Allow to mark a single notification as read

lib/pleroma/notification.ex

@@ -13,6 +13,7 @@ defmodule Pleroma.Notification do
   alias Pleroma.Web.CommonAPI.Utils
 
   import Ecto.Query
+  import Ecto.Changeset
 
   schema "notifications" do
     field(:seen, :boolean, default: false)
@@ -22,6 +23,11 @@ defmodule Pleroma.Notification do
     timestamps()
   end
 
+  def changeset(%Notification{} = notification, attrs) do
+    notification
+    |> cast(attrs, [:seen])
+  end
+
   # TODO: Make generic and unify (see activity_pub.ex)
   defp restrict_max(query, %{"max_id" => max_id}) do
     from(activity in query, where: activity.id < ^max_id)
@@ -68,6 +74,14 @@ defmodule Pleroma.Notification do
     Repo.update_all(query, [])
   end
 
+  def read_one(%User{} = user, notification_id) do
+    with {:ok, %Notification{} = notification} <- get(user, notification_id) do
+      notification
+      |> changeset(%{seen: true})
+      |> Repo.update()
+    end
+  end
+
   def get(%{id: user_id} = _user, id) do
     query =
       from(