validates_presence_of

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

class Person < ActiveRecord::Base
  validates_presence_of :first_name
end

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

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

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

Configuration options:

• :message - A custom error message (default is: “can’t be blank”).

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