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, type \\ :keyset)
19 def fetch_paginated(query, params, :keyset) do
20 options = cast_params(params)
23 |> paginate(options, :keyset)
25 |> enforce_order(options)
28 def fetch_paginated(query, params, :offset) do
29 options = cast_params(params)
32 |> paginate(options, :offset)
36 def paginate(query, options, method \\ :keyset)
38 def paginate(query, options, :keyset) do
40 |> restrict(:min_id, options)
41 |> restrict(:since_id, options)
42 |> restrict(:max_id, options)
43 |> restrict(:order, options)
44 |> restrict(:limit, options)
47 def paginate(query, options, :offset) do
49 |> restrict(:offset, options)
50 |> restrict(:limit, options)
53 defp cast_params(params) do
63 Enum.reduce(params, %{}, fn
64 {key, _value}, acc when is_atom(key) -> Map.drop(acc, [key])
65 {key, value}, acc -> Map.put(acc, key, value)
68 changeset = cast({%{}, param_types}, params, Map.keys(param_types))
72 defp restrict(query, :min_id, %{min_id: min_id}) do
73 where(query, [q], q.id > ^min_id)
76 defp restrict(query, :since_id, %{since_id: since_id}) do
77 where(query, [q], q.id > ^since_id)
80 defp restrict(query, :max_id, %{max_id: max_id}) do
81 where(query, [q], q.id < ^max_id)
84 defp restrict(query, :order, %{min_id: _}) do
85 order_by(query, [u], fragment("? asc nulls last", u.id))
88 defp restrict(query, :order, _options) do
89 order_by(query, [u], fragment("? desc nulls last", u.id))
92 defp restrict(query, :offset, %{offset: offset}) do
93 offset(query, ^offset)
96 defp restrict(query, :limit, options) do
97 limit = Map.get(options, :limit, @default_limit)
103 defp restrict(query, _, _), do: query
105 defp enforce_order(result, %{min_id: _}) do
110 defp enforce_order(result, _), do: result