Rails 3 validation in model failure

Question

I have a validate_completion method defined in my task.rb model. The Pseudo logic should be

if no hazards exist
  date_completed = Date.today
elsif any hazard exists with a risk_total > 1000
  date_completed = nil
else any hazard that exists has a risk_total =< 1000 
  date_complete = Date.today
end

The code looks like as follows.

    def validate_completion
if self.date_completed.nil?
  if self.Biohaz_exist == "No"
    if self.Hazmat_exist == "No"
      if self.Fire_exist == "No"
        if self.Hazengy_exist == "No"
          if self.Tool_exist == "No"
            if self.Rad_exist == "No"
              if self.Laz_exist == "No"
                if self.Mag_exist == "No"
                  if self.Ergo_exist == "No"
                    if self.Mechand_exist == "No"
                      if self.Road_exist == "No"
                        if self.Fall_exist == "No"
                          if self.Hazatm_exist == "No"
                            if self.Noise_exist == "No"
                              if self.Ovrhead_exist == "No"
                                if self.Cut_exist == "No"
                                  if self.Temp_exist == "No"
                                    if self.Access_exist == "No"
                                      if self.Cowrkr_exist == "No"
                                        if self.Lonewrkr_exist == "No"
                                          self.date_completed = Date.today
                                        elsif self.Biohaz_exist == "Yes" and self.Biohaz.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Hazmat_exist == "Yes" and self.Hazmat.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Fire_exist == "Yes" and self.Fire.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Hazengy_exist == "Yes" and self.Hazengy.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Tool_exist == "Yes" and self.Tool.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Rad_exist == "Yes" and self.Rad.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Laz_exist == "Yes" and self.Laz.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Mag_exist == "Yes" and self.Mag.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Ergo_exist == "Yes" and self.Ergo.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Mechand_exist == "Yes" and self.Ergo.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Road_exist == "Yes" and self.Ergo.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Fall_exist == "Yes" and self.Fall.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Hazatm_exist == "Yes" and self.Hazatm.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Noise_exist == "Yes" and self.Noise.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Ovrhead_exist == "Yes" and self.Ovrhead.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Cut_exist == "Yes" and self.Cut.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Temp_exist == "Yes" and self.Temp.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Access_exist == "Yes" and self.Access.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Cowrkr_exist == "Yes" and self.Cowrk.risk_total > 1000
                                          self.date_completed = nil
                                        elsif self.Lonewrkr_exist == "Yes" and self.Lonewrkr.risk_total > 1000
                                          self.date_completed = nil                                                                                  
                                        else
                                          self.date_completed = Date.today  
                                        end
                                      end
                                    end
                                  end
                                end
                              end
                            end
                          end
                        end
                      end
                    end
                  end
                end
              end
            end
          end
        end
      end
    end
  end
end

end

As is right now if no hazards exist, it successfully sets the date to today. And if I then add a hazard it effectively switches the date back to nil. However, If one hazard exists and it has a risk_total below 1000 the date remains nil.

Answer 1

"Well, given that your hazards are statically defined and not in the database, you could do something like this:

#definition of all the hazard
hazards = [:Fire, :Road, :Fall]
def validate_completion
  # find all the hazards that exist
  exists = hazards.select { |hazard| self.send("#{hazard.to_s}_exist") } 
  # find if at least one high risk hazard exists
  high_risk_total = exists.detect {|hazard| self.send("#{hazard.to_s}_risk_total") > 1000 }
  # find if at least one low rick hazard exists
  low_risk_total = exists.detect {|hazard| self.send("#{hazard.to_s}_risk_total") <= 1000 }

  # validation logic here
end

You can get by with this logic, but it might be significantly easier to make your hazards a database table and use ActiveRecord associations and queries to simplify this.