Rails - Nov 2005 - Issues with date validation.

I''ve had a bunch of issues with date validation and am starting to
wonder
whether I''m missing the easy way to deal with them. Let''s say
I have an
employees table with some date fields in it. I would like to do validation
like this:

class Employee < ActiveRecord::Base
	validates_presence_of :hire_date, :departure_date
	validates_date :hire_date, :departure_date
end

The first thing I realized was that there is no validates_date method. So I
wrote one (it didn''t work):

def validates_date(*attr_names)
	configuration = { :message => ''invalid date'' }
	configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)
	validates_each(attr_names,configuration) do |record, attr_name, value|
		begin
	            Date.parse(value.to_s)
		rescue ArgumentError
			record.errors.add(attr_name, configuration[:message])
		end
	end
end
	
The problem here is that any timestamp attribute gets typecast to a Time
object and if that parsing fails, the error is silently ignored and the value
for that attribute becomes nil. By the time we get to my validation method,
the value is nil, so you can''t parse it. So instead of using
''value'' to
parse, I do this to get the value before the type cast:

value = record.send("#{attr_name}_before_type_cast")

This still leaves the problem with validates_presence_of which will give you
an error if the date is there but not valid. So I adjusted my validates_date
to take an optional argument ''nil_ok'' which lets you say
whether the date can
be blank or not.  So it is finally working like I want, but I think there may
be some fundamental problem in Rails of ignoring any errors that occur during
attribute typecasting.

What does everyone think?


Here''s the final validator code, just in case anyone is interested.

module ActiveRecord
  module Validations
    module ClassMethods
      def validates_date(*attr_names)
        configuration = { :message => ''invalid date'',
:nil_ok => true, :message_for_blank => "can''t be blank"
}
        configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)
        validates_each(attr_names,configuration) do |record, attr_name, value|
          begin
            value = record.send("#{attr_name}_before_type_cast")
            if value.strip == ''''
              if configuration.fetch(:nil_ok, true)
                next
              else
                record.errors.add(attr_name, configuration[:message_for_blank])
                next
              end
            end
            Date.parse(value.to_s)
          rescue ArgumentError
            record.errors.add(attr_name, configuration[:message])
          end
        end
      end
    end
  end
end

I was going to write something like that in a day or two. Will let you know
if I have any comments after using it.

-=- Neeraj

On 11/4/05, Peter Haight <peterh-a5ZtNvmu7UvQT0dZR+AlfA@public.gmane.org>
wrote:
>
>
> I''ve had a bunch of issues with date validation and am starting to
wonder
> whether I''m missing the easy way to deal with them. Let''s
say I have an
> employees table with some date fields in it. I would like to do validation
> like this:
>
> class Employee < ActiveRecord::Base
> validates_presence_of :hire_date, :departure_date
> validates_date :hire_date, :departure_date
> end
>
> The first thing I realized was that there is no validates_date method. So
> I
> wrote one (it didn''t work):
>
> def validates_date(*attr_names)
> configuration = { :message => ''invalid date'' }
> configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)
> validates_each(attr_names,configuration) do |record, attr_name, value|
> begin
> Date.parse(value.to_s)
> rescue ArgumentError
> record.errors.add(attr_name, configuration[:message])
> end
> end
> end
>
> The problem here is that any timestamp attribute gets typecast to a Time
> object and if that parsing fails, the error is silently ignored and the
> value
> for that attribute becomes nil. By the time we get to my validation
> method,
> the value is nil, so you can''t parse it. So instead of using
''value'' to
> parse, I do this to get the value before the type cast:
>
> value = record.send("#{attr_name}_before_type_cast")
>
> This still leaves the problem with validates_presence_of which will give
> you
> an error if the date is there but not valid. So I adjusted my
> validates_date
> to take an optional argument ''nil_ok'' which lets you say
whether the date
> can
> be blank or not. So it is finally working like I want, but I think there
> may
> be some fundamental problem in Rails of ignoring any errors that occur
> during
> attribute typecasting.
>
> What does everyone think?
>
>
> Here''s the final validator code, just in case anyone is
interested.
>
> module ActiveRecord
> module Validations
> module ClassMethods
> def validates_date(*attr_names)
> configuration = { :message => ''invalid date'', :nil_ok
=> true,
> :message_for_blank => "can''t be blank" }
> configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)
> validates_each(attr_names,configuration) do |record, attr_name, value|
> begin
> value = record.send("#{attr_name}_before_type_cast")
> if value.strip == ''''
> if configuration.fetch(:nil_ok, true)
> next
> else
> record.errors.add(attr_name, configuration[:message_for_blank])
> next
> end
> end
> Date.parse(value.to_s)
> rescue ArgumentError
> record.errors.add(attr_name, configuration[:message])
> end
> end
> end
> end
> end
> end
>
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>

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