reject registration if user already exists

lib/chiya/accounts.ex

@@ -8,6 +8,10 @@ defmodule Chiya.Accounts do
 
   alias Chiya.Accounts.{User, UserToken, UserNotifier}
 
+  def has_user?() do
+    Repo.exists?(User)
+  end
+
   ## Database getters
 
   @doc """

lib/chiya_web/live/user_registration_live.ex

@@ -31,6 +31,10 @@ defmodule ChiyaWeb.UserRegistrationLive do
           Oops, something went wrong! Please check the errors below.
         </.error>
 
+        <.error :if={@already_registered}>
+          Oops, you cannot register. The bouncer has denied you entry!
+        </.error>
+
         <.input field={@form[:email]} type="email" label="Email" required />
         <.input field={@form[:password]} type="password" label="Password" required />
 
@@ -47,26 +51,30 @@ defmodule ChiyaWeb.UserRegistrationLive do
 
     socket =
       socket
-      |> assign(trigger_submit: false, check_errors: false)
+      |> assign(trigger_submit: false, check_errors: false, already_registered: false)
       |> assign_form(changeset)
 
     {:ok, socket, temporary_assigns: [form: nil]}
   end
 
   def handle_event("save", %{"user" => user_params}, socket) do
-    case Accounts.register_user(user_params) do
-      {:ok, user} ->
-        {:ok, _} =
-          Accounts.deliver_user_confirmation_instructions(
-            user,
-            &url(~p"/users/confirm/#{&1}")
-          )
+    if Accounts.has_user?() do
+      {:noreply, socket |> assign(already_registered: true)}
+    else
+      case Accounts.register_user(user_params) do
+        {:ok, user} ->
+          {:ok, _} =
+            Accounts.deliver_user_confirmation_instructions(
+              user,
+              &url(~p"/users/confirm/#{&1}")
+            )
 
-        changeset = Accounts.change_user_registration(user)
-        {:noreply, socket |> assign(trigger_submit: true) |> assign_form(changeset)}
+          changeset = Accounts.change_user_registration(user)
+          {:noreply, socket |> assign(trigger_submit: true) |> assign_form(changeset)}
 
-      {:error, %Ecto.Changeset{} = changeset} ->
-        {:noreply, socket |> assign(check_errors: true) |> assign_form(changeset)}
+        {:error, %Ecto.Changeset{} = changeset} ->
+          {:noreply, socket |> assign(check_errors: true) |> assign_form(changeset)}
+      end
     end
   end
 

test/chiya_web/live/user_registration_live_test.exs

@@ -54,20 +54,22 @@ defmodule ChiyaWeb.UserRegistrationLiveTest do
       assert response =~ "Settings"
       assert response =~ "Log out"
     end
+  end
 
-    test "renders errors for duplicated email", %{conn: conn} do
+  describe "register another user" do
+    test "renders errors if another user already exists", %{conn: conn} do
       {:ok, lv, _html} = live(conn, ~p"/users/register")
 
-      user = user_fixture(%{email: "test@email.com"})
+      _user = user_fixture(%{email: "test@email.com"})
 
       result =
         lv
         |> form("#registration_form",
-          user: %{"email" => user.email, "password" => "valid_password"}
+          user: %{"email" => "attacker@email.com", "password" => "valid_password"}
         )
         |> render_submit()
 
-      assert result =~ "has already been taken"
+      assert result =~ "you cannot register"
     end
   end