A better way to get paperclip thumbnail in index.html.erb - ruby-on-rails-3

Question

I've been struggling with this for hours. For some background, I have paperclip set up, keeping in mind that I may one day want to add multiple attachments. I followed Emerson's screencast to help me figure it out. (http://www.emersonlackey.com/article/paperclip-with-rails-3)
I now have this in my view, which shows what I want it to show. I had trouble for a long time because it was kicking up errors when a thumbnail didn't exist for some posts.
Anyway, wrote it, it's in my view, and I just think it's really ugly. I feel like I must be missing something. For one thing, I'm completely repeating myself on one line. Secondarily, I've got this code in my view. Is there something that I should be doing in my controller to help me keep my view cleaner?
Thanks a bunch!
<% if Asset.where(:piece_id => piece.id).first
my_asset = Asset.where(:piece_id => piece.id).first%>
<%= piece.id%>
<%= image_tag my_asset.asset.url(:thumb)%>
<% end%>
Because I haven't done anything to my controller to speak of, I'm leaving all of that code out. But here's what my models look like:
Assets
class Asset < ActiveRecord::Base
belongs_to :piece
has_attached_file :asset, :styles => {:large => ['700x700', :jpg], :medium => ['300x300>', :jpg], :thumb => ["100x100>", :jpg]}
end
Pieces
class Piece < ActiveRecord::Base
attr_accessible :assets_attributes,:name, :campaign_id,:election_date, :mail_date, :pdf_link, :photo_desc, :photo_stock, :killed, :format, :artist
belongs_to :client
has_many :assets
accepts_nested_attributes_for :assets, :allow_destroy => true
validates :campaign_id, :presence => true
end

Answer 1

So your problem is that sometimes a Piece has a thumbnail and sometimes it doesn't, right?
I'd agree that your ERB solution smells bad. You could add a thumb_nail_url method to Piece:
def thumb_nail_url
asset = assets.first
asset ? asset.asset.url(:thumb) : nil
end
And then:
<% thumb_url = piece.thumb_nail_url %>
<% if thumb_url %>
<%= image_tag thumb_url %>
<% end %>
You could also wrap the above in a helper:
def piece_thumb_image_tag(piece)
thumb_url = piece.thumb_nail_url
thumb_url ? image_tag(thumb_url) : ''
end
and then:
<%= piece_thumb_image_tag piece %>