我有以下协会代码：
has_many :rates_without_dimension,:as => :rateable,:class_name => "Rate",:dependent => :destroy,:conditions => {:dimension => nil}
has_many :raters_without_dimension,:through => :rates_without_dimension,:source => :rater
has_one :rate_average_without_dimension,:as => :cacheable,:class_name => "RatingCache",:conditions => {:dimension => nil}
dimensions.each do |dimension|
has_many "#{dimension}_rates",:conditions => {:dimension => dimension.to_s},:as => :rateable
has_many "#{dimension}_raters",:through => "#{dimension}_rates",:source => :rater
has_one "#{dimension}_average",:conditions => {:dimension => dimension.to_s}
end
它引发了一个错误：
Unknown key: :conditions. Valid keys are: :class_name,:class,:foreign_key,:validate,:autosave,:table_name,:before_add,:after_add,:before_remove,:after_remove,:extend,:primary_key,:dependent,:as,:through,:source,:source_type,:inverse_of,:counter_cache
我试图将第一行改为：
has_many :rates_without_dimension,-> { where(:dimension => nil) }
但它也引发了一个错误,你能指出我有什么问题吗？
解决方法
这里描述的问题相同
https://teamtreehouse.com/forum/unknown-key-conditions
正如我在示例中看到的,带有条件的lambda应该在关联名称之后执行,因为没有{}的hash只能作为最后一个参数.
尝试
has_many :rates_without_dimension,-> { where(dimension: nil) },as: :rateable,class_name: "Rate",dependent: :destroy
附：你可以使用http://apidock.com/rails/Object/with_options使它看起来更好