Create Query Builder module for Post Schema

lib/diskuy/forum_post_page.ex

+defmodule Diskuy.ForumPostPage do
+  @moduledoc """
+  The Query Builder For Paging Thread Schema.
+  """
+
+  import Ecto.Query, warn: false
+  alias Diskuy.Account.User
+  alias Diskuy.Forum.Thread
+  alias Diskuy.Forum.Post
+
+  def page_per_thread(thread_id) do
+    query_start()
+    |> where([p], p.thread_id == ^thread_id)
+    |> order_by([p], asc: p.inserted_at)
+  end
+
+  defp query_start do
+    Post
+    |> join(:inner, [p], u in User, as: :users, on: p.user_id == u.id)
+    |> join(:left, [p], tr in Thread, as: :threads, on: p.thread_id == tr.id)
+    |> select([p, u], %{id: p.id, message: p.message,
+                            points: p.points,
+                            user_id: p.user_id, thread_id: p.thread_id,
+                            parent_id: p.parent_id,
+                            username: u.username, inserted_at: p.inserted_at,
+                            updated_at: p.updated_at
+                          }
+              )
+  end
+end