模型 Child、Ruby on Rails 中父级的验证值

Question

I'm trying to ask the started_on value of parent in child_model. I want to compare, if it has the same period

assumed, I have these two classes

class Parent < ActiveRecord::Base
  has_many :children
end

And this class, Child_Class:

class Child < ActiveRecord::Base
  belongs_to :parent
  validates :name, presence: true, :length => { :minimum => 2, :maximum => 50 }
  validates :finished_on, presence: true, date: {not_equal: :started_on}
  validates :started_on, presence: true, date: {after: :parent.started_on}
end

What I need is the started_on value of parent

:parent.started_on returns me

undefined method 'started_on' for :project:Symbol

And I'm using this validators for my date Validators Thanks

Answer 1

You want to use it without a symbol.

ie

parent.started_on

As outlined in the guides

Answer 2

class Child < ActiveRecord::Base
  belongs_to :parent
  validates :name, presence: true, :length => { :minimum => 2, :maximum => 50 }
  validates :finished_on, presence: true, date: {not_equal: :started_on}
  validate :validate_started_on

  private

  def validate_started_on
    return if parent.nil?
    return if started_on > parent.started_on
    errors.add :started_on, :should_be_after_the_parent_started_on 
  end
end