Scrivener

Scrivener allows you to paginate your Ecto queries. It gives you useful information such as the total number of pages, the current page, and the current page’s entries. It works nicely with Phoenix as well.

First, you’ll want to use Scrivener in your application’s Repo. This will add a paginate function to your Repo. This paginate function expects to be called with, at a minimum, an Ecto query. It will then paginate the query and execute it, returning a Scrivener.Page. Defaults for page_size can be configued when you use Scrivener. If no page_size is provided, Scrivener will use 10 by default.

You may also want to call paginate with a params map along with your query. If provided with a params map, Scrivener will use the values in the keys "page" and "page_size" before using any configured defaults.

Example

defmodule MyApp.Repo do
  use Ecto.Repo, otp_app: :my_app
  use Scrivener, page_size: 10
end

defmodule MyApp.Person do
  use Ecto.Model

  schema "people" do
    field :name, :string
    field :age, :integer

    has_many :friends, MyApp.Person
  end
end

def index(conn, params) do
  page = MyApp.Person
  |> where([p], p.age > 30)
  |> order_by([p], desc: p.age)
  |> preload(:friends)
  |> MyApp.Repo.paginate(params)

  render conn, :index,
    people: page.entries,
    page_number: page.page_number,
    page_size: page.page_size,
    total_pages: page.total_pages,
    total_entries: page.total_entries
end

page = MyApp.Person
|> where([p], p.age > 30)
|> order_by([p], desc: p.age)
|> preload(:friends)
|> MyApp.Repo.paginate(page: 2, page_size: 5)

Installation

Add scrivener to your mix.exs dependencies.

defp deps do
  [{:scrivener, "~> 0.12.0"}]
end

Contributing

First, you’ll need to build the test database.

MIX_ENV=test mix scrivener.db.reset

This task assumes you have postgres installed and that your current user can create / drop databases. If you’d prefer to use a different user, you can specify it with the environment variable SCRIVENER_DB_USER.

With the database built, you can now run the tests.

mix test