Question

Could you tell me if there is a better way.

Models:

class Skill
  has_many :tags
  has_many :positions
end


class Tag
  belongs_to :skill
  has_and_belongs_to_many :positions
end


class Position
  belongs_to :skill
  has_and_belongs_to_many :tags
end

I want to list all skills and the tags of their positions. Like this:

skill - tag tag tag tag
skill - tag tag
...

I managed to acheive it like this:

<% @skills.each do |skill| %>
  <%= skill.name %>   
  <% skill.positions.collect{|p| p.tags}.flatten.uniq.each do |t| %>
    <%= t.name %>
  <% end %>   
<% end %>

And my skills_controller:

def index
  @skills = Skill.all
end

Is this the right way?

Answer 1

Since tagging is a pretty common problem I’d recommend taking a look at acts-as-taggable-on, a widely used and very good gem for adding tags to any Rails model.

Regardless, your models look pretty good (except that has_and_belongs_to_many is often eschewed in favor for has_many :through), but I do see room for improvement here:

<% skill.positions.collect{|p| p.tags}.flatten.uniq.each do |t| %>
  <%= t.name %>
<% end %>  

Firstly, this is a lot of business logic to put in your view. You should do this in your controller instead. Secondly, it would be more performant to do it the other way around:

@tags = Tag.all :conditions => [ "tag.id IN (?)", skill.positions.map &:id ]

There are more efficient ways still to do this, but this ought to give you an idea.