title: Rails - Getting an error message from the model that is not a Validation error
body: <p>So I have a method in a reservation model called add_equip.  This method does some checking to make sure the added piece of equipment is valid (not conflicting with another reservation).  </p>
  
  <p>The checks work.  If a added piece of equipment shouldn't be added it isn't, and if it should it is.  </p>
  
  <p>The problem is I can't figure out how to send the messages back up to the controller to be put in the flash message?  I know I must be missing something here, but I've googled for a few hours now and can't really find any clear explanations how how to pass errors back up the the controller, unless they are validation errors.</p>
  
  <p><strong>add_equip in reservations_controller</strong></p>
  
  <pre><code>    def add_equip
      @reservation = Reservation.find(params[:id])
      @addedEquip = Equip.find(params[:equip_id])
  
      respond_to do |format|
       if @reservation.add_equip(@addedEquip)
          flash[:notice] = "Equipment was added"
          format.html { redirect_to(edit_reservation_path(@reservation)) }
       else
          flash[:notice] = @reservation.errors
          format.html { redirect_to(edit_reservation_path(@reservation)) }
       end
      end
    end
  </code></pre>
  
  <p><strong>add_equip in reservation model</strong></p>
  
  <pre><code>def add_equip equip
     if self.reserved.find_by_equip_id(equip.id)
       self.errors.add_to_base("Equipment Already Added")
       return false
     elsif !equip.is_available?(self.start, self.end)
       self.errors.add_to_base("Equipment Already Reserved")
       return false
     else
       r = Reserved.new
       r.reservation = self
       r.equip = equip
       r.save
     end
    end
  </code></pre>
  
  <p>Any help would be greatly appreciated.  I know I'm missing something basic here.</p>