Rails: Validating min and max length of a string but allowing it to be blank

Question

I have a field that I would like to validate. I want the field to be able to be left blank, but if a user is entering data I want it to be in a certain format. Currently I am us

Answer 1

You can also use this format:

validates :foo, length: {minimum: 5, maximum: 5}, allow_blank: true

Or since your min and max are the same, the following will also work:

validates :foo, length: {is: 5}, allow_blank: true

Answer 2

validates_length_of :reason, minimum: 3, maximum: 30

rspec for the same is

it { should validate_length_of(:reason).is_at_least(3).is_at_most(30) }

Answer 3

Or even more concise (with the new hash syntax), from the validates documentation:

validates :foo, length: 5..5, allow_blank: true

The upper limit should probably represent somehting more meaningful like "in: 5..20", but just answering the question to the letter.

Answer 4

From the validates_length_of documentation:

validates_length_of :phone, :in => 7..32, :allow_blank => true

:allow_blank - Attribute may be blank; skip validation.

Answer 5

How about that: validates_length_of :foo, is: 3, allow_blank: true

Answer 6

In your model e.g.

def validate
  errors.add_to_base 'error message' unless self.foo.length == 5 or self.foo.blanc?
end