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, table_binding \\ nil)
22 def fetch_paginated(query, %{"total" => true} = params, :keyset, table_binding) do
23 total = Repo.aggregate(query, :count, :id)
27 items: fetch_paginated(query, Map.drop(params, ["total"]), :keyset, table_binding)
31 def fetch_paginated(query, params, :keyset, table_binding) do
32 options = cast_params(params)
35 |> paginate(options, :keyset, table_binding)
37 |> enforce_order(options)
40 def fetch_paginated(query, %{"total" => true} = params, :offset, table_binding) do
43 |> Ecto.Query.exclude(:left_join)
44 |> Repo.aggregate(:count, :id)
48 items: fetch_paginated(query, Map.drop(params, ["total"]), :offset, table_binding)
52 def fetch_paginated(query, params, :offset, table_binding) do
53 options = cast_params(params)
56 |> paginate(options, :offset, table_binding)
60 def paginate(query, options, method \\ :keyset, table_binding \\ nil)
62 def paginate(query, options, :keyset, table_binding) do
64 |> restrict(:min_id, options, table_binding)
65 |> restrict(:since_id, options, table_binding)
66 |> restrict(:max_id, options, table_binding)
67 |> restrict(:order, options, table_binding)
68 |> restrict(:limit, options, table_binding)
71 def paginate(query, options, :offset, table_binding) do
73 |> restrict(:order, options, table_binding)
74 |> restrict(:offset, options, table_binding)
75 |> restrict(:limit, options, table_binding)
78 defp cast_params(params) do
89 Enum.reduce(params, %{}, fn
90 {key, _value}, acc when is_atom(key) -> Map.drop(acc, [key])
91 {key, value}, acc -> Map.put(acc, key, value)
94 changeset = cast({%{}, param_types}, params, Map.keys(param_types))
98 defp restrict(query, :min_id, %{min_id: min_id}, table_binding) do
99 where(query, [{q, table_position(query, table_binding)}], q.id > ^min_id)
102 defp restrict(query, :since_id, %{since_id: since_id}, table_binding) do
103 where(query, [{q, table_position(query, table_binding)}], q.id > ^since_id)
106 defp restrict(query, :max_id, %{max_id: max_id}, table_binding) do
107 where(query, [{q, table_position(query, table_binding)}], q.id < ^max_id)
110 defp restrict(query, :order, %{skip_order: true}, _), do: query
112 defp restrict(query, :order, %{min_id: _}, table_binding) do
115 [{u, table_position(query, table_binding)}],
116 fragment("? asc nulls last", u.id)
120 defp restrict(query, :order, _options, table_binding) do
123 [{u, table_position(query, table_binding)}],
124 fragment("? desc nulls last", u.id)
128 defp restrict(query, :offset, %{offset: offset}, _table_binding) do
129 offset(query, ^offset)
132 defp restrict(query, :limit, options, _table_binding) do
133 limit = Map.get(options, :limit, @default_limit)
139 defp restrict(query, _, _, _), do: query
141 defp enforce_order(result, %{min_id: _}) do
146 defp enforce_order(result, _), do: result
148 defp table_position(%Ecto.Query{} = query, binding_name) do
149 Map.get(query.aliases, binding_name, 0)
152 defp table_position(_, _), do: 0