feat: impl callback query/2

Author: joeljuca

lib/swiss_schema.ex

@@ -373,6 +373,21 @@ defmodule SwissSchema do
               opts :: Keyword.t()
             ) :: Ecto.Schema.t()
 
+  @doc """
+  Allow complex queries to be made over the data store.
+
+  `c:query/2` accepts a function to intercept the query and modify as needed.
+
+  ## Examples
+
+      iex> import Ecto.Query, only: [where: 2]
+      iex> User.query(fn query -> query |> where([u], u.name == "John Lennon") end)
+      {:ok, [%User{name: "John Lennon"}]}
+  """
+  @doc group: "SwissSchema API"
+  @callback query(hook :: (Ecto.Query.t() -> Ecto.Query.t()), opts :: Keyword.t()) ::
+              {:ok, list(map())}
+
   @doc """
   Returns a lazy enumerable that emits all entries from the data store.
 
@@ -443,6 +458,7 @@ defmodule SwissSchema do
       end
 
     quote do
+      import Ecto.Query, only: [from: 1, select: 3]
       @behaviour SwissSchema
 
       @_swiss_schema %{
@@ -611,6 +627,20 @@ defmodule SwissSchema do
         insert_or_update!.(changeset, opts)
       end
 
+      @impl SwissSchema
+      def query(hook, opts \\ [])
+          when is_function(hook, 1) do
+        repo = Keyword.get(opts, :repo, unquote(repo))
+        all = Function.capture(repo, :all, 1)
+
+        query =
+          from(s in __MODULE__)
+          |> select([s], s)
+          |> then(hook)
+
+        {:ok, all.(query)}
+      end
+
       @deprecated "Use Ecto.Repo's stream/2 instead"
       @impl SwissSchema
       def stream(opts \\ []) do

test/swiss_schema_test.exs

@@ -133,6 +133,10 @@ defmodule SwissSchemaTest do
       assert function_exported?(SwissSchemaTest.User, :get_by!, 2)
     end
 
+    test "define query/1" do
+      assert function_exported?(SwissSchemaTest.User, :query, 1)
+    end
+
     test "define stream/0" do
       assert function_exported?(SwissSchemaTest.User, :stream, 0)
     end
@@ -574,6 +578,22 @@ defmodule SwissSchemaTest do
     end
   end
 
+  describe "query/1" do
+    setup do: Enum.each(1..3, fn i -> user_mock(lucky_number: i) |> Repo.insert!() end)
+
+    test "accept a function to customize the query" do
+      assert {:ok, [%User{}, %User{}, %User{}]} = User.query(fn q -> q end)
+    end
+
+    test "accepts a custom Ecto repo thru :repo opt" do
+      1..3
+      |> Enum.map(fn _ -> user_mock() |> Map.drop([:__struct__, :__meta__, :id]) end)
+      |> then(&Repo2.insert_all(User, &1))
+
+      assert {:ok, [%User{}, %User{}, %User{}]} = User.query(fn q -> q end, repo: Repo2)
+    end
+  end
+
   describe "update_all/2" do
     setup do: Enum.each(1..5, fn i -> user_mock(lucky_number: i) |> Repo.insert!() end)