Mysql 仅删除Rails 4中表之间的连接记录

我有3种Rails型号：

class User < ActiveRecord::Base
  has_and_belongs_to_many :char_factors
end

class CharFactor < ActiveRecord::Base
  has_and_belongs_to_many :users
end

class UserCharFact < ActiveRecord::Base
  belongs_to :user
  belongs_to :char_factor
end

上述措施似乎运作正常。但是我找不到删除两个表之间特定的

连接关系的方法。我尝试了以下方法：

def destroy
  @user_character = CharFactor.find(params[:id])
  @user.char_factors.delete(@user_character)
end

但它实际上是从
CharFactor
表中删除值，而不仅仅是删除关联
您删除它就像删除任何其他模型记录一样

user_char_factor = UserCharFactor.find_by(user_id: user_id, char_factor_id: char_factor_id)
user_char_factor.destroy if user_char_factor

UserCharFact.where（char\u-factor\u-id:params[：id]，user\u-id:@user.id）.全部销毁

user_char_factor = UserCharFactor.find_by(user_id: user_id, char_factor_id: char_factor_id)
user_char_factor.destroy if user_char_factor