method

validates_presence_of

v1.1.6 - Show latest stable - 0 notes - Class: ActiveRecord::Validations::ClassMethods

validates_presence_of(*attr_names) public

Validates that the specified attributes are not blank (as defined by Object#blank?). Happens by default on save. Example:

  class Person < ActiveRecord::Base
    validates_presence_of :first_name
  end

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

Configuration options:

message - A custom error message (default is: "can’t be blank")
on - Specifies when this validation is active (default is :save, other options :create, :update)
if - Specifies a method, proc or string to call to determine if the validation should

occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }). The method, proc or string should return or evaluate to a true or false value.

Warning

Validate the presence of the foreign key, not the instance variable itself. Do this:

 validate_presence_of :invoice_id

Not this:

 validate_presence_of :invoice

If you validate the presence of the associated object, you will get failures on saves when both the parent object and the child object are new.

Show source

# File activerecord/lib/active_record/validations.rb, line 396
      def validates_presence_of(*attr_names)
        configuration = { :message => ActiveRecord::Errors.default_error_messages[:blank], :on => :save }
        configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)

        # can't use validates_each here, because it cannot cope with nonexistent attributes,
        # while errors.add_on_empty can
        attr_names.each do |attr_name|
          send(validation_method(configuration[:on])) do |record|
            unless configuration[:if] and not evaluate_condition(configuration[:if], record)
              record.errors.add_on_blank(attr_name,configuration[:message])
            end
          end
        end
      end

validates_presence_of

Related methods

Warning