Add limit & filter to scores

lib/scoreboard/games/games.ex

@@ -6,15 +6,30 @@ defmodule Scoreboard.Games do
   import Ecto.Query, warn: false
   alias Scoreboard.Repo
 
-  alias Scoreboard.Games.Player
+  alias Scoreboard.Games.{Player, Score}
 
   def data() do
     Dataloader.Ecto.new(Scoreboard.Repo, query: &query/2)
   end
 
-  def query(queryable, _params) do
-    queryable
+  @doc """
+  Pattern match to build more specific queries
+  """
+  def query(Score, params) do
+    params
+    |> Map.put_new(:limit, 10)
+    |> Map.to_list()
+    |> Enum.reduce(Score, &apply_param/2)
   end
+  def query(queryable, _params), do: queryable
+
+  @doc """
+  reduce function
+  """
+  def apply_param({:limit, num}, queryable), do: queryable |> limit(^num)
+  def apply_param({:player_id, player_id}, queryable), do: queryable |> where([score], score.player_id == ^player_id)
+  def apply_param(_param, queryable), do: queryable
+
 
   def get(queryable, id) do
     case Repo.get(queryable, id) do

lib/scoreboard_web/schema.ex

@@ -19,7 +19,11 @@ defmodule ScoreboardWeb.Schema do
   object :game do
     field(:id, non_null(:id))
     field(:name, non_null(:string))
-    field(:scores, list_of(:score), resolve: dataloader(:games))
+    field :scores, list_of(:score) do
+      arg :limit, :integer
+      arg :player_id, :id
+      resolve dataloader(:games)
+    end
   end
 
   @desc "A Player"

test/scoreboard_web/schema_test.exs

@@ -63,6 +63,55 @@ defmodule Scoreboard.SchemaTest do
       assert get_in(data, ["game", "scores", first, "total"]) == score.total
       assert get_in(data, ["game", "scores", first, "player", "name"]) == context.player.name
     end
+
+    test("passing limit param to scores query", context) do
+      Repo.insert!(%Score{game_id: context.game.id, player_id: context.player.id, total: 101})
+
+      document = """
+      {
+        game(id: "#{context.game.id}") {
+          id
+          name
+          scores(limit: 0) {
+            total
+          }
+        }
+      }
+      """
+
+      result = Absinthe.run(document, ScoreboardWeb.Schema)
+
+      assert {:ok, %{data: data}} = result
+      assert length(get_in(data, ["game", "scores"])) == 0
+    end
+
+    test("passing limit & player_id param to scores query", context) do
+      sam = Repo.insert!(%Player{name: "Sam"})
+      Repo.insert!(%Score{game_id: context.game.id, player_id: context.player.id, total: 101})
+      Repo.insert!(%Score{game_id: context.game.id, player_id: sam.id, total: 12})
+
+      document = """
+      {
+        game(id: "#{context.game.id}") {
+          id
+          name
+          scores(limit: 5, player_id: "#{context.player.id}") {
+            total
+            player {
+              id
+            }
+          }
+        }
+      }
+      """
+
+      result = Absinthe.run(document, ScoreboardWeb.Schema)
+
+      assert {:ok, %{data: data}} = result
+      for %{"player" => %{"id" => id}} = _score <- get_in(data, ["game", "scores"]) do
+        assert id == context.player.id
+      end
+    end
   end
 
   describe("mutation queries") do