DRY validates_format_of?

Rails
1

In a model I have following validates_format_of. Is there an easy way to
DRY this up? It seems to be rather repetitive.

validates_format_of :expiration_date, :with =>
/^[0-9]{4}[-][0-9]{2}[-][0-9]{2}$/
validates_format_of :activation_date, :with =>
/^[0-9]{4}[-][0-9]{2}[-][0-9]{2}$/
validates_format_of :some_other_date, :with =>
/^[0-9]{4}[-][0-9]{2}[-][0-9]{2}$/
…

Thanks

2

Hi Jens,

validates_format_of takes a regular expression as its argument:

with - The regular expression used to validate the format with (note: must be supplied!)

… so you just assign the regular expression to a variable

date_format = /^[0-9]{4}[-][0-9]{2}[-][0-9]{2}$/

… and use it in your validates_format_of calls as follows:

validates_format_of :expiration_date, :with => date_format
validates_format_of :activation_date, :with => date_format
validates_format_of :some_other_date, :with => date_format

Here’s how that works:

~ $ irb

date_format = /^[0-9]{4}[-][0-9]{2}[-][0-9]{2}$/
=> /^[0-9]{4}[-][0-9]{2}[-][0-9]{2}$/

date_format.class
=> Regexp

/^[0-9]{4}[-][0-9]{2}[-][0-9]{2}$/.class
=> Regexp

exit
~ $ _

Peter

3

Sigh! … so easy!

Thanks Peter for your time

4

Hi Jens,

validates_format_of takes a regular expression as its argument:

• with - The regular expression used to validate the format with
(note: must be supplied!)

… so you just assign the regular expression to a variable

date_format = /^[0-9]{4}[-][0-9]{2}[-][0-9]{2}$/

… and use it in your validates_format_of calls as follows:

validates_format_of :expiration_date, :with => date_format
validates_format_of :activation_date, :with => date_format
validates_format_of :some_other_date, :with => date_format

Note that class of the regexp:

~ $ irb

date_format = /^[0-9]{4}[-][0-9]{2}[-][0-9]{2}$/
=> /^[0-9]{4}[-][0-9]{2}[-][0-9]{2}$/

date_format.class
=> Regexp

/^[0-9]{4}[-][0-9]{2}[-][0-9]{2}$/.class
=> Regexp

exit
~ $

DRY is the future :slight_smile:

Peter

5

On Jun 7, 2008, at 7:59 AM, Jens – wrote:

/^[0-9]{4}[-][0-9]{2}[-][0-9]{2}$/
…

I wrote a series of custom validations that in addition to defining a
number of common character patterns as named validations, it also
allowed multiple fields per validation

http://www.railsdev.ws/blog/11/custom-validations-in-rails/

It made a huge difference in DRYness and the amount of code needed
for validations.

–
def gw
writes_at ‘www.railsdev.ws’
end