[LRUG] Funny gotcha with blocks in partials.

[Chris Mear]

On 22 Jun 2009, at 16:31, Tim Cowlishaw wrote:

> However, if i pass it a block that contains ERB template strings, it  
> breaks - it just returns the result of each call to the block direct  
> to the template being rendered, as it's executed, rather than  
> returning it as the result of the call to array_to_list itself:
>
> <% array_to_list(@flash_games, :class => "flash_games_grid") do | 
> game, array| %>
>        <a href="<%= game_path(:id => game.id) %>"><img src="<%=  
> game.image_url(:grid) %>" alt="A Game" width="128" height="128" /></a>
> <% end %>
>
> I have a suspicion that this is something the rails capture() method  
> might be needed for, but i'm struggling to understand how, Anyone  
> seen anything similar in the past?

Yeah, I've done something like this before, by building up the output  
using the concat method, and using capture to get the rendered results  
of blocks defined in the ERB template. Something like this should work:

   def array_to_list(data, opts={}, array=nil, &block)
     array ||= data #pass the top level data structure down the stack.
     if data.is_a?(Array)
       concat('<ul>')
       data.each do |e|
         concat('<li>')
         array_to_list(e, opts, array, &block)
         concat('</li>')
       end
       concat('</ul>')
     else
       concat(block ? capture(data, array, &block) : data.to_s)
     end
   end

Making this less ugly-as-sin is left as an exercise to the reader.

Chris