I'm trying to create a Document instance with params passed from the post-submitted form:

My Mongo mapped document looks like:

class Good
  include MongoMapper::Document

  key :title, String
  key :cost, Float
  key :description, String
  timestamps!

  many :attributes

  validates_presence_of :title, :cost
end

And create action:

  def create
    @good = Good.new(params[:good])

    if @good.save
      redirect_to @good
    else
      render :new
    end
  end

params[:good] containes all valid document attributes - {"good"=>{"cost"=>"2.30", "title"=>"Test good", "description"=>"Test description"}}, but I've got a strange error from rails:

undefined method `keys' for ["title", "Test good"]:Array

My gem list:

*** LOCAL GEMS ***

actionmailer (2.3.8)
actionpack (2.3.8)
activerecord (2.3.8)
activeresource (2.3.8)
activesupport (2.3.8)
authlogic (2.1.4)
bson (1.0)
bson_ext (1.0)
compass (0.10.1)
default_value_for (0.1.0)
haml (3.0.6)
jnunemaker-validatable (1.8.4)
mongo (1.0)
mongo_ext (0.19.3)
mongo_mapper (0.7.6)
plucky (0.1.1)
rack (1.1.0)
rails (2.3.8)
rake (0.8.7)
rubygems-update (1.3.7)

Any suggestions how to fix this error?