blackrat.org

Last time, I built a standard scaffolded Rails application with a modified database, controller (admin) controlling a model named programme. The next step is to add a view and import mechanism. The standard scaffold mechanism uses a list.rhtml as the entry point, so we will create one of these to override the scaffold, and display a list of the current programmes, along with the import button.

<h1>Listing programmes</h1>
  <table>
    <tr>
      <% for column in Programme.content_columns %>
        <th><%= column.human_name %></th>
      <% end %>
    </tr>
    <% for programme in @programmes %>
      <tr>
        <% for column in Programme.content_columns %>
          <td><%=h programme.send(column.name) %></td>
        <% end %>
      </tr>
    <% end %>
  </table>
  <%= link_to ‘Previous page’, { :page => @programme_pages.current.previous } if @programme_pages.current.previous %>
  <%= link_to ‘Next page’, { :page => @programme_pages.current.next } if @programme_pages.current.next %><br />
  <%= link_to ‘Import XML’, :action => ‘load_xml’ %>

and add a new “load_xml.rhtml” template

<h1>Load XML<h1>
<%= form_tag({ :action=> ‘import_xml’}, {multipart => true }) %>
<%= file_field :document, :file %>
<%= submit_tag ‘Import’ %>
<%= end_form_tag ‘Import’ %>
<%= link_to ‘Back’, :action => ‘list’ %>

Ok.So much for the easy part. We need to add an entry to the controllerfor the ‘import_xml’ action that has just been declared. This will haveaccess to the embedded file uploaded using the file_field :document,:file instruction.

The decision to make the database table columns have exactly the same namesas the XML attributes allows for the following code to populate thedatabase. So the final app/controller/admin_controller.rb looks like:

class AdminController << ApplicationControllerscaffold :programme
  def import_xml
    require ‘rexml/document’
    file=params[:document][:file]
    doc=REXML::Document.new(file.read)
    doc.root.each_element(’//programme’) do |p|
      if not Programme.find(:first, :conditions => [ “name=?”, p.attibutes[:name] ]) then
        @programme=Programme.new
        @programme.update_attributes(p.attributes)
      end
    end
    redirect_to :action => ‘list’
  end
end

Ok. That’s it for now. I’ve scratched the rails surface and learnt something new. More discoveries soon.