nicolasblanco · August 21, 2022 16:38 · Aug 21, 2022
diff --git a/pagination.ex b/pagination.ex
@@ -0,0 +1,41 @@
+defmodule Pagination do
+  import Ecto.Query
+  alias Snippets.Repo
+  #
+  # ## Example
+  #
+  #    Snippets.Snippet
+  #    |> order_by(desc: :inserted_at)
+  #    |> Pagination.page(0, per_page: 10)
+  #
+  def page(query, page, per_page: per_page) when is_nil(page) do
+    page(query, 0, per_page: per_page)
+  end
+
+  def page(query, page, per_page: per_page) when is_binary(page) do
+    page = String.to_integer(page)
+    page(query, page, per_page: per_page)
+  end
+
+  def page(query, page, per_page: per_page) do
+    count = per_page + 1
+    result = query
+             |> limit(^count)
+             |> offset(^(page*per_page))
+             |> Repo.all
+    has_next = (length(result) == count)
+    has_prev = page > 0
+    total_count = Repo.one(from t in subquery(query), select: count("*"))
+    page = %{
+      has_next: has_next,
+      has_prev: has_prev,
+      prev_page: page - 1,
+      next_page: page + 1,
+      page: page,
+      first: page*per_page+1,
+      last: Enum.min([page+1*per_page, total_count]),
+      count: total_count,
+      list: Enum.slice(result, 0, count-1)
+    }
+  end
+end