rails 3 - 在銷燬驗證之前接受嵌套的屬性

Question

我有一個教師模型accept_nested_attributes_for klasses。如果klass中有用戶並且我想打印驗證消息，我不希望能夠刪除該klass。

這是我...

class Teacher < ActiveRecord::Base 
    accepts_nested_attributes_for :klasses, :reject_if => proc { |a| a['name'].blank? }, :allow_destroy => true 
end 

class Klass < ActiveRecord::Base 

    belongs_to :teacher 
    has_many :users 
    before_destroy :reject_if_has_users 

    private 

    def reject_if_has_users 
     if users.length > 0 
     errors.add_to_base "You cannot delete this class as it contains users." 
     false 
     else 
     true 
     end 
    end 

end 

我希望當我嘗試從包含當我使用accepts_nested_attributes_for並傳遞「klasses_attributes」用戶老師取出克拉斯驗證失敗= > {「0」=> {「name」=>「test」，「_destroy」=>「1」，「id」=>「17183」} hash。

如果我沒有error.add_to_base行，上述方法將阻止klass被刪除。它不會導致驗證消息顯示。當我有這條線時，它並不妨礙刪除。

感謝，

添

Answer 1

確認刪除記錄時，保存記錄，只有當沒有發生。我在其中一個項目中處理這個問題的方式是在模型中引發異常，然後從控制器中的異常中解救出來並顯示閃光警報。就像這樣：

型號：

class Klass < ActiveRecord::Base 
    before_destroy :reject_if_has_users 

    private 

    def reject_if_has_users 
    raise "You cannot delete this class as it contains users." if users.length > 0 
    end 
end 

教師控制器：

def update 
    # Code for updating the teacher 
rescue RuntimeError => e 
    redirect_to teacher_url(@teacher, :alert => e.message) and return false 
end