Question

I am new to coding – and have not enough reputation to comment this answer:
Rails 3: Uniqueness validation for nested fields_for

So I am creating this question as "Part 2" 🙂

I am a web designer but curious to learn coding, held with this from my days.

# app/validators/nested_attributes_uniqueness_validator.rb   
class NestedAttributesUniquenessValidator < ActiveModel::EachValidator
        record.errors[attribute] << "Products names must be unique" unless value.map(&:name).uniq.size == value.size
      end
end

above code with "ActiveModel::EachValidator" throw this error:

"undefined method `map’ for "Area 1":String"

---

# app/validators/nested_attributes_uniqueness_validator.rb   
class NestedAttributesUniquenessValidator < ActiveModel::Validator
    record.errors[attribute] << "Products names must be unique" unless value.map(&:name).uniq.size == value.size
  end
end

above code with "ActiveModel::Validator" throw this error:

"Subclasses must implement a validate(record) method. "

---

this is model file:

class Area < ActiveRecord::Base


  validates :name,
            :presence => true,
            :uniqueness => {:scope => :city_id},
            :nested_attributes_uniqueness => {:field => :name}

  belongs_to :city

end

---

You can find complete code over here:
https://github.com/syed-haroon/rose

Answer 1

I found the answer over here :

https://rails.lighthouseapp.com/projects/8994/tickets/2160-nested_attributes-validates_uniqueness_of-fails

&

validates_uniqueness_of in destroyed nested model rails

This is for rails 2, one line need to me modified over here:
add_to_base has been deprecated and is unavailable in 3.1. Use self.errors.add(:base, message)