Understanding "@books = Book.all.page params[:page]" in Ruby on Rails

Question

looooong time reader and knowledge attainer, first time poster. I've started learning Rails and I definitely need help.

I am following a tutorial with this code:

class BooksController < ApplicationController
  def index
    if params[:query].present?
      @books = Book.search(params[:query], page: params[:page])
    else
      @books = Book.all.page params[:page]
    end
  end

And I am trying to apply this to my own project (I have 'destinations' not 'books'). What I don't understand is what is the .page parameter and where is it generated from?

I am getting an "undefined method "page" on my Controller and I don't understand what it is.

This is my code:

class DestinationsController < ApplicationController
def index
    if params[:query].present?
      @destination = Destination.search(params[:query], page: params[:page])
    else
      @destination = Destination.all.page params[:page]
    end
  end

The only field I have in the Destinations table is country. I thought maybe that could replace it but alas, no. Yes, I'm very new to this. Any help is appreciated.

That is from ***pagination gems*** either `will_paginate` or `kaminari` — Pavan, Jul 04 '15 at 14:08
Thank you, you pointed me in the right direction but after many hours, there was a space in a link to a javascript file causing the main issue. However, thank you I now know about pagination parameters! :) — user2809852, Jul 04 '15 at 15:14

score 1 · Accepted Answer · answered Jul 04 '15 at 14:54

1

How deep is your programming knowledge, especially Ruby one?

The tutorial is clearly using a pagination gem, I'll take kaminari because it's the one I use.

The gem monkey patches relation to include the method page and per, and as you can clearly see in Kaminari homepage, the method simply accepts page(page_number) and will take care to split your records using SQL LIMIT and OFFSET. The params[:page] will be a simple HTTP GET param ?page=12.

I notice you are also using Destination.search, that's not standard, did you create it? If yes, it should probably be something like Destination.search(params[:query]).page(params[:page]). If however it's using something like meta_search (which you shouldn't) or ransack, they are quite advanced and you should check for compatibility with Kaminari, which I'm quite sure it's present in Ransack

answered Jul 04 '15 at 14:54

Francesco Belladonna

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Thanks @Fire-Dragon-DoL... I am a frontend developer and this is my first forray into the deep mysteries of the backend. As far as I can see, I have used: 'Destination.search(params[:query]).page(params[:page])' unless I am not understanding you. Thanks for the tips and yes I assumed it was pagination but didn't mention it. – user2809852 Jul 04 '15 at 18:08
From the code I'm seeing no, you didn't use `search.page`, in your question you clearly write `Book.search(params[:query], page: params[:page])` (page passed as param, not chained). To use it with Ransack, which I suppose you are using, check this answer: http://stackoverflow.com/a/17463115/312907 In the end, it's your choice if you want pagination for those records or not. If yes, you should add `gem 'kaminari'` to your Gemfile at least and fix the pagination for ransack as I suggested – Francesco Belladonna Jul 04 '15 at 19:58
"page passed as param, not chained". I see that now. I have a lot to learn. Thank you for the help. – user2809852 Jul 04 '15 at 20:48

Understanding "@books = Book.all.page params[:page]" in Ruby on Rails

1 Answers1