如何对已经具有多个验证的ActiveModel属性进行条件验证？

Question

I'm using Authlogic which by default puts a few validations(length, uniqueness, format, etc) on fields like login, email, and password.

I'd like to be able to skip all validations attached to one of the attributes if, say, another attribute is present.

Is this possible? Something like:

validate :email, :unless => :has_openid?

which will then skip the format, length, and uniqueness validations just on the email attribute.

I'm working with a Rails 3.1.x app and authlogic 3.1.0

Update: I was trying to follow this article, but I couldn't get it to work properly: http://erikonrails.snowedin.net/?p=242

Answer 1

The way I've done this with authlogic is by passing a block to acts_as_authentic :

acts_as_authentic do |config|
  with_options :unless => :has_openid? do      
    config.merge_validates_format_of_email_field_options
    config.merge_validates_length_of_email_field_options
    config.merge_validates_uniqueness_of_email_field_options
  end
end

Answer 2

I've written a workaround and abstracted it out into a gem: https://github.com/synth/conditional_attribute_validator

Gemfile:

gem 'conditional_attribute_validator', :git => "git://github.com/synth/conditional_attribute_validator.git"

Example:

class User
  include ConditionalAttributeValidator

  validate_attributes_with_condition :login, :password, :password_confirmation, :unless => :has_another_form_of_authentication?
end

Source:

def validate_attributes_with_condition(*args)
  opts = args.extract_options!
  raise "Must have an :if or :unless option" unless opts.has_key?(:if) or opts.has_key?(:unless)

  merge_methods = self.methods.grep(/merge_.*_options/)
  args.each do |field|
    merge_methods.grep(/#{Regexp.quote(field)}/).each do |m|
      self.send(m, opts)
    end
  end
end

Rails automagically creates the merge_ attr _options methods based upon whatever validations have been specified in order to merge options into an existing validation. So I lookup these methods and iterate over them and check if that method applies to a particular field. If so, I call the merge_ attr _options method and pass in the options.

I'm not too concerned about performance since this is just performed on initialization.