Ruby on Rails - Different elements for each do slices

Question

In my application I do each_slice and then each_with_index because of some stuff I'm doing in my application.

My current code is like this:

- @images.each_slice(@album.images_per_page <= 2 ? 1 : 2) do |group|
  - group.each_with_index do |img, i|
    .col-md-2
      /* Ads Left */
    .col-md-7
      = image_tage img.image_url(:thumb)
    .col-md-3
      /* Ads Right */

Usually I show 4 images on every page. The first 3 will have ads inside .col-md-2 & .col-md-3 . What I want to achieve is to add different ads-codes/type for each element.

For instance, First image would have 300x250 tag , second image 300x600 and third would have content-type ads (Taboola) and not showing any ads after these 3.

I tried: (Ex. 1)

- if i == 0
  %h1 300x250
- elsif i == 1
  %h1 300x600
- elsif i == 2
  %h1 Taboola

and (Ex. 2)

- if i+1 == group.length
  %h1 i+1 = group.length

But I don't get what I'm looking for. Ex.1 takes every 1 element and adds 300x250 & every 2nd element and adds 300x600 , So I don't get Taboola and gets double of 300x250 & 300x600 while Ex.2 takes every 2nd element and adds only 300x250 .

Ex.1 results becomes this:

Image 1 => 300x250
Image 2 => 300x600
Image 3 => 300x250
Image 4 => 300x600

Ex.2 results becomes this:

Image 1 => /* Nothing */
Image 2 => 300x250
Image 3 => /* Nothing */
Image 4 => 300x250

How can I achieve so I can choose what ad I want to show on each element?

Result I'm looking for:

Image 1 => 300x250
Image 2 => 300x600
Image 3 => Taboola
Image 4 => /* Nothing */

Hope I could explain what I'm looking for.

Answer 1

The goal should be to leave as few logic as possible in views. Complex logic should be done in model/controller/helpers.

Here's a possibility with zip :

@images = %w(imageA imageB imageC imageD)

params = [
  ['300x250','r1'],
  ['300x600','r2'],
  ['Taboola','r3']
]

@images.zip(params).each_with_index do |(image, param), i|
  left, right = param
  puts "Image : #{image}"
  puts "ParamL: #{left}"
  puts "ParamR: #{right}"
  puts "Index : #{i}"
  puts "Even? : #{i.even?}"
  puts
end

It outputs :

Image : imageA
ParamL: 300x250
ParamR: r1
Index : 0
Even? : true

Image : imageB
ParamL: 300x600
ParamR: r2
Index : 1
Even? : false

Image : imageC
ParamL: Taboola
ParamR: r3
Index : 2
Even? : true

Image : imageD
ParamL: 
ParamR: 
Index : 3
Even? : false

It seems to be enough information for what you want to do.

Also, you're calling each_slice with either 1 or 2 as parameter. each_slice(1) is basically useless, each_slice(2) would just split your array in pairs. Checking if id is odd or even should give you just as much information, without needing another nested block.

each_slice(2) is also the reason why your index stays equal to 0 or 1 . It cannot be equal to 2, so your Taboola case never happened.