Limit/offset pagination for Ecto queries.

BoxTurtle.Schema.Query applies it for the :page option, so you rarely call it directly. It also works on any Ecto query. A page is either a page number, using the default size, or a keyword list:

import Ecto.Query
alias BoxTurtle.Schema.Pagination

query = from(p in MyApp.Blog.Post, order_by: [desc: p.inserted_at, desc: p.id])

# Second page of 40 rows (the default size): LIMIT 40 OFFSET 40
query |> Pagination.page(2) |> MyApp.Repo.all()

# Rows 11-20: LIMIT 10 OFFSET 10
query |> Pagination.page(number: 2, size: 10) |> MyApp.Repo.all()

Page numbers below 1 are treated as 1. Give the query an order_by ending in a unique column, so rows don't move between pages.