How do you validate dates of models

i am wondering how you deal with date validation in your models … if i
have a date attribute it only eats date objects … so i when i do this

u = User.new(:born => Date.today)

it works, but this results in a nil value in :born attribute …

u = User.new(:born => ‘10.10.2007’)
puts(u.born) #results in nil

so now i cannot really validate dates because the string is not stored
in the attribute … whereas all other attributes store everything …
when i excpect a number in an attribute i can assign a string but the
object will stay invalid (if i have a validator)

so whats the best thing to deal with dates in connection with a web
form?

You need to pass it a Date object all the time. Something like
10-10-2007 or
10/10/2007 should work.

“but this results in a nil value in :born attribute …”

The above confused me. Did you do
u = User.new(:born => Date.today)
u.born

only for it to return nil?
On Dec 20, 2007 2:20 AM, Michal G. <
[email protected]> wrote:


Ryan B.
http://www.frozenplague.net

Michal G. wrote:

i am wondering how you deal with date validation in your models … if i
have a date attribute it only eats date objects … so i when i do this

u = User.new(:born => Date.today)

it works, but this results in a nil value in :born attribute …

u = User.new(:born => ‘10.10.2007’)
puts(u.born) #results in nil

so now i cannot really validate dates because the string is not stored
in the attribute … whereas all other attributes store everything …
when i excpect a number in an attribute i can assign a string but the
object will stay invalid (if i have a validator)

so whats the best thing to deal with dates in connection with a web
form?

I don’t think the dot notation works for dates. Hyphens and slashes are
okay though. In terms of validation, a simple trick I use is…

class User

validate :born_should_be_valid_date

protected

def born_should_be_valid_date
  born.to_date
rescue
  errors.add(:born, 'Invalid date for born')
end

end

The #to_date method is provided by Rails and will turn a string, Time or
Date object into a Date object if it can, and will raise an exception if
it can’t.

Hope that helps.

daniel i dont fully understand your approach … i still cannot assign

u = User.new(:born => ‘foo’)

here born will hold nil because it cannot be parsed to a date. but
normally it should keep the invalid value and indicate that the instance
is invalid …so the whole to_date stuff is not needed because i can
only assign a valid date anyway … if its not valid it sets the
attribute to nil

the thing is that i want to keep the value and show the user that the
value is invalid … like with all other attributes

hope you understand what i mean

On 12/20/07, Michal G. [email protected]
wrote:

the thing is that i want to keep the value and show the user that the
value is invalid … like with all other attributes

hope you understand what i mean

Mass assignment, methods like new and create (i.e. those which take a
hash of attribute names to variables appear to all nil out values
that dont match.

But if you instead did.

u = User.new
u.born = “foo” # or equivalently u[:born] = “foo”

you can get the string back with

u.born_before_type_cast


Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/

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