49 lines
1.1 KiB
Elixir
49 lines
1.1 KiB
Elixir
defmodule Mobilizon.Page do
|
|
@moduledoc """
|
|
Module for pagination of queries.
|
|
"""
|
|
|
|
import Ecto.Query, warn: false
|
|
|
|
alias Mobilizon.Repo
|
|
|
|
defstruct [
|
|
:total,
|
|
:elements
|
|
]
|
|
|
|
@type t :: %__MODULE__{
|
|
total: integer,
|
|
elements: struct
|
|
}
|
|
|
|
@doc """
|
|
Returns a Page struct for a query.
|
|
"""
|
|
@spec build_page(Ecto.Query.t(), integer | nil, integer | nil) :: t
|
|
def build_page(query, page, limit) do
|
|
[total, elements] =
|
|
[
|
|
fn -> Repo.aggregate(query, :count, :id) end,
|
|
fn -> Repo.all(paginate(query, page, limit)) end
|
|
]
|
|
|> Enum.map(&Task.async/1)
|
|
|> Enum.map(&Task.await/1)
|
|
|
|
%__MODULE__{total: total, elements: elements}
|
|
end
|
|
|
|
@doc """
|
|
Add limit and offset to the query.
|
|
"""
|
|
@spec paginate(Ecto.Query.t(), integer | nil, integer | nil) :: Ecto.Query.t()
|
|
def paginate(query, page \\ 1, size \\ 10)
|
|
|
|
def paginate(query, page, _size) when is_nil(page), do: paginate(query)
|
|
def paginate(query, page, size) when is_nil(size), do: paginate(query, page)
|
|
|
|
def paginate(query, page, size) do
|
|
from(query, limit: ^size, offset: ^((page - 1) * size))
|
|
end
|
|
end
|