automatically subscribe user on post

lib/philomena/comments.ex

@@ -9,6 +9,7 @@ defmodule Philomena.Comments do
 
   alias Philomena.Comments.Comment
   alias Philomena.Images.Image
+  alias Philomena.Images
   alias Philomena.Notifications
 
   @doc """
@@ -51,6 +52,9 @@ defmodule Philomena.Comments do
     Multi.new
     |> Multi.insert(:comment, comment)
     |> Multi.update_all(:image, image_query, inc: [comments_count: 1])
+    |> Multi.run(:subscribe, fn _repo, _changes ->
+      Images.create_subscription(image, user)
+    end)
     |> Repo.transaction()
   end
 

lib/philomena/images.ex

@@ -141,6 +141,7 @@ defmodule Philomena.Images do
       {:error, %Ecto.Changeset{}}
 
   """
+  def create_subscription(image, nil), do: {:ok, nil}
   def create_subscription(image, user) do
     %Subscription{image_id: image.id, user_id: user.id}
     |> Subscription.changeset(%{})

lib/philomena/posts.ex

@@ -8,6 +8,7 @@ defmodule Philomena.Posts do
   alias Philomena.Repo
 
   alias Philomena.Topics.Topic
+  alias Philomena.Topics
   alias Philomena.Posts.Post
   alias Philomena.Forums.Forum
   alias Philomena.Notifications
@@ -75,6 +76,9 @@ defmodule Philomena.Posts do
 
       {:ok, count}
     end)
+    |> Multi.run(:subscribe, fn _repo, _changes ->
+      Topics.create_subscription(topic, user)
+    end)
     |> Repo.isolated_transaction(:serializable)
   end
 

lib/philomena/topics.ex

@@ -123,6 +123,7 @@ defmodule Philomena.Topics do
       {:error, %Ecto.Changeset{}}
 
   """
+  def create_subscription(topic, nil), do: {:ok, nil}
   def create_subscription(topic, user) do
     %Subscription{topic_id: topic.id, user_id: user.id}
     |> Subscription.changeset(%{})