Check the length of an attribute if present

Question

How do I validate when the presence of a model attribute is optional, but if present, the length of the attribute must be more than three characters?

+3

ruby-on-rails activerecord ruby-on-rails-4 ruby-on-rails-4.2 rails-activerecord

Alek Apr 26. 15 at 15:48

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1 answer

potashin · Accepted Answer · 2015-04-26T15:52:34+0000

You can allow the attribute to be empty with allow_blank: true

or nil

with allow_nil: true

, and also check length:

:

validates :attr, length: {minimum: 4}, allow_blank: true
validates :attr, length: {minimum: 4}, allow_nil: true

You can also use if:

or unless:

:

validates :attr, length: {minimum: 4}, unless: -> (o) do o.blank? end