Rails - How to create alphabetical system?

Question

I am getting data from my mySQL database with Ruby on Rails like that:

def all_specs
   Specialization.order("title ASC").all;
end

Now, I would like to sort this data in the view file like that:

 <div class="nav-column">
   <h3>A</h3>
    <ul class="submenu">
        <li><a href="#">All data that has title that starts with A</a></li>
    </ul>
</div>   

 <div class="nav-column">
   <h3>A</h3>
    <ul class="submenu">
        <li><a href="#">All data that has title that starts with B</a></li>
    </ul>
</div>   

and so on from A-Z

How can I achieve that ?

Answer 1

You could group the data:

specs = Specialization.order("title ASC")
specs_by_first_letter = specs.group_by { |spec| spec.title[0] }

This returns a hash like:

{
  "A" => [<Specialization title:"A...">, <Specialization title:"A...">],
  "B" => [<Specialization title:"B...">, <Specialization title:"B...">],
  ...
  "Z" => [<Specialization title:"Z...">, <Specialization title:"Z...">]
}

Looping through this hash should be quite easy. Note that some letters could be missing.

Answer 2

Thank you very much for all of your help. Zippie provided amazing solution! Here is the implementation and iterating over hash for everyone:

<% 
 institutions_c = all_institution_categories
 inst_by_first_letter = institutions_c.group_by { |inst| inst.title[0] }
%>

<% inst_by_first_letter.each do |key, value| %>
    <div class="nav-column">
          <h3><%= key %></h3>
            <ul class="submenu">
              <% value.each do |cat| %>

                  <li><%= link_to cat.title, institutions_path(:categories => cat.id), :title => cat.title %></li>

              <% end %>
            </ul>
    </div>