问题更新has_many：通过记录

Question

我遇到了通过记录更新has_many的问题。这里是我的设置：

class TastingGroup < ActiveRecord::Base 
    has_many :group_wine 
    has_many :wines, through: :group_wine 
end 

class GroupWine < ActiveRecord::Base 
    belongs_to :tasting_group 
    belongs_to :wine 
end 

class Wine < ActiveRecord::Base  
    has_many :group_wine 
    has_many :tasting_groups, through: :group_wine 
end 

我试图用这个了acts_as_list，因为在TastinGroup事情葡萄酒的订单，所以我添加了一个“位置”属性的GroupWine模型。

但是，当我尝试更新GroupWine记录时，出现以下错误，这是我正在做的。

gw = GroupWine.first 
#<GroupWine:0x007fd9f7c38b50> { 
     :wine_id => 1, 
     :tasting_group_id => 1, 
     :position => nil 
} 

gw.position = 1 
gw.save 

这里是我的错误...

ActiveRecord::StatementInvalid: Mysql2::Error: Unknown column 'group_wines.' in 'where clause': UPDATE `group_wines` SET `position` = 3 WHERE `group_wines`.`` IS NULL 

什么用NULL为group_wines升起来了，为什么它补充说，where子句？

谢谢。

Answer 1

尝试复数化的group_wine对象group_wines

class TastingGroup < ActiveRecord::Base 
    has_many :group_wines 
    has_many :wines, through: :group_wines 
end 

class GroupWine < ActiveRecord::Base 
    belongs_to :tasting_group 
    belongs_to :wine 
end 

class Wine < ActiveRecord::Base  
    has_many :group_wines 
    has_many :tasting_groups, through: :group_wines 
end