Avoid creating notifications for user performing the action

lib/philomena/comments.ex

@@ -72,14 +72,12 @@ defmodule Philomena.Comments do
   end
 
   def perform_notify(comment_id) do
-    comment = get_comment!(comment_id)
+    comment =
+      comment_id
+      |> get_comment!()
+      |> Repo.preload([:user, :image])
 
-    image =
-      comment
-      |> Repo.preload(:image)
-      |> Map.fetch!(:image)
-
-    Notifications.create_image_comment_notification(image, comment)
+    Notifications.create_image_comment_notification(comment.user, comment.image, comment)
   end
 
   @doc """

lib/philomena/notifications.ex

@@ -78,7 +78,7 @@ defmodule Philomena.Notifications do
 
   """
   def create_channel_live_notification(channel) do
-    Creator.create_single(ChannelSubscription, ChannelLiveNotification, :channel_id, channel)
+    Creator.create_single(ChannelSubscription, ChannelLiveNotification, nil, :channel_id, channel)
   end
 
   @doc """
@@ -86,14 +86,15 @@ defmodule Philomena.Notifications do
 
   ## Examples
 
-      iex> create_forum_post_notification(topic, post)
+      iex> create_forum_post_notification(user, topic, post)
       {:ok, 2}
 
   """
-  def create_forum_post_notification(topic, post) do
+  def create_forum_post_notification(user, topic, post) do
     Creator.create_double(
       TopicSubscription,
       ForumPostNotification,
+      user,
       :topic_id,
       topic,
       :post_id,
@@ -106,12 +107,12 @@ defmodule Philomena.Notifications do
 
   ## Examples
 
-      iex> create_forum_topic_notification(topic)
+      iex> create_forum_topic_notification(user, topic)
       {:ok, 2}
 
   """
-  def create_forum_topic_notification(topic) do
-    Creator.create_single(ForumSubscription, ForumTopicNotification, :topic_id, topic)
+  def create_forum_topic_notification(user, topic) do
+    Creator.create_single(ForumSubscription, ForumTopicNotification, user, :topic_id, topic)
   end
 
   @doc """
@@ -124,7 +125,13 @@ defmodule Philomena.Notifications do
 
   """
   def create_gallery_image_notification(gallery) do
-    Creator.create_single(GallerySubscription, GalleryImageNotification, :gallery_id, gallery)
+    Creator.create_single(
+      GallerySubscription,
+      GalleryImageNotification,
+      nil,
+      :gallery_id,
+      gallery
+    )
   end
 
   @doc """
@@ -132,14 +139,15 @@ defmodule Philomena.Notifications do
 
   ## Examples
 
-      iex> create_image_comment_notification(image, comment)
+      iex> create_image_comment_notification(user, image, comment)
       {:ok, 2}
 
   """
-  def create_image_comment_notification(image, comment) do
+  def create_image_comment_notification(user, image, comment) do
     Creator.create_double(
       ImageSubscription,
       ImageCommentNotification,
+      user,
       :image_id,
       image,
       :comment_id,
@@ -160,6 +168,7 @@ defmodule Philomena.Notifications do
     Creator.create_double(
       ImageSubscription,
       ImageMergeNotification,
+      nil,
       :target_id,
       target,
       :source_id,

lib/philomena/notifications/creator.ex

@@ -22,13 +22,13 @@ defmodule Philomena.Notifications.Creator do
 
   ## Example
 
-      iex> create_single(GallerySubscription, GalleryImageNotification, :gallery_id, gallery)
+      iex> create_single(GallerySubscription, GalleryImageNotification, nil, :gallery_id, gallery)
       {:ok, 2}
 
   """
-  def create_single(subscription, notification, name, object) do
+  def create_single(subscription, notification, user, name, object) do
     subscription
-    |> create_notification_query(name, object)
+    |> create_notification_query(user, name, object)
     |> create_notification(notification, name)
   end
 
@@ -45,6 +45,7 @@ defmodule Philomena.Notifications.Creator do
       iex> create_double(
       ...>   ImageSubscription,
       ...>   ImageCommentNotification,
+      ...>   user,
       ...>   :image_id,
       ...>   image,
       ...>   :comment_id,
@@ -53,9 +54,9 @@ defmodule Philomena.Notifications.Creator do
       {:ok, 2}
 
   """
-  def create_double(subscription, notification, name1, object1, name2, object2) do
+  def create_double(subscription, notification, user, name1, object1, name2, object2) do
     subscription
-    |> create_notification_query(name1, object1, name2, object2)
+    |> create_notification_query(user, name1, object1, name2, object2)
     |> create_notification(notification, name1)
   end
 
@@ -80,10 +81,10 @@ defmodule Philomena.Notifications.Creator do
   # TODO: the following cannot be accomplished with a single query expression
   # due to this Ecto bug: https://github.com/elixir-ecto/ecto/issues/4430
 
-  defp create_notification_query(subscription, name, object) do
+  defp create_notification_query(subscription, user, name, object) do
     now = DateTime.utc_now(:second)
 
-    from s in subscription,
+    from s in subscription_query(subscription, user),
       where: field(s, ^name) == ^object.id,
       select: %{
         ^name => type(^object.id, :integer),
@@ -94,10 +95,10 @@ defmodule Philomena.Notifications.Creator do
       }
   end
 
-  defp create_notification_query(subscription, name1, object1, name2, object2) do
+  defp create_notification_query(subscription, user, name1, object1, name2, object2) do
     now = DateTime.utc_now(:second)
 
-    from s in subscription,
+    from s in subscription_query(subscription, user),
       where: field(s, ^name1) == ^object1.id,
       select: %{
         ^name1 => type(^object1.id, :integer),
@@ -109,6 +110,19 @@ defmodule Philomena.Notifications.Creator do
       }
   end
 
+  defp subscription_query(subscription, user) do
+    case user do
+      %{id: user_id} ->
+        # Avoid sending notifications to the user which performed the action.
+        from s in subscription,
+          where: s.user_id != ^user_id
+
+      _ ->
+        # When not created by a user, send notifications to all subscribers.
+        subscription
+    end
+  end
+
   defp create_notification(query, notification, name) do
     {count, nil} =
       Repo.insert_all(

lib/philomena/posts.ex

@@ -121,14 +121,12 @@ defmodule Philomena.Posts do
   end
 
   def perform_notify(post_id) do
-    post = get_post!(post_id)
+    post =
+      post_id
+      |> get_post!()
+      |> Repo.preload([:user, :topic])
 
-    topic =
-      post
-      |> Repo.preload(:topic)
-      |> Map.fetch!(:topic)
-
-    Notifications.create_forum_post_notification(topic, post)
+    Notifications.create_forum_post_notification(post.user, post.topic, post)
   end
 
   @doc """

lib/philomena/topics.ex

@@ -91,9 +91,12 @@ defmodule Philomena.Topics do
   end
 
   def perform_notify([topic_id, _post_id]) do
-    topic = get_topic!(topic_id)
+    topic =
+      topic_id
+      |> get_topic!()
+      |> Repo.preload(:user)
 
-    Notifications.create_forum_topic_notification(topic)
+    Notifications.create_forum_topic_notification(topic.user, topic)
   end
 
   @doc """