Rails/ActiveModel passing arguments to EachValidator

Question

I have a very generic validator and I want to pass it arguments.

Here is an example model:

class User
  include Mongoid::Document

  field :order_type
  has_many :orders, inverse_of :user
  validates: orders, generic: true #i want to pass argument (order_type)

  field :task_type
  has_many :tasks, inverse_of :user
  validates: tasks, generic: true #i want to pass argument (task_type)
end

and Example validator:

class GenericValidator < ActiveModel::EachValidator
  def validate_each(object, attribute, value)
    if some_validation?(object)
      object.errors[attribute] << (options[:message] || "is not formatted properly") 
    end
  end
end

Is there any way to pass arguments to the validator dependant on which field it is validating?

thanks

Anders

What are you trying to achieve by doing this? This doesn't strike me as the best way to do this given the Rails API. – Pancreatotomy

In my original code I want to find if there is a cyclic dependency in my model. ModelA has many Model B. Model B has one Model A. I want to validate there is no cycle from Model A back to itself. The thing is, I have two different relations which need to validate cycles and there is a very minimal difference in the validator between them. I wanted to see if I could do it generically passing which fields to search for cycles as opposed to rewriting the same cycle logic and validator. – Anders

I think you may be better off using subclassing for that instead of parameterization. – Pancreatotomy

I am using subclasses for now however I'm still interested if parameters can be passed through validators. There are other places in my code I can use this ability and I'm just curious – Anders

Answer 1

I wasn't aware of this either, but if you want to pass an argument, then pass a hash to generic: instead of true. This post details the exact process you're wanting to follow:

class User
  include Mongoid::Document

  field :order_type
  has_many :orders, inverse_of :user
  validates: orders, generic: { :order_type => order_type }

  field :task_type
  has_many :tasks, inverse_of :user
  validates: tasks, generic: { :task_type => task_type }
end

GenericValidator should now have access to both arguments you're wanting to pass in validation: options[:order_type] and options[:task_type].

It might make more sense, however, to divide these up into two validators, with both inheriting the shared behavior as mentioned by dpassage:

  class User
    include Mongoid::Document

    field :order_type
    has_many :orders, inverse_of :user
    validates: orders, order: { type: order_type }

    field :task_type
    has_many :tasks, inverse_of :user
    validates: tasks, task: { type: task_type }
  end

Juvenal