Rails has_many：通過with：條件。我如何創建關聯？

Question

我有以下與has_many通過條件相關的模型。

（注意Membership驗證kind屬性的存在）

class User < ActiveRecord::Base 
    has_many :memberships 
    has_many :founded_groups, 
    :through => :memberships, 
    :source => :group, 
    :class_name => 'Group' 
    :conditions => {'memberships.kind' => 'founder'} 
    has_many :joined_groups, ... # same as above, but the kind is 'member' 
end 

class Group < ActiveRecord::Base 
    has_many :memberships 
    has_many :founders, ...  # these two mirror the User's 
    has_many :regular_members, ... # 
end 

class Membership < ActiveRecord::Base 
    validates_presence_of :user_id 
    validates_presence_of :club_id 
    validates_presence_of :kind # <-- attention here! 

    belongs_to :user 
    belongs_to :group 
end 

滑軌似乎喜歡上面的代碼（至少其不向吠叫它）。但隨後發生這種情況：

> user = User.create(...) # valid user 
> club = Club.create(...) # valid club 
> user.founded_clubs = [club] 

ActiveRecord::RecordInvalid: Validation failed: kind can't be blank 

> club.founders << user 

ActiveRecord::RecordInvalid: Validation failed: kind can't be blank 

我假設軌道將採取我的代碼{'memberships.kind' => 'founder'}部分和創建關聯的時候使用它，但它似乎並不如此。所以新會員的kind是空白的，並且會引發錯誤。

有沒有一種簡單的方法來創建協會，而不是一個完整的痛苦？

Answer 1

這將工作肯定：

> user = User.create(...) # valid user 
> club = Club.create(...) # valid club 
> user.memberships.create(:club_id => club.id, :kind => 'founder') 

我不知道，但是這可能工作：

> user.memberships.create(:club => club, :kind => 'founder')