entries_controller.rb

class EntriesController < ApplicationController
  ITEMS_PER_PAGE = 50
  def index
    subreddit = params[:subreddit].to_i
    subreddit = Subreddit.find_by_id(subreddit)
    where_filter = {}
    if subreddit
      where_filter = {
          subreddit_id: subreddit.id
      }
    end
    pages, extra = Entry.where(where_filter).count.divmod(ITEMS_PER_PAGE)
    pages += 1 if extra > 0
    page = params[:page].to_i
    page = page < 1 ? 1 : page
    skip = (page - 1) * ITEMS_PER_PAGE
    data = Entry.where(where_filter).limit(ITEMS_PER_PAGE).offset(skip).order("id DESC")
    next_page = page < pages ? page + 1 : page
    prev_page = page > 1 ? page - 1 : page
    next_page = "/entries/?page=#{next_page}"
    prev_page = "/entries/?page=#{prev_page}"
    render json: {page: page, next: next_page, prev: prev_page, data: data}
  end
end