```ruby
module Carto
  # Rails 3 stores nil strings with JSON serialization as 'null', so we need to replace it with a valid value.
  # See https://github.com/rails/rails/issues/13144
  class CartoJsonSerializer
    def self.dump(hash)
      hash.nil? ? nil : hash.to_json
    end

    def self.load(value)
      value.nil? ? nil : hash(value).with_indifferent_access
    end

    def self.hash(value)
      value.is_a?(Hash) ? value : JSON.parse(value)
    end
  end

  # CartoJsonSerializer is closer to Rails Json serializer, using with_indifferent_access
  # for load. The problem with that is that although you can _access_ first
  # level keys both with symbols and keys, other common operations, such as
  # key comparison, fail, and it only applies to the first level.
  class CartoJsonSymbolizerSerializer < CartoJsonSerializer
    def self.load(value)
      value.nil? ? nil : hash(value).deep_symbolize_keys
    end
  end
end

class CartoJsonSymbolizerValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value)
    record.errors[attribute] << 'wrongly formatted (not a Hash or invalid JSON)' if value && !value.is_a?(Hash)
  end
end
```

Support array JSONs in CartoJsonSerializer
user
```ruby
module Carto
  # Rails 3 stores nil strings with JSON serialization as 'null', so we need to replace it with a valid value.
  # See https://github.com/rails/rails/issues/13144
  class CartoJsonSerializer
    def self.dump(hash)
      hash.nil? ? nil : hash.to_json
    end

    def self.load(value)
      if value
        h = hash(value)
        h.is_a?(Hash) ? h.with_indifferent_access : h
      end
    end

    def self.hash(value)
      value.is_a?(Hash) || value.is_a?(Array) ? value : JSON.parse(value)
    end
  end

  # CartoJsonSerializer is closer to Rails Json serializer, using with_indifferent_access
  # for load. The problem with that is that although you can _access_ first
  # level keys both with symbols and keys, other common operations, such as
  # key comparison, fail, and it only applies to the first level.
  class CartoJsonSymbolizerSerializer < CartoJsonSerializer
    def self.load(value)
      value.nil? ? nil : hash(value).deep_symbolize_keys
    end
  end
end

class CartoJsonSymbolizerValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value)
    record.errors[attribute] << 'wrongly formatted (not a Hash or invalid JSON)' if value && !value.is_a?(Hash)
  end
end
```
assistant