correctly return error on gallery unique constraint

lib/philomena/galleries.ex

@@ -169,6 +169,17 @@ defmodule Philomena.Galleries do
       {:ok, count}
     end)
     |> Repo.transaction()
+    |> case do
+      {:ok, result} ->
+        Images.reindex_image(image)
+        notify_gallery(gallery)
+        reindex_gallery(gallery)
+
+        {:ok, result}
+
+      error ->
+        error
+    end
   end
 
   def remove_image_from_gallery(gallery, image) do
@@ -201,6 +212,16 @@ defmodule Philomena.Galleries do
       {:ok, count}
     end)
     |> Repo.transaction()
+    |> case do
+      {:ok, result} ->
+        Images.reindex_image(image)
+        reindex_gallery(gallery)
+
+        {:ok, result}
+
+      error ->
+        error
+    end
   end
 
   defp last_position(gallery_id) do

lib/philomena/galleries/interaction.ex

@@ -19,6 +19,7 @@ defmodule Philomena.Galleries.Interaction do
     |> cast(attrs, [:image_id, :position])
     |> validate_required([:image_id, :position])
     |> foreign_key_constraint(:image_id, name: :fk_rails_bb5ebe2a77)
+    |> unique_constraint(:image_id, name: :index_gallery_interactions_on_gallery_id_and_image_id)
     |> case do
       %{valid?: false, changes: changes} = changeset when changes == %{} ->
         %{changeset | action: :ignore}

lib/philomena_web/controllers/gallery/image_controller.ex

@@ -1,10 +1,9 @@
 defmodule PhilomenaWeb.Gallery.ImageController do
   use PhilomenaWeb, :controller
 
-  alias Philomena.Images.Image
   alias Philomena.Galleries.Gallery
-  alias Philomena.Images
   alias Philomena.Galleries
+  alias Philomena.Images.Image
 
   plug PhilomenaWeb.FilterBannedUsersPlug
 
@@ -15,25 +14,26 @@ defmodule PhilomenaWeb.Gallery.ImageController do
   plug :load_and_authorize_resource, model: Image, id_name: "image_id", persisted: true
 
   def create(conn, _params) do
-    gallery = conn.assigns.gallery
-    image = conn.assigns.image
+    case Galleries.add_image_to_gallery(conn.assigns.gallery, conn.assigns.image) do
+      {:ok, _gallery} ->
+        json(conn, %{})
 
-    {:ok, _gallery} = Galleries.add_image_to_gallery(gallery, image)
-    Galleries.notify_gallery(gallery)
-    Galleries.reindex_gallery(gallery)
-    Images.reindex_image(image)
-
-    json(conn, %{})
+      _error ->
+        conn
+        |> put_status(:bad_request)
+        |> json(%{})
+    end
   end
 
   def delete(conn, _params) do
-    gallery = conn.assigns.gallery
-    image = conn.assigns.image
+    case Galleries.remove_image_from_gallery(conn.assigns.gallery, conn.assigns.image) do
+      {:ok, _gallery} ->
+        json(conn, %{})
 
-    {:ok, _gallery} = Galleries.remove_image_from_gallery(gallery, image)
-    Galleries.reindex_gallery(gallery)
-    Images.reindex_image(image)
-
-    json(conn, %{})
+      _error ->
+        conn
+        |> put_status(:bad_request)
+        |> json(%{})
+    end
   end
 end