Part 4: Update create action

lib/catcasts_web/controllers/session_controller.ex

@@ -2,7 +2,7 @@ defmodule CatcastsWeb.SessionController do
   use CatcastsWeb, :controller
   plug(Ueberauth)
 
-  alias Catcasts.User
+  alias Catcasts.{Repo, User}
 
   def create(%{assigns: %{ueberauth_auth: auth}} = conn, _params) do
     user_params = %{
@@ -14,5 +14,28 @@ defmodule CatcastsWeb.SessionController do
     }
 
     changeset = User.changeset(%User{}, user_params)
+
+    case insert_or_update_user(changeset) do
+      {:ok, user} ->
+        conn
+        |> put_flash(:info, "Thank you for signing in!")
+        |> put_session(:user_id, user.id)
+        |> redirect(to: Routes.page_path(conn, :index))
+
+      {:error, _reason} ->
+        conn
+        |> put_flash(:error, "Error signing in")
+        |> redirect(to: Routes.page_path(conn, :index))
+    end
+  end
+
+  defp insert_or_update_user(changeset) do
+    case Repo.get_by(User, email: changeset.changes.email) do
+      nil ->
+        Repo.insert(changeset)
+
+      user ->
+        {:ok, user}
+    end
   end
 end