module ActiveModel::Validations::HelperMethods

See ActiveModel::Validations::ClassMethods#validates for more information.
+:if+, +:unless+, +:on+, +:allow_nil+, +:allow_blank+, and +:strict+.
There is also a list of default options supported by every validator:

* :message - A custom error message (default is: "can't be blank").
Configuration options:

false.blank? # => true.
This is due to the way Object#blank? handles boolean values:

validates_inclusion_of :field_name, in: [true, false].
values are +true+ and +false+), you will want to use
If you want to validate the presence of a boolean field (where the real

The first_name attribute must be in the object and it cannot be blank.

end
validates_presence_of :first_name
class Person < ActiveRecord::Base

Object#blank?).
Validates that the specified attributes are not blank (as defined by

def validates_presence_of(*attr_names)
  validates_with PresenceValidator, _merge_attributes(attr_names)
end