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:

before validation.
a database column, since the attribute is typecast from "1" to +true+
checkbox. This should be set to, or include, +true+ if you are validating
an array ["1", true], which makes it easy to relate to an HTML
Also accepts an array of possible values. The default value is
* :accept - Specifies a value that is considered accepted.
accepted").
* :message - A custom error message (default is: "must be
Configuration options:

is not +nil+.
is entirely virtual. This check is performed only if +terms_of_service+
If the database column does not exist, the +terms_of_service+ attribute

end
validates_acceptance_of :eula, message: 'must be abided'
validates_acceptance_of :terms_of_service
class Person < ActiveRecord::Base

terms of service check box (or similar agreement).
Encapsulates the pattern of wanting to validate the acceptance of a

def validates_acceptance_of(*attr_names)
  validates_with AcceptanceValidator, _merge_attributes(attr_names)
end