App Engine Jruby DataMapper 列表属性

Question

如何在 Google AppEngine 上的 Jruby 上的 DataMapper 中使用列表/数组作为属性？

Answer 1

这将像 has..and..belongs..to..many 一样工作，没有连接表...

class Person
  include DataMapper::Resource
  property :id,          Serial
  property :name,        String, :nullable => false
  property :project_ids, List
  timestamps :at
  # project should be flagged as archived, not deleted
  def projects
    Project.all(:id => project_ids)
  end
end

class Project
  include DataMapper::Resource
  property :id,          Serial
  property :name,        String, :nullable => false
  property :archived,    Boolean, :default => false
  # the join table is bolted onto the person model
  def people
    Person.all(:project_ids => id)
  end
end