Ruby on Rails

def import
   @question = Question.new    ## You have just created a new instance of model class Question
   @question.import(params[:file])
      redirect_to root_url, notice: "Questions imported succefully."
  end

class Question
validates :id, uniqueness: true   ## see below
def self.import(file) 
CSV.foreach(file.path, headers: true) do |row|    ## okay so you will iterate by row
question_hash = row.to_hash          
                        ## This is okay, but you should put a watch on row, and understand its structure.  In doing so, you may not need to convert row to row.to_hash.  Otherwise, you should put a watch on row.to_hash to verify that the
                        ## structure of the 'row' is consistent with your database structure  and other matters that may be in your Question model
                        ##@question = Question.where(id: question_hash["id"]) 
                        ## okay this seems reasonable  but at the model level rather than creating a new Question object, you should rather be doing validation on id, see above.
                        ##  If I were you I would do validation on the record, not just the id
    ## if @question.count == 1
    ##@question.first.update_attributes(question_hash)   ## self not new instance of Question
@return_value_on_update_attributes = self.update_attributes(question_hash)     ## Read: http://apidock.com/rails/ActiveRecord/Base/update_attributes
unless @return_value_on_update_attributes  ## unless @return_value_on_update_attributes is false, eg, if not true
    puts "There was an error in record " +     question_hash["id"]
    puts self.errors.to_yaml      ## This way you can continue, and then later you need to check for errors.  Of course there are other ways to manage and learn errors.  But for now...
end  # end unless
end  # end foreach

end # end self.import(file)