Remove Repo fetch from Channel module

lib/philomena/channels.ex

@@ -8,6 +8,7 @@ defmodule Philomena.Channels do
 
   alias Philomena.Channels.AutomaticUpdater
   alias Philomena.Channels.Channel
+  alias Philomena.Tags
 
   use Philomena.Subscriptions,
     actor_types: ~w(Channel LivestreamChannel),
@@ -50,6 +51,7 @@ defmodule Philomena.Channels do
   """
   def create_channel(attrs \\ %{}) do
     %Channel{}
+    |> update_artist_tag(attrs)
     |> Channel.changeset(attrs)
     |> Repo.insert()
   end
@@ -68,10 +70,29 @@ defmodule Philomena.Channels do
   """
   def update_channel(%Channel{} = channel, attrs) do
     channel
+    |> update_artist_tag(attrs)
     |> Channel.changeset(attrs)
     |> Repo.update()
   end
 
+  @doc """
+  Adds the artist tag from the `"artist_tag"` tag name attribute.
+
+  ## Examples
+
+      iex> update_artist_tag(%Channel{}, %{"artist_tag" => "artist:nighty"})
+      %Ecto.Changeset{}
+
+  """
+  def update_artist_tag(%Channel{} = channel, attrs) do
+    tag =
+      attrs
+      |> Map.get("artist_tag", "")
+      |> Tags.get_tag_by_name()
+
+    Channel.artist_tag_changeset(channel, tag)
+  end
+
   @doc """
   Updates a channel's state when it goes live.
 

lib/philomena/channels/channel.ex

@@ -3,7 +3,6 @@ defmodule Philomena.Channels.Channel do
   import Ecto.Changeset
 
   alias Philomena.Tags.Tag
-  alias Philomena.Repo
 
   schema "channels" do
     belongs_to :associated_artist_tag, Tag
@@ -36,19 +35,13 @@ defmodule Philomena.Channels.Channel do
 
   @doc false
   def changeset(channel, attrs) do
-    tag_id =
-      case Repo.get_by(Tag, name: attrs["artist_tag"] || "") do
-        %{id: id} -> id
-        _ -> nil
-      end
-
     channel
     |> cast(attrs, [:type, :short_name])
     |> validate_required([:type, :short_name])
     |> validate_inclusion(:type, ["PicartoChannel", "PiczelChannel"])
-    |> put_change(:associated_artist_tag_id, tag_id)
   end
 
+  @doc false
   def update_changeset(channel, attrs) do
     cast(channel, attrs, [
       :title,
@@ -60,4 +53,11 @@ defmodule Philomena.Channels.Channel do
       :last_live_at
     ])
   end
+
+  @doc false
+  def artist_tag_changeset(channel, tag) do
+    tag_id = Map.get(tag || %{}, :id)
+
+    change(channel, associated_artist_tag_id: tag_id)
+  end
 end

lib/philomena/tags.ex

@@ -81,6 +81,22 @@ defmodule Philomena.Tags do
   """
   def get_tag!(id), do: Repo.get!(Tag, id)
 
+  @doc """
+  Gets a single tag.
+
+  Returns nil if the Tag does not exist.
+
+  ## Examples
+
+      iex> get_tag_by_name("safe")
+      %Tag{}
+
+      iex> get_tag_by_name("nonexistent")
+      nil
+
+  """
+  def get_tag_by_name(name), do: Repo.get_by(Tag, name: name)
+
   @doc """
   Gets a single tag by its name, or the tag it is aliased to, if it is aliased.