Rails Pocket Reference

Validations

How many of us have had the experience of spending hours upon hours creating form validators, whether they are JavaScript or server-side validation. I know I have, and one of the reasons I love Rails: adding validation to your models is as easy as adding one line of code.

Here are the available validators that are useable by the models:

validates_acceptance_of(*attr_names)

Encapsulates the pattern of wanting to validate the acceptance of a Terms of Service checkbox (or similar agreement).

Example:

class Person < ActiveRecord::Base
  validates_acceptance_of :terms_of_service, :message =>
   "must be abided"
end

Options:

message

A custom error message (default is “must be accepted”).

on

Specifies when this validation is active (default is :save; other options are :create and :update).

accept

Specifies the value that is considered accepted. The default value is a string “1”, which makes it easy to relate to an HTML checkbox.

if

Specifies a method, proc, or string to call to determine if the validation should occur. The method, proc, or string should return or evaluate to a true or false value.

validates_associated(*attr_names)

Validates whether the associated object or objects are all valid themselves. Works with any kind of association:

Example:

class Book < ActiveRecord::Base
  has_many :pages
  belongs_to :library

  validates_associated :pages, :library
end

Options:

on

Specifies when this validation is active (default is :save; other options are :create and :update).

if

Specifies a method, proc, or string ...