JBuilder extensions

class Jbuilder

  # don't repeat yourself. when WillPaginate
  def paginate!(collection, &block)
    if collection.respond_to?(:page)
      set! :total_entries, collection.total_entries
      set! :page, collection.current_page
      set! :per_page, collection.per_page
    else
      set! :total_entries, collection.count
      set! :page, 1
      set! :per_page, collection.count
    end
    set! :entries, collection, &block
  end

  # don't return null, should should be an empty string
  def _set_value(key, value)
    raise NullError, key if @attributes.nil?
    unless @ignore_nil && value.nil?
      if value.nil?
        @attributes[@key_formatter.format(key)] = ''
      else
        @attributes[@key_formatter.format(key)] = value
      end
    end
  end
  
  # when you want to skip a record when iterating over a collection
  def _map_collection(collection)
    return [] if collection.nil?

    collection.map do |element|
      _scope{ yield element }
    end.reject(&:blank?)
  end

end