I often want to display an array of objects as a table on a page, and I end up doing the the same things over and over again. I wrote this helper method to speed things up:

   1  
   2  def table(collection, headers, options = {}, &proc)
   3    options.reverse_merge!({
   4      :placeholder  => 'Nothing to display',
   5      :caption      => nil,
   6      :summary      => nil,
   7      :footer       => ''
   8    })
   9    placeholder_unless collection.any?, options[:placeholder] do
  10      summary = options[:summary] || "A list of #{collection.first.class.to_s.pluralize}"
  11      output = "<table summary=\"#{summary}\">\n"
  12      output << content_tag('caption', options[:caption]) if options[:caption]
  13      output << "\t<caption>#{options[:caption]}</caption>\n" if options[:caption]
  14      output << content_tag('thead', content_tag('tr', headers.collect { |h| "\n\t" + content_tag('th', h) }))
  15      output << "<tfoot><tr>" + content_tag('th', options[:footer], :colspan => headers.size) + "</tr></tfoot>\n" if options[:footer]
  16      output << "<tbody>\n"
  17      concat(output, proc.binding)
  18      collection.each do |row|
  19        proc.call(row, cycle('odd', 'even'))
  20      end
  21      concat("</tbody>\n</table>\n", proc.binding)
  22    end
  23  end

Writing...

   1  
   2  <% table(@posts, %w{ID title}) do |post, klass| -%>
   3      <tr class="<%= klass %>">
   4        <td><%= post.id</td>
   5        <td><%= post.title </td>
   6      </tr>
   7  <% end -%>

results in...

   1  
   2  <table summary="A list of posts">
   3    <thead>
   4      <tr>
   5        <th>ID</th>
   6        <th>Title</th>
   7      </tr>
   8    </thead>
   9    <tfoot><tr><td colspan="2"></td></tr></tfoot>
  10    <tbody>
  11      <tr>
  12        <td>1</td>
  13        <td>My first post</td>
  14      </tr>
  15    </tbody>
  16  </table>

Or, when the collection is an empty array (collection.any? returns false), a placeholder message is displayed:

   1  
   2  <p class="placeholder">Nothing to display</p>

So you pass in your collection and an array of strings as your table headers as the first two arguments, and the third is a hash of options you can use to set the contents of the table's summary-attribute, the caption and footer-elements and the placeholder.

The summary attribute defaults to "A list of [objects]", where 'objects' is derived from the class name of the collection.

The function finally takes a block for every element in the collection, yeilding it the element and either 'odd' or 'even' so you can use CSS-classes to apply a zebra stripes effect.