Improved "treat 0000-00-00 00:00:00 as nil Date"

[kirillrdy]

It is not right to assume that if year is 0 then date is nil.
In our example we store dates in BC and 0000-01-01 is a valid date

So I've added check that for date to be nil year month and mday have to be 0.

I couldnt find a test for this case and wasnt sure where is a good place to add it.

Cheers,
Kirill R

[martinotten]

'"Year zero" does not exist in the widely used Gregorian calendar or in its predecessor, the Julian calendar. Under those systems, the year 1 BC is followed by AD 1.' http://en.wikipedia.org/wiki/0_(year)

Are you sure that 0000-01-01 is a valid date in BC?

[kirillrdy]

Sorry, i should explain.

year 0000 is 1 BC
Postgres supports BC dates , as in it actually stores it as "0001-01-01 BC" which when queried as a date returns 0000-01-01, which then rails makes nil

hope it makes sence.

[kirillrdy]

sorry one more thing
when you save Date.new(-1000,1,1) to rails Postgres stores it as "1001-01-01 BC"
It does conversion based on fact that year 0 doesnt exist. so first year before 1 AD is 1 BC, hence year 0 is 1 BC

[NZKoz]

Seems fine to me, Date.new(0,0,0) raises ArgumentError: invalid date but Date.new(0,1,1) returns a date.

I'm not sure that Date and DateTime will do sensible things with BC dates, but seems harmless enough to support the values if the database returns them.