Allow queries without batch keys

lib/dataloader/ecto.ex

@@ -335,6 +335,10 @@ if Code.ensure_loaded?(Ecto) do
       end
     end
 
+    defp load_rows(nil, _inputs, _queryable, query, repo, repo_opts) do
+      repo.all(query, repo_opts)
+    end
+
     defp load_rows(col, inputs, queryable, query, repo, repo_opts) do
       pk = queryable.__schema__(:primary_key)
 
@@ -572,6 +576,10 @@ if Code.ensure_loaded?(Ecto) do
           """
       end
 
+      defp normalize_value(_queryable, []) do
+        {:not_primary, nil, nil}
+      end
+
       defp normalize_value(queryable, [{col, value}]) do
         case queryable.__schema__(:primary_key) do
           [^col] ->

test/dataloader/ecto/limit_query_test.exs

@@ -78,6 +78,35 @@ defmodule Dataloader.LimitQueryTest do
     assert [post3] == Dataloader.get(loader, Test, args, user_id: user2.id)
   end
 
+  test "Query limit without filters", %{loader: loader} do
+    user1 = %User{username: "Ben Wilson"} |> Repo.insert!()
+    user2 = %User{username: "Bruce Williams"} |> Repo.insert!()
+
+    [post1, post2, _post3, _post4] =
+      [
+        %Post{user_id: user1.id, title: "foo"},
+        %Post{user_id: user1.id, title: "baz"},
+        %Post{user_id: user2.id, title: "bar"},
+        %Post{user_id: user2.id, title: "qux"}
+      ]
+      |> Enum.map(&Repo.insert!/1)
+
+    args0 = {{:one, Post}, %{limit: 1, order_by: [asc: :id]}}
+    args1 = {{:many, Post}, %{limit: 1, order_by: [asc: :id]}}
+    args2 = {{:many, Post}, %{limit: 2, order_by: [asc: :id]}}
+
+    loader =
+      loader
+      |> Dataloader.load(Test, args0, [])
+      |> Dataloader.load(Test, args1, [])
+      |> Dataloader.load(Test, args2, [])
+      |> Dataloader.run()
+
+    assert post1 == Dataloader.get(loader, Test, args0, [])
+    assert [post1] == Dataloader.get(loader, Test, args1, [])
+    assert [post1, post2] == Dataloader.get(loader, Test, args2, [])
+  end
+
   test "Load has-many association with limit", %{loader: loader} do
     user1 = %User{username: "Ben Wilson"} |> Repo.insert!()
     user2 = %User{username: "Bruce Williams"} |> Repo.insert!()

test/dataloader/ecto_test.exs

@@ -308,6 +308,26 @@ defmodule Dataloader.EctoTest do
     assert message =~ "Cardinality"
   end
 
+  test "basic loading of all things", %{loader: loader} do
+    user1 = %User{username: "Ben Wilson"} |> Repo.insert!()
+    user2 = %User{username: "Bruce Williams"} |> Repo.insert!()
+
+    [post1, post2, post3] =
+      [
+        %Post{user_id: user1.id, title: "foo"},
+        %Post{user_id: user1.id, title: "baz"},
+        %Post{user_id: user2.id, title: "bar"}
+      ]
+      |> Enum.map(&Repo.insert!/1)
+
+    loader =
+      loader
+      |> Dataloader.load(Test, {:many, Post}, [])
+      |> Dataloader.run()
+
+    assert [post1, post2, post3] == Dataloader.get(loader, Test, {:many, Post}, [])
+  end
+
   describe "many_to_many" do
     test "basic loading works", %{loader: loader} do
       user1 = %User{username: "Ben Wilson"} |> Repo.insert!()