Question

I got this very weird problem this evening when I was building something like “filter-posts-by-multiple-tags” feature.

In the view template:

<%
tags = Tag.all
selected_tags ||= nil
%>

<ul>
    <% tags.each do |tag| %>
    <% logger.info("selected_tags size:"+ selected_tags.size.inspect) %>
    <li><%= link_or_span(tag, selected_tags) %></li>
    <% end %>
</ul>

In the TagsHelper:

module TagsHelper
  def link_or_span(tag, selected_tags)
    selected_tags.delete(tag)
    link_to tag.title, tag
  end
end

It outputs (in the log):

selected_tags size:2
selected_tags size:1
selected_tags size:0

What I expect:

selected_tags size:2
selected_tags size:2
selected_tags size:2

I think var “selected_tags” in the view template should be untouched each time in the loop since it’s in the different scope, isn’t it?

The ENV:

• ruby 1.9.2p180 (2011-02-18 revision 30909) [x86_64-linux]
• Rails 3.1.0.rc4

Answer 1

selected_tags.delete(tag)

replace to

selected_tags.map {|t| tag.delete(t) }

because I think your code will show all tag without selected_tag?it is right