[Rails] bug in postgresql 'now' time handling??

[Ara.T.Howard]

On Fri, 4 Mar 2005, Dave Steinberg wrote:

> What if there was a way to supply 'Time.now' to the ruby world and the
> string 'now' to the database (covering the unsaved object case).  Then if we
> reload newly saved objects, we'd be completely in sync.

that'd be pretty easy:

   def default_values value
     ...
       when /now/
         now = Time::now
         class << now
           def bi_polar_to_s
             'now'
           end
         end
         now
     ...
   end

...

   def rails_obj_to_rdbms_mapping value
     meth =
         if value.respond_to? 'bi_polar_to_s'
           'bi_polar_to_s'
         ...
         ...
     value.send meth
   end

so conceptually mark objects that that need this split to_s functionality -
one to_s in rails-land and another in db-land.  i don't know where the second
half takes place or my example might make more sense but maybe it's clear
enough?

> While reading through the docs yesterday, I literally laughed out loud at
> the last one.  We could provide some ruby-equivelant constants for most of
> those, obviously the tricky ones are now, and +/- infinity.  For the others,
> a patch would be easy.

to really handle +/- infinity i think you need to extend the built in time
class to be able to handle two special singleton objects with appropriate
comparisson semantics (alwasy less/greater than every other time except
themselves) AND a special string representation - maybe

   '0000-00-00 00:00:00-00'

and

   '9999-99-99 99:99:99-99'

since these are practically impossible...  everytime i've tackled this before
i've given up though.  time can be so tricky to manage (no pun intended).

> Agreed.  When I came to the code, they weren't there, and I wasn't familiar
> with them, so I just handled 'now' as best I could.  I think they come back
> as strings more for accidental reasons than intentional ones.

fair enough.

> Any ideas how we could handle this gracefully?  In my own code I've dealt
> with the inability of ruby's Time object to just specify a time without a
> date, so if we've got several problems with this object, perhaps we look
> towards supplying a more full-featured one.  Ideas?

maybe a TimeStamp object?  this might be a really clean solution - but a bit
of work and thinking...

>> at this point in half-agreement with Dave Lee; i don't think 'now' should
>> come back as a string - rather it should come back as a string like the
>> rest of of the special time values.  this is the simplest solution that is
>> totally correct IMHO.
>
> Yes, but the least sublime.  At the very least, we should recognize the
> other special keywords and provide Time object equivalents for them and
> return the others as strings.  If we do return 'now' as a string, we ought
> to update the helpers so that they can deal with it.

i agree that it would be nice to give something other than a string and now
agreed that it's o.k. to have approximations at the presentation (rails-to_s)
level - so long as the db stays consistent in the end.  this is a 'wiki-able'
oddity most people should be able to grasp...

> Few seem to be chiming in.  I'll try and post a patch with the easy keywords
> properly adjusted, and I'll try and play around with a split representation
> for now.

o.k. then - i really need to read some more source before i can suggest any
objectification of the problem.  i've got to do some rails stuff this weekend
so i'll poke around then and mull some more.

cheers.

-a
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