Merge pull request #126 from jueberschlag/fix/ecto-high-number-of-bat…

…ches

Fix/Ecto high number of batches

lib/dataloader/ecto.ex

@@ -600,8 +600,10 @@ if Code.ensure_loaded?(Ecto) do
           on_timeout: :kill_task
         ]
 
+        batches = Enum.to_list(source.batches)
+
         results =
-          source.batches
+          batches
           |> Task.async_stream(
             fn batch ->
               id = :erlang.unique_integer()
@@ -621,7 +623,7 @@ if Code.ensure_loaded?(Ecto) do
             {:exit, reason} -> {:error, reason}
           end)
 
-        source.batches
+        batches
         |> Enum.map(fn {key, _set} -> key end)
         |> Enum.zip(results)
         |> Map.new()

test/dataloader/ecto_test.exs

@@ -456,4 +456,34 @@ defmodule Dataloader.EctoTest do
       Dataloader.get(loader, Timeout, User, user.id)
     end
   end
+
+  test "when there are many batches (more than 32)" do
+    source =
+      Dataloader.Ecto.new(
+        Repo,
+        query: fn queryable, _ ->
+          queryable
+        end
+      )
+
+    loader =
+      Dataloader.new()
+      |> Dataloader.add_source(Test, source)
+
+    users =
+      for x <- 0..50 do
+        %User{username: "Ben Wilson #{x}"} |> Repo.insert!()
+      end
+
+    loader =
+      users
+      |> Enum.reduce(loader, fn user, loader ->
+        # Force a batch per user by adding id to batch key
+        Dataloader.load(loader, Test, {User, id: user.id}, user.id)
+      end)
+      |> Dataloader.run()
+
+    assert Enum.map(users, &Dataloader.get(loader, Test, {User, id: &1.id}, &1.id)) ==
+             users
+  end
 end