Question

I’m developing an event calendar, where each hour is a slot that allows users to sign one appointment.

Since there is a feature that allows users to update the slot (and also change date/time) I’d like to perform some check before to update the value, making sure that the slot is free.
So I ended up with a method like this:

if Event.find(:all, :conditions => ["start_at = ? AND event_calendar_id = ?", self.start_at, self.id])
  errors.add :base, "You cannot save this appointment in that slot."
  return false
end

By the way it creates issues when updating other fields without changing the datetime field, because it finds itself and raises the exception making impossible to update it.

Is there a way I can access database data such as the current id so I can filter out itself from the values, or check if the submitted datetime field is equal to the database one (so i can skip this check).

What’s the best way to do this?
Thanks.

P.S. I’m using rails 3.2.3

Answer 1

To exclude self from the results just add a condition to your where excluding its id. Also save some memory and processor time by calling exists?, which just returns true or false instead of fetching an entire row and building a new object:

Event.where( :start_at => start_at,
             :event_calendar_id => event_calendar.id ).
      where( "id <> ?", id ).
      exists?