Question

Second week on RoR (with no programming background). And I have a bit of an issue, I’m doing a Metacritic type of a website. And there are going to be ratings everywhere. I decided on 0 to 33 = red 34 to 66 = orange 67 to 100 = green which looks like that

index (controller:show)

 <td><% if show.reviews.count == 0 %>0
    <% elsif show.reviews.average("rating").between?(33, 66) %>
    <table class="orange">
      <tr>
        <td><b><%= number_with_precision(show.reviews.average("rating"), :precision => 0) %></b></td>
     </tr>
    </table>
    <% elsif show.reviews.average("rating").between?(66, 100) %>
    <table class="green">
      <tr>
        <td><%= number_with_precision(show.reviews.average("rating"), :precision => 0) %></td>
      </tr>
    </table>
    <% elsif show.reviews.average("rating").between?(00, 33) %>
    <table class="red">
      <tr>
        <td><%= number_with_precision(show.reviews.average("rating"), :precision => 0) %></td>
      </tr>
    </table>
    <% end %>
  </td>

My issue is that I’m gonna need to repeat that code, a lot, see (I’m only getting started:
show (controller show)

<p>
  Note: <% if @ratings == 0 %>0
  <% elsif @ratings.between?(33, 66) %>
  <table class="orange">
    <tr>
      <td><b><%= number_with_precision(@ratings, :precision => 0) %></b></td>
    </tr>
  </table>
  <% elsif @ratings.between?(66, 100) %>
  <table class="green">
    <tr>
      <td><%= number_with_precision(@ratings, :precision => 0) %></td>
    </tr>
  </table>
  <% elsif @ratings.between?(00, 33) %>
  <table class="red">
    <tr>
      <td><%= number_with_precision(@ratings, :precision => 0) %></td>
    </tr>
  </table>
  <% end %>
</p>

Somebody told me this should be a model but I don’t really know how to write it. Any help ?

Answer 1

First of all you should add an instance method to your Show model that retrieves and caches the average rating for a show. This prevents querying the database multiple times for the same data:

def average_rating
  @average_rating ||= self.reviews.average('rating')
end

The code that returns the appropriate css class for a Show can go into a helper (e.g. the ShowHelper):

module ShowHelper
  def average_rating_class_for(show)
    if show.average_rating < 34
      'red'
    elsif show.average_rating > 66
      'green'
    else
      'orange'
    end
  end
end

With this, your views become much cleaner:

<td>
<% if show.reviews.count == 0 %>
  0
<% else %>
  <table class="<%= average_rating_class_for(show) %>">
    <tr>
      <td><%= number_with_precision(show.average_rating, :precision => 0) %></td>
    </tr>
  </table>
<% end %>
</td>

And:

<p>
  Note:
<% if @show.reviews.count == 0 %>
  0
<% else %>
  <table class="<%= average_rating_class_for(@show) %>">
    <tr>
      <td><%= number_with_precision(@show.average_rating, :precision => 0) %></td>
    </tr>
  </table>
<% end %>
</p>

You could even move the generation of the entire table into a model. (Although you shouldn’t be using a table here, but that’s a different matter.)

module ShowHelper
  def average_rating_class_for(show)
    if show.average_rating < 34
      'red'
    elsif show.average_rating > 66
      'green'
    else
      'orange'
    end
  end

  def average_rating_table_for(show)
    if show.reviews.count == 0
      '0'
    else
      content_tag :table do
        content_tag :tr do
          contect_tag :td, :class => average_rating_class_for(show) do
            number_with_precision(show.average_rating, :precision => 0)
          end
        end
      end
    end
  end
end

With this you view becomes:

<td>
  <%= average_rating_table_for(show) %>
</td>

What Andre suggests is possible too, but it may be a bit difficult to comprehend for a beginner like yourself. This is simpler.