访问活动记录关系时出现奇怪错误
我有这些模型：
class Segment :segment_code, :primary_key => :code end class Family :segment_code, :primary_key => :code has_many :genus, :foreign_key => :family_code, :primary_key => :code end class Genus :family_code, :primary_key => :code has_many :commodities, :foreign_key => :genus_code, :primary_key => :code end class Commodity :genus_code, :primary_key => :code end 当我调用这个rails console irb命令序列时，我收到此错误，我失去了请帮助。 我也在想我可能需要使用很多：通过。 对我的数据模型的批评也很受欢迎。
这是错误： NameError: uninitialized constant Family::Genu
irb(main):003:0> @genus = Genus.first ←[1m←[35mGenus Load (15.6ms)←[0m SELECT `genus`.* FROM `genus` LIMIT 1 => # irb(main):004:0> @genus.family ←[1m←[36mFamily Load (0.0ms)←[0m ←[1mSELECT `families`.* FROM `families` WHERE `families`.`code` = 10100000 LIMIT 1←[0m => # irb(main):005:0> @family = @genus.family.first NoMethodError: undefined method `first' for # from C:/Ruby192/lib/ruby/gems/1.9.1/gems/activemodel-3.1.0/lib/active_model/attribute_methods.rb:385:in `method_missing' from C:/Ruby192/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/attribute_methods.rb:60:in `method_missing' from (irb):5 from C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.0/lib/rails/commands/console.rb:45:in `start' from C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.0/lib/rails/commands/console.rb:8:in `start' from C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.0/lib/rails/commands.rb:40:in `' from script/rails:6:in `require' from script/rails:6:in `' irb(main):006:0> @family = @genus.family => # irb(main):007:0> @family.genus NameError: uninitialized constant Family::Genu from C:/Ruby192/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/base.rb:1335:in `compute_type' from C:/Ruby192/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/reflection.rb:173:in `klass' from C:/Ruby192/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/association.rb:118:in `klass' from C:/Ruby192/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/association.rb:166:in `find_target?' from C:/Ruby192/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/collection_association.rb:323:in `load_target' from C:in `load_target' from C:/Ruby192/lib/ruby/gems/1.9.1/gems/activerecord-3.1.0/lib/active_record/associations/collection_proxy.rb:89:in `method_missing' from C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.0/lib/rails/commands/console.rb:45:in `start' from C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.0/lib/rails/commands/console.rb:8:in `start' from C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.1.0/lib/rails/commands.rb:40:in `' from script/rails:6:in `require' from script/rails:6:in `' irb(main):008:0>
它被复数forms的Genus / Genera（不是Genu / Genus）所迷惑，并且正在删除’s’以进行单一化。 在config / initializers / inflections.rb中修复此问题
ActiveSupport::Inflector.inflections do |inflect| inflect.irregular 'genus', 'genera' end
在这种情况下，您需要更改has_many：
class Family < ActiveRecord::Base belongs_to :segment, :foreign_key => :segment_code, :primary_key => :code has_many :genera, :foreign_key => :family_code, :primary_key => :code end
或者您可以这样做，这是不正确的英语，但会使您现有的代码工作：
ActiveSupport::Inflector.inflections do |inflect| inflect.uncountable %w( genus ) end