Question

I’m trying to create a new object that is related to two other models but I’m having a hard time getting it to work.

The model is:

vote.rb

class Vote < ActiveRecord::Base
  
  belongs_to :solution
  belongs_to :user
  
end

(The solution and user model both have has_many :votes on their side.

In my solutions controller I’m doing this:

  def process_vote
    solution = Solution.find(params[:id])
    vote = Vote.where(:user => current_user, :solution => solution)
    if(vote.count == 0)
      newvote = Vote.new
      newvote.user = current_user
      newvote.positive = true
      newvote.solution = solution
      newvote.save
    end
    respond_to do |format|
      format.js {
        render :nothing => true
      }
    end
  end

The query generated by ActiveRecord is looking for the wrong columns though, this is what console shows when I call the process_vote method:

   (0.6ms)  SELECT COUNT(*) FROM `votes` WHERE `votes`.`user` = 2 AND `votes`.`solution` = 5

Mysql2::Error: Unknown column 'votes.user' in 'where clause': SELECT COUNT(*) FROM `votes`  WHERE `votes`.`user` = 2 AND `votes`.`solution` = 5
Completed 500 Internal Server Error in 17ms

ActiveRecord::StatementInvalid (Mysql2::Error: Unknown column 'votes.user' in 'where clause': SELECT COUNT(*) FROM `votes`  WHERE `votes`.`user` = 2 AND `votes`.`solution` = 5):
  app/controllers/solutions_controller.rb:74:in `process_vote'

Any ideas what could be wrong? It seems to me that the relations are set up fine. The actual column names are user_id and solution_id.

Answer 1

1. Seems like you should not get full solution instance from the DB. Solution ID from params should be enough.
2. Do not use association names in the where. Use ID’s

So your action should looks like this:

def process_vote
  current_user.votes << Vote.new(:positive => true, solution_id => params[:id]) if current_user.votes.where(:solution_id => params[:id]).count == 0
  respond_to do |format|
    format.js {
      render :nothing => true
    }
  end
end