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Elixir Phoenix pagination module from https://blog.drewolson.org/pagination-with-phoenix-ecto/
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defmodule Infra.Paginator do | |
import Ecto.Query | |
alias Infra.Repo | |
defstruct [:entries, :page, :size, :total] | |
def new(query, params) do | |
page_number = params |> Map.get("page", 1) |> to_int | |
page_size = params |> Map.get("size", 10) |> to_int | |
%Infra.Paginator{ | |
entries: entries(query, page_number, page_size), | |
page: page_number, | |
size: page_size, | |
total: total_pages(query, page_size) | |
} | |
end | |
defp entries(query, page_number, page_size) do | |
offset = page_size * (page_number - 1) | |
query | |
|> limit(^page_size) | |
|> offset(^offset) | |
|> Repo.all() | |
end | |
defp to_int(i) when is_integer(i), do: i | |
defp to_int(s) when is_binary(s) do | |
case Integer.parse(s) do | |
{i, _} -> i | |
:error -> :error | |
end | |
end | |
defp total_pages(query, page_size) do | |
count = | |
query | |
|> exclude(:order_by) | |
|> exclude(:preload) | |
|> exclude(:select) | |
|> select([e], count(e.id)) | |
|> Repo.one() | |
trunc(Float.ceil(count / page_size)) | |
end | |
end |
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