Differentiating between `blank` and `not_a_date` about date_validator

[dgmstuart]

Yup - I've been bitten by that one. The solution is to use

date: { allow_blank: true }

So the date validation won't get run if date is not present.

[mlt]

I have something like

  validates :effective_to, date: { allow_blank: true, after: :effective_from }

It complains if effective_to is blank :( ["Effective to is not a date"]

[dgmstuart]

@mlt Here's a section of code involved, which suggests that your code above should work:

date_validator/lib/active_model/validations/date_validator.rb

Lines 52 to 71 in 0a1f7ae

	def validate_each(record, attr_name, value)
	before_type_cast = :"#{attr_name}_before_type_cast"
	value_before_type_cast = if record.respond_to?(before_type_cast)
	record.send(before_type_cast)
	else
	nil
	end
	if value_before_type_cast.present? && value.nil?
	record.errors.add(attr_name, :not_a_date, options)
	return
	end
	return if (value.nil? && options[:allow_nil]) || (value.blank? && options[:allow_blank])
	unless value
	record.errors.add(attr_name, :not_a_date, options)
	return
	end

A blank string can be many things: nil, empty string, string containing only whitespace, false - which is it in your scenario?

[mlt]

My bad! I was messing around with parameter coercion substitution that I want to treat blank as infinite. This fragment indeed does work! However, there is another problem. It doesn't respect DateTime::Infinity that was coming from my strong params filter. I forgot I added

      p[:effective_to] = DateTime::Infinity if p.fetch(:effective_to, '').blank?

Note, that

validates :effective_to, date: { after: :effective_from }, unless: Proc.new{ |p| p.effective_to.blank? }

worked fine with blank (actually infinite) parameter. It seems to me they should be equivalent.