query in rails3 - ruby

Question

In another question that i asked recently i got a really good answer and the code worked... But i do not know exactly why it works... Now i have a similar problem, but don't know how to solve it...?
What i have:
Models
users
questions (with answer_id)
answers
votes (with answer_id and user_id)
model for users:
has_many :questions
has_many :votes
def can_vote_on? (question)
!question.answers.joins(:votes).where('votes.user_id = ?', id).exists?
end
def voted_answer? (question)
(what to do here...?)
end
model for questions:
belongs_to :user
has_many :answers, :dependent => :destroy
accepts_nested_attributes_for :answers, :reject_if => lambda { |a| a[:text].blank? }, :allow_destroy => true
model for answers:
belongs_to :question
has_many :users, :through => :votes, :dependent => :destroy
has_many :votes
model for votes:
belongs_to :answer
belongs_to :user
In my question view i want to make a text bold when the current_used has voted on that specific answer. So how do i finish this:
<% for answer in #question.answers %>
<% if current_user.voted_answer? (#question) %>
<td>
<strong><%= answer.text %></strong>
</td>
<% else %>
<td>
<%= answer.text %>
</td>
<% end %>
<% end %>
Thijs

Answer 1

you may do this
<% for answer in #question.answers %>
<% if answer.votes.index{|vote| vote.user_id == current_user.id} %>
<td>
<strong><%= answer.text %></strong>
</td>
<% else %>
<td>
<%= answer.text %>
</td>
<% end %>
<% end %>
UPDATE
more logical variant create voted_by_user? function in class Answer
class Answer
def voted_by_user?(user)
voits.where('votes.user_id = ?', user.id).exists?
end
end
<% #question.answers.each do |answer| %>
<td>
<% if answer.voted_by_user?(current_user) %>
<strong><%= answer.text %></strong>
<% else %>
<%= answer.text %>
<% end %>
</td>
<% end %>

Answer 2

It sounds like you just want the opposite result of can_vote_on?, i.e. if a user cannot vote on an answer (can_vote_on? returns false), then it means that they already voted (voted_answer? should return true in this case) and vice versa.
One way to solve this is to have voted_answer? return the negation of can_vote_on:
def voted_answer? (question)
!can_vote_on? question
end
Or of course you could use the query you used in can_vote_on? without the negation:
def voted_answer? (question)
question.answers.joins(:votes).where('votes.user_id = ?', id).exists?
end
But I would prefer the first solution due to the DRY principle.
UPDATE
I was wrong about the negation. In this case you're dealing with a specific answer, not all of them.
In your model you'll want the following:
def voted_answer? (answer)
answer.votes.where('votes.user_id = ?', id).exists?
end