Yeah, I couldn't understand what Ken meant by his "state-machine" approach.
I can't think of a dry way of currently doing that.
I'm just not much concerned about this as I don't use AR and Sequel's
way of doing validation is by defining a "validate" method, so I'd put
my logic there, but anyway...
Em 21-06-2012 21:23, Anthony Richardson escreveu:
I can see some advantge of declaring a validation dependency. Checking
if an age is less than 16 makes no sense if the age has failed a
validation on being a number already.
maybe something like:
class User< AR::Base
validates_numericality_of :age
#custom validation
validate :user_older_16, :depends => :age
def user_older_16
errors.add(:age, "should be older 16") if age<= 16
end
end
Where :user_older_16 would only run if age has no errors. In the
context shown above this is a sensible dependency, but used
incorrectly the concerns expressed by others would be valid.
Another suggestion:
class User< AR::Base
validates_with_dependency do
validates_numericality_of :age
validate :user_older_16
end
def user_older_16
errors.add(:age, "should be older 16") if age<= 16
end
end
In the above the validations in the validate_with_dependency block
would execute in order, exiting the sequence if any fail.
I think the suggestion to have dependent validaiton is a good one as
it allows for structuring simiple validations where you know a
validation cannot possibly pass if an earlier one has failed.
Cheers,
Anthony Richardson.
On Thu, Jun 21, 2012 at 8:26 PM, Pavel Gabriel<[email protected]> wrote:
Hi!
I found that it's a popular use case for AR/AM validations:
class User< AR::Base
validates_numericality_of :age
#custom validation
validate :user_older_16
def user_older_16
errors.add(:age, "should be older 16") if age<= 16
end
end
When you will try to validate as the following:
user = User.new(age: 'bla')
user.valid?
you will get: ArgumentError: comparison of String with 16 failed.
Folks write a lot of code to check attribute values in their custom
validations, but it's not a DRY way because attributes already validated by
AM.
Is it a good idea to run validation methods only if errors.count == 0?
Or maybe we can add something like "validate_further :user_older_16" that
will run only if attributes are valid?
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