在保存一系列子模型时，我需要将更新的参数传递回父模型。
例如，如果通过一个项目保存一堆员工到每个任务，我需要让项目知道它的一些任务的标题发生了变化，那么我需要收集所有发生变化的标题并在 ProjectObserver 中进行处理。这可能吗？
我意识到可能没有办法按照我尝试的方式进行这项工作。如果不是，我很高兴听到有关如何解决此问题的建议。
这是我没有成功的尝试：
class Employee < ActiveRecord::Base
has_many :employee_tasks
has_many :tasks, :through => :employee_tasks
accepts_nested_attributes_For :employee_tasks
accepts_nested_attributes_For :tasks
end
class Project < ActiveRecord::Base
attr_accessor :changed_employees
has_many :tasks
end
class Task < ActiveRecord::Base
has_many :employee_tasks
has_many :employees, :through => :employee_tasks
belongs_to :project
accepts_nested_attributes_For :employee_tasks
end
class EmployeeTask < ActiveRecord::Base
#this is what I want to accomplish
before_save do
if self.employee_id_changed
self.task.project.changed_employees ||= []
self.task.project.changed_employees << self.employee_id_changed
end
end
belongs_to :task
belongs_to :employee
end
class ProjectObserver < ActiveRecord::Observer
observe :project
def after_save(project)
puts project.changed_employees
# should print out the changed attributes loaded from EmployeeTask
#send a single email with all the updated titles (not one email for each change)
end
end