Access parent through child in view using rails - ruby-on-rails

Question

I have a model Field with children Topics. Topics are given to posts and I want to display the Fields which topics are children of (e.g If a post has the topics 'rofl', 'lol' and 'lmao' and all of these topics belonged to the parent 'Internet abbreviations').
I want to display something like this:
INTERNET ABBREVIATION rofl lol lmao
Here is the code from the view.
<div class="fields">
<% reading.topics.each do |topic| %>
<span class="indivfields">
<%= link_to topic.field.name, field_path(topic.field) %>
</span>
</div>
<div class="subjects">
<% reading.topics.each do |topic| %>
<span class="indivsubjects"> <%= link_to topic.name,field_topic_path(topic.field,topic) %></span>
<% end %>
</div>
<% end %>
The problem is because the first reading.topic.each do is topic and not field so, continuing the example above, the output I end up with is this:
INTERNET ABBREVIATION rofl lol lmao
INTERNET ABBREVIATION rofl lol lmao
INTERNET ABBREVIATION rofl lol lmao
It prints based on the number of children and I want this to display once. Thanks!

Answer 1

Reading has_many field has_many topics it seems. I would structure the models like this:
class Reading
has_many :fields
has_many :topics
end
class Field
belongs_to :reading
has_many :topics
end
class Topic
belongs_to :reading
belongs_to :field
end
That way you can do reading.fields.each:
<%= reading.fields.each do |field| %>
<h1><%= field %>
<%= field.topics.each do |topic| %>
<p><%= topic %></p>
Why? Because you want to have your software to map the domain model (or how things are in the real world) as much as possible. It just seems intuitive, even from an outsider perspective, that a post have the option to be categorized by Field and Topic.
For our application we do the same thing. We have Questions, which have Subjects and Topics, and Topics belong to Subject. Same database schema as the one I have above (just different names).
However if that didn't make sense (hehe) the other ways to solve this are to do a group to move up the models from Topic to Field. Involves SQL (check this out: http://guides.rubyonrails.org/active_record_querying.html#group), and grouping via a hash (Group Hash by values in ruby). Sorry if I am not as helpful as I can, I am a bit tired now.
By the way I suggest don't do random abbreviations like indiv. I know it is in your best intention, and it sounds intuitive to abbreviate individual to indiv, but it's just best coding practice to not have random abbreviations, maybe someone else will join you in the coding and they might think about what indiv is. (I don't have the article to Clean Code but check this out: http://agileinaflash.blogspot.com/2009/07/abbreviations.html)

Answer 2

So I have an answer for you all. One of my classes is still poorly named using the 'indiv' abbreviation so please forgive me for that. I needed to use the group_by method. Here is the code:
<% reading.topics.group_by(&:field).each do |fields, topics| %>
<%= link_to fields.name, field_path(fields), class: "individualfields" %>
<div class="subjects">
<%= topics.collect { |t| link_to t.name, field_topic_path(fields, t), class: "indivsubjects" }.join.html_safe %>
</div>
<% end %>
And thats it. Thanks for getting to this answer must go to various people on the Rails IRC channel. It worked out very nicely because this code is actually smaller than my previous code for rending topics alone, and this renders fields and topics.