Better way of setting defaults

lib/chess/store/game.ex

@@ -11,8 +11,8 @@ defmodule Chess.Store.Game do
   alias Chess.Store.Game
 
   schema "games" do
-    field :board, :map
-    field :turn, :string
+    field :board, :map, default: Board.default()
+    field :turn, :string, default: "white"
 
     belongs_to :user, Chess.Auth.User
     belongs_to :opponent, Chess.Auth.User, references: :id
@@ -20,16 +20,6 @@ defmodule Chess.Store.Game do
     timestamps()
   end
 
-  def create_changeset(struct, params \\ %{}) do
-    struct
-    |> cast(params, required_attrs())
-    |> foreign_key_constraint(:user_id)
-    |> foreign_key_constraint(:opponent_id)
-    |> put_change(:board, Board.default())
-    |> put_change(:turn, default_turn())
-    |> validate_required(required_attrs())
-  end
-
   def changeset(struct, params \\ %{}) do
     struct
     |> cast(params, required_attrs())
@@ -53,8 +43,4 @@ defmodule Chess.Store.Game do
   end
 
   defp required_attrs, do: ~w[board turn user_id opponent_id]a
-
-  defp default_turn do
-    "white"
-  end
 end

lib/chess_web/controllers/game_controller.ex

@@ -31,7 +31,7 @@ defmodule ChessWeb.GameController do
   end
 
   def create(conn, %{"game" => %{"opponent_id" => opponent_id}}) do
-    changeset = Game.create_changeset(
+    changeset = Game.changeset(
       %Game{},
       %{
         user_id: current_user(conn).id,

test/chess/store/game_test.exs

@@ -40,7 +40,7 @@ defmodule Chess.GameTest do
       user = create_user("link", "ilovezelda")
       opponent = create_user("zelda", "ganonsucks")
 
-      attrs = %{user_id: user.id, opponent_id: opponent.id}
+      attrs = %{board: nil, user_id: user.id, opponent_id: opponent.id}
       changeset = Game.changeset(%Game{}, attrs)
 
       refute changeset.valid?

test/support/factory.ex

@@ -12,7 +12,7 @@ defmodule Chess.Factory do
   end
 
   def create_game_for(user, opponent) do
-    Game.create_changeset(
+    Game.changeset(
       %Game{},
       %{user_id: user.id, opponent_id: opponent.id}
     )