Merge pull request #174 from antonsatin/fix-custom-distinct

Fix for custom `distinct` handling in laterals

Author: benwilson512

lib/dataloader/ecto.ex

@@ -925,7 +925,8 @@ if Code.ensure_loaded?(Ecto) do
         build_preload_lateral_query(rest, join_query, :join_last)
       end
 
-      defp maybe_distinct(%Ecto.Query{distinct: dist} = query, _) when dist, do: query
+      defp maybe_distinct(%Ecto.Query{distinct: distinct} = query, _) when not is_nil(distinct),
+        do: query
 
       defp maybe_distinct(query, [%Ecto.Association.Has{}, %Ecto.Association.BelongsTo{} | _]),
         do: distinct(query, true)

test/dataloader/ecto/limit_query_test.exs

@@ -36,21 +36,21 @@ defmodule Dataloader.LimitQueryTest do
     |> preload(likes: :user)
   end
 
-  defp query(schema, %{limit: limit, order_by: order_by}, test_pid) do
+  defp query(schema, %{limit: limit, distinct: true, order_by: order_by}, test_pid) do
     send(test_pid, :querying)
 
     schema
     |> order_by(^order_by)
     |> limit(^limit)
+    |> distinct(true)
   end
 
-  defp query(schema, %{limit: limit, distinct: true, order_by: order_by}, test_pid) do
+  defp query(schema, %{limit: limit, order_by: order_by}, test_pid) do
     send(test_pid, :querying)
 
     schema
     |> order_by(^order_by)
     |> limit(^limit)
-    |> distinct(true)
   end
 
   test "Query limit does not apply globally", %{loader: loader} do