130 lines
3 KiB
Elixir
130 lines
3 KiB
Elixir
# Pleroma: A lightweight social networking server
|
|
# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
|
|
# SPDX-License-Identifier: AGPL-3.0-only
|
|
|
|
defmodule Pleroma.Pagination do
|
|
@moduledoc """
|
|
Implements Mastodon-compatible pagination.
|
|
"""
|
|
|
|
import Ecto.Query
|
|
import Ecto.Changeset
|
|
|
|
alias Pleroma.Repo
|
|
|
|
@default_limit 20
|
|
|
|
def fetch_paginated(query, params, type \\ :keyset)
|
|
|
|
def fetch_paginated(query, %{"total" => true} = params, :keyset) do
|
|
total = Repo.aggregate(query, :count, :id)
|
|
|
|
%{
|
|
total: total,
|
|
items: fetch_paginated(query, Map.drop(params, ["total"]), :keyset)
|
|
}
|
|
end
|
|
|
|
def fetch_paginated(query, params, :keyset) do
|
|
options = cast_params(params)
|
|
|
|
query
|
|
|> paginate(options, :keyset)
|
|
|> Repo.all()
|
|
|> enforce_order(options)
|
|
end
|
|
|
|
def fetch_paginated(query, %{"total" => true} = params, :offset) do
|
|
total = Repo.aggregate(query, :count, :id)
|
|
|
|
%{
|
|
total: total,
|
|
items: fetch_paginated(query, Map.drop(params, ["total"]), :offset)
|
|
}
|
|
end
|
|
|
|
def fetch_paginated(query, params, :offset) do
|
|
options = cast_params(params)
|
|
|
|
query
|
|
|> paginate(options, :offset)
|
|
|> Repo.all()
|
|
end
|
|
|
|
def paginate(query, options, method \\ :keyset)
|
|
|
|
def paginate(query, options, :keyset) do
|
|
query
|
|
|> restrict(:min_id, options)
|
|
|> restrict(:since_id, options)
|
|
|> restrict(:max_id, options)
|
|
|> restrict(:order, options)
|
|
|> restrict(:limit, options)
|
|
end
|
|
|
|
def paginate(query, options, :offset) do
|
|
query
|
|
|> restrict(:order, options)
|
|
|> restrict(:offset, options)
|
|
|> restrict(:limit, options)
|
|
end
|
|
|
|
defp cast_params(params) do
|
|
param_types = %{
|
|
min_id: :string,
|
|
since_id: :string,
|
|
max_id: :string,
|
|
offset: :integer,
|
|
limit: :integer
|
|
}
|
|
|
|
params =
|
|
Enum.reduce(params, %{}, fn
|
|
{key, _value}, acc when is_atom(key) -> Map.drop(acc, [key])
|
|
{key, value}, acc -> Map.put(acc, key, value)
|
|
end)
|
|
|
|
changeset = cast({%{}, param_types}, params, Map.keys(param_types))
|
|
changeset.changes
|
|
end
|
|
|
|
defp restrict(query, :min_id, %{min_id: min_id}) do
|
|
where(query, [q], q.id > ^min_id)
|
|
end
|
|
|
|
defp restrict(query, :since_id, %{since_id: since_id}) do
|
|
where(query, [q], q.id > ^since_id)
|
|
end
|
|
|
|
defp restrict(query, :max_id, %{max_id: max_id}) do
|
|
where(query, [q], q.id < ^max_id)
|
|
end
|
|
|
|
defp restrict(query, :order, %{min_id: _}) do
|
|
order_by(query, [u], fragment("? asc nulls last", u.id))
|
|
end
|
|
|
|
defp restrict(query, :order, _options) do
|
|
order_by(query, [u], fragment("? desc nulls last", u.id))
|
|
end
|
|
|
|
defp restrict(query, :offset, %{offset: offset}) do
|
|
offset(query, ^offset)
|
|
end
|
|
|
|
defp restrict(query, :limit, options) do
|
|
limit = Map.get(options, :limit, @default_limit)
|
|
|
|
query
|
|
|> limit(^limit)
|
|
end
|
|
|
|
defp restrict(query, _, _), do: query
|
|
|
|
defp enforce_order(result, %{min_id: _}) do
|
|
result
|
|
|> Enum.reverse()
|
|
end
|
|
|
|
defp enforce_order(result, _), do: result
|
|
end
|