Ability to publish and unpublish polls

lib/ex_poll/polls.ex

@@ -4,9 +4,9 @@ defmodule ExPoll.Polls do
   """
 
   import Ecto.Query, warn: false
+  alias Ecto.Multi
   alias ExPoll.Repo
-
-  alias ExPoll.Polls.{Poll, Option}
+  alias ExPoll.Polls.{Poll, Option, Vote}
 
   # POLL
 
@@ -43,6 +43,32 @@ defmodule ExPoll.Polls do
     Repo.delete(poll)
   end
 
+  def publish_poll(%Poll{} = poll) do
+    poll
+    |> Poll.publish_changeset()
+    |> Repo.update()
+  end
+
+  def unpublish_poll(%Poll{} = poll) do
+    poll_changeset = Poll.unpublish_changeset(poll)
+    option_ids = Enum.map(poll.options, fn option -> option.id end)
+    poll_votes_query = from(v in Vote, where: v.option_id in ^option_ids)
+
+    result =
+      Multi.new()
+      |> Multi.update(:update_poll, poll_changeset)
+      |> Multi.delete_all(:delete_votes, poll_votes_query)
+      |> Repo.transaction()
+
+    case result do
+      {:ok, %{update_poll: poll}} ->
+        {:ok, get_poll!(poll.id)}
+
+      {:error, _failed_operation, _failed_value, _changes_so_far} ->
+        {:error, "Something went wrong while unpublishing a poll"}
+    end
+  end
+
   def change_poll(%Poll{} = poll, attrs \\ %{}) do
     Poll.changeset(poll, attrs)
   end
@@ -59,14 +85,15 @@ defmodule ExPoll.Polls do
   def get_option!(id) do
     query =
       from o in options_query(),
-        where: o.id == ^id
+        where: o.id == ^id,
+        preload: [:poll]
 
     Repo.one!(query)
   end
 
   def create_option(%Poll{} = poll, attrs \\ %{}) do
     poll
-    |> Ecto.build_assoc(:options)
+    |> Ecto.build_assoc(:options, poll: poll)
     |> Option.changeset(attrs)
     |> Repo.insert()
   end
@@ -78,7 +105,9 @@ defmodule ExPoll.Polls do
   end
 
   def delete_option(%Option{} = option) do
-    Repo.delete(option)
+    option
+    |> change_option()
+    |> Repo.delete()
   end
 
   def change_option(%Option{} = option, attrs \\ %{}) do
@@ -89,7 +118,12 @@ defmodule ExPoll.Polls do
 
   def create_vote(%Option{} = option) do
     option
-    |> Ecto.build_assoc(:votes)
+    |> Ecto.build_assoc(:votes, option: option)
+    |> change_vote()
     |> Repo.insert()
   end
+
+  def change_vote(%Vote{} = vote, attrs \\ %{}) do
+    Vote.changeset(vote, attrs)
+  end
 end

lib/ex_poll/polls/option.ex

@@ -18,5 +18,15 @@ defmodule ExPoll.Polls.Option do
     |> cast(attrs, [:value])
     |> validate_required([:value])
     |> assoc_constraint(:poll)
+    |> validate_poll_is_not_published()
+  end
+
+  defp validate_poll_is_not_published(changeset) do
+    poll = get_field(changeset, :poll)
+
+    case poll.is_published do
+      true -> add_error(changeset, :is_published, "poll can't be modified when it's published")
+      false -> changeset
+    end
   end
 end

lib/ex_poll/polls/poll.ex

@@ -5,6 +5,7 @@ defmodule ExPoll.Polls.Poll do
 
   schema "polls" do
     field :question, :string
+    field :is_published, :boolean, default: false
     timestamps()
 
     has_many(:options, Option, on_replace: :delete)
@@ -16,5 +17,35 @@ defmodule ExPoll.Polls.Poll do
     |> cast(attrs, [:question])
     |> cast_assoc(:options)
     |> validate_required([:question])
+    |> validate_poll_is_not_published()
+  end
+
+  def publish_changeset(poll) do
+    poll
+    |> cast(%{is_published: true}, [:is_published])
+    |> validate_min_options_count()
+  end
+
+  def unpublish_changeset(poll) do
+    poll
+    |> cast(%{is_published: false}, [:is_published])
+  end
+
+  defp validate_poll_is_not_published(changeset) do
+    is_published = get_field(changeset, :is_published)
+
+    case is_published do
+      true -> add_error(changeset, :is_published, "poll can't be modified when it's published")
+      false -> changeset
+    end
+  end
+
+  defp validate_min_options_count(changeset, count \\ 2) do
+    options = get_field(changeset, :options, [])
+
+    case length(options) >= count do
+      true -> changeset
+      false -> add_error(changeset, :options, "should have at least #{count} option(s)")
+    end
   end
 end

lib/ex_poll/polls/vote.ex

@@ -14,6 +14,15 @@ defmodule ExPoll.Polls.Vote do
     vote
     |> cast(attrs, [])
     |> validate_required([])
-    |> assoc_constraint(:option)
+    |> validate_poll_is_published()
+  end
+
+  defp validate_poll_is_published(changeset) do
+    option = get_field(changeset, :option)
+
+    case option.poll.is_published do
+      true -> changeset
+      false -> add_error(changeset, :is_published, "poll can't be voted on when it's unpublished")
+    end
   end
 end

lib/ex_poll_web/controllers/poll_controller.ex

@@ -40,4 +40,20 @@ defmodule ExPollWeb.PollController do
       send_resp(conn, :no_content, "")
     end
   end
+
+  def publish(conn, %{"id" => id}) do
+    poll = Polls.get_poll!(id)
+
+    with {:ok, %Poll{} = poll} <- Polls.publish_poll(poll) do
+      render(conn, "show.json", poll: poll)
+    end
+  end
+
+  def unpublish(conn, %{"id" => id}) do
+    poll = Polls.get_poll!(id)
+
+    with {:ok, %Poll{} = poll} <- Polls.unpublish_poll(poll) do
+      render(conn, "show.json", poll: poll)
+    end
+  end
 end

lib/ex_poll_web/router.ex

@@ -13,6 +13,8 @@ defmodule ExPollWeb.Router do
     end
 
     post("/polls/:id/vote", VoteController, :create)
+    post("/polls/:id/publish", PollController, :publish)
+    post("/polls/:id/unpublish", PollController, :unpublish)
   end
 
   # Enables LiveDashboard only for development

lib/ex_poll_web/views/poll_view.ex

@@ -13,14 +13,16 @@ defmodule ExPollWeb.PollView do
   def render("poll.json", %{poll: poll}) do
     %{
       id: poll.id,
-      question: poll.question
+      question: poll.question,
+      is_publised: poll.is_published
     }
   end
 
   def render("poll_with_options.json", %{poll: poll}) do
     %{
       id: poll.id,
       question: poll.question,
+      is_publised: poll.is_published,
       options: render_many(poll.options, OptionView, "option.json")
     }
   end

priv/repo/migrations/20200814130356_update_polls_table.exs

@@ -0,0 +1,9 @@
+defmodule ExPoll.Repo.Migrations.UpdatePollsTable do
+  use Ecto.Migration
+
+  def change do
+    alter table(:polls) do
+      add :is_published, :boolean, default: false
+    end
+  end
+end