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.
16 @page_keys ["max_id", "min_id", "limit", "since_id", "order"]
18 def page_keys, do: @page_keys
20 def fetch_paginated(query, params, type \\ :keyset)
22 def fetch_paginated(query, %{"total" => true} = params, :keyset) do
23 total = Repo.aggregate(query, :count, :id)
27 items: fetch_paginated(query, Map.drop(params, ["total"]), :keyset)
31 def fetch_paginated(query, params, :keyset) do
32 options = cast_params(params)
35 |> paginate(options, :keyset)
37 |> enforce_order(options)
40 def fetch_paginated(query, %{"total" => true} = params, :offset) do
41 total = Repo.aggregate(query, :count, :id)
45 items: fetch_paginated(query, Map.drop(params, ["total"]), :offset)
49 def fetch_paginated(query, params, :offset) do
50 options = cast_params(params)
53 |> paginate(options, :offset)
57 def paginate(query, options, method \\ :keyset)
59 def paginate(query, options, :keyset) do
61 |> restrict(:min_id, options)
62 |> restrict(:since_id, options)
63 |> restrict(:max_id, options)
64 |> restrict(:order, options)
65 |> restrict(:limit, options)
68 def paginate(query, options, :offset) do
70 |> restrict(:order, options)
71 |> restrict(:offset, options)
72 |> restrict(:limit, options)
75 defp cast_params(params) do
85 Enum.reduce(params, %{}, fn
86 {key, _value}, acc when is_atom(key) -> Map.drop(acc, [key])
87 {key, value}, acc -> Map.put(acc, key, value)
90 changeset = cast({%{}, param_types}, params, Map.keys(param_types))
94 defp restrict(query, :min_id, %{min_id: min_id}) do
95 where(query, [q], q.id > ^min_id)
98 defp restrict(query, :since_id, %{since_id: since_id}) do
99 where(query, [q], q.id > ^since_id)
102 defp restrict(query, :max_id, %{max_id: max_id}) do
103 where(query, [q], q.id < ^max_id)
106 defp restrict(query, :order, %{min_id: _}) do
107 order_by(query, [u], fragment("? asc nulls last", u.id))
110 defp restrict(query, :order, _options) do
111 order_by(query, [u], fragment("? desc nulls last", u.id))
114 defp restrict(query, :offset, %{offset: offset}) do
115 offset(query, ^offset)
118 defp restrict(query, :limit, options) do
119 limit = Map.get(options, :limit, @default_limit)
125 defp restrict(query, _, _), do: query
127 defp enforce_order(result, %{min_id: _}) do
132 defp enforce_order(result, _), do: result