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Helper For Quicly Creating Standard Tables

03.03.2007
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        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:

def table(collection, headers, options = {}, &proc)
  options.reverse_merge!({
    :placeholder  => 'Nothing to display',
    :caption      => nil,
    :summary      => nil,
    :footer       => ''
  })
  placeholder_unless collection.any?, options[:placeholder] do
    summary = options[:summary] || "A list of #{collection.first.class.to_s.pluralize}"
    output = "<table summary=\"#{summary}\">\n"
    output << content_tag('caption', options[:caption]) if options[:caption]
    output << "\t<caption>#{options[:caption]}</caption>\n" if options[:caption]
    output << content_tag('thead', content_tag('tr', headers.collect { |h| "\n\t" + content_tag('th', h) }))
    output << "<tfoot><tr>" + content_tag('th', options[:footer], :colspan => headers.size) + "</tr></tfoot>\n" if options[:footer]
    output << "<tbody>\n"
    concat(output, proc.binding)
    collection.each do |row|
      proc.call(row, cycle('odd', 'even'))
    end
    concat("</tbody>\n</table>\n", proc.binding)
  end
end

Writing...

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

results in...

<table summary="A list of posts">
  <thead>
    <tr>
      <th>ID</th>
      <th>Title</th>
    </tr>
  </thead>
  <tfoot><tr><td colspan="2"></td></tr></tfoot>
  <tbody>
    <tr>
      <td>1</td>
      <td>My first post</td>
    </tr>
  </tbody>
</table>

Or, when the collection is an empty array (collection.any? returns false), a <a href="http://snippets.dzone.com/posts/show/2929">placeholder message</a> is displayed:

<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.