How to limit amount of attachments/images in view when they come out of an uploader

Question

In my Ruby on Rails project, I use a uploader for images with carrier wave and minimagick. Through my site I do use it a couple of times. But I want to limit the amount of image's on a page. Therefore the user of the cms can't upload for example more than 2 images on the homepage and 3 on the contact page.

On another answer I found an Limit, caused by the model. But I would like to determine the amount of images per page. So in my opinion this only can be done in the view for every page to approach them separately.

The code for showing images is:

<% for attachment in @page.attachments %>
<div class="painting">
  <%= image_tag attachment.image_url if attachment.image? %>
  <div class="name"><%= attachment.name %></div>
  <div class="actions">
    <%= link_to "edit", edit_attachment_path(attachment) %> |
    <%= link_to "remove", attachment, :confirm => 'Are you sure?', :method => :delete %>
  </div>
</div>

I also found this

<%= image_tag attachment.image_url[0,1] if attachment.image? %>

For showing only for example the first image, but i doesn't work anymore (it did, strangely enough).

EDIT Use in models:

page.rb

class Page < ActiveRecord::Base
attr_accessible :name, :title, :body, :image, :text1, :text2, :text3, :text4
has_many :attachments
end

event.rb

class Event < ActiveRecord::Base
attr_accessible :image, :name, :date, :description, :event_id
has_many :attachments
has_many :event_attendees 
has_many :attendees, :through => :event_attendees, :source => :user
validates_presence_of :name, :date
end

attachment.rb

class Attachment < ActiveRecord::Base
 IMAGE_SIZES = {
:default => [280, 480],
:mini => [300,900],
:home => [200, 100]
}
attr_accessible :event_id, :page_id, :name, :image, :remote_image_url, :size 
belongs_to :event
belongs_to :page    

mount_uploader :image, ImageUploader
end

Answer 1

The way I see this is as follows:

To maintain the user experience, you'd want to store unlimited attachments, and limit the number of attachments at model level (on callback)

---

Join Model

I'd have a many-to-many relationship in a polymorphic join-model, like this:

#app/models/image.rb
Class Image < ActiveRecord::Base
    has_many :image_pages
    has_many :pages, through: :image_pages
end

#app/models/image_page.rb
Class ImagePage < ActiveRecord::Base
    belongs_to :image
    belongs_to :page
end

#app/models/page.rb
Class Page < ActiveRecord::Base
    has_many :image_pages
    has_many :images, through: :image_pages, limit: :page_limits

    private
    def page_limits 
        "3" # -> put page validation here
    end
end

This will allow you to associate as many images with as many pages as you like, and also means you can limit the returned images per page

---

View

You'd call the images like this:

#app/views/pages/show.html.erb
<% @page.images.each do |image| %>
    <%= image.attachment.url %>
<% end %>

Of course you could limit at upload-level, but this would prevent the user from being able to have as many images as they like. At least by limiting on the model level, you'll be able to have as many images as you wish

Here's a good reference for you: limit the number of objects returned in a has_many

Answer 2

Solved my problem by taking the image's out of the array by this.

<% image_tag @event.attachments[1].image_url %>

With this piece of code i can pick for example image 2 (0 counts too, so this is the second image). The code is usable in a view by choice.