1 # Pleroma: A lightweight social networking server
2 # Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
3 # SPDX-License-Identifier: AGPL-3.0-only
5 defmodule Pleroma.Pagination do
7 Implements Mastodon-compatible pagination.
17 def fetch_paginated(query, params) do
18 options = cast_params(params)
23 |> enforce_order(options)
26 def paginate(query, options) do
28 |> restrict(:min_id, options)
29 |> restrict(:since_id, options)
30 |> restrict(:max_id, options)
31 |> restrict(:order, options)
32 |> restrict(:limit, options)
35 defp cast_params(params) do
44 Enum.reduce(params, %{}, fn
45 {key, _value}, acc when is_atom(key) -> Map.drop(acc, [key])
46 {key, value}, acc -> Map.put(acc, key, value)
49 changeset = cast({%{}, param_types}, params, Map.keys(param_types))
53 defp restrict(query, :min_id, %{min_id: min_id}) do
54 where(query, [q], q.id > ^min_id)
57 defp restrict(query, :since_id, %{since_id: since_id}) do
58 where(query, [q], q.id > ^since_id)
61 defp restrict(query, :max_id, %{max_id: max_id}) do
62 where(query, [q], q.id < ^max_id)
65 defp restrict(query, :order, %{min_id: _}) do
66 order_by(query, [u], fragment("? asc nulls last", u.id))
69 defp restrict(query, :order, _options) do
70 order_by(query, [u], fragment("? desc nulls last", u.id))
73 defp restrict(query, :limit, options) do
74 limit = Map.get(options, :limit, @default_limit)
80 defp restrict(query, _, _), do: query
82 defp enforce_order(result, %{min_id: _}) do
87 defp enforce_order(result, _), do: result