ed40cb8944928c191280fe34c15b76ae5", [:mix], [{:connection, "~> 1.0.2", [hex: :connection, repo: "hexpm", optional: false]}], "hexpm"},