Rails:如何在setter方法中使父属性可用 [英] Rails: How to make available parent attribute in setter method

问题描述

上下文:

我有一个company模型，其中有许多projects和许多tasks. company也有很多employees，而它们又有很多tasks.

I have a company model with many projects, having many tasks. The company also has many employees, which in turn have many tasks.

架构:

问题:

我正在构建一个表单来创建一个项目，用户可以在其中添加多个tasks.提交后，表单应创建单个project记录，一个或多个具有hours和employee_id属性的task记录，并(！)检查数据库中是否已经存在employee名称或创建一个新的

I'm building a form to create a project where the user can add multiple tasks. Upon submission the form should create a single project record, one or more task records with hours and employee_id attributes and (!) check if the employee name already exists in the database or create a new one.

我已经通过在表单中​​添加jquery autocomplete并在Task模型中使用getter和setter方法定义了虚拟属性来实现此目的.类似于铁路#102 .

I've approached this by adding jquery autocomplete to the form and defining a virtual attribute with a getter and setter method in my Task model. Similar to Railscast #102.

此操作成功在tasks中设置了employee_id，并使用员工name和task_id创建了新的employee记录.

This succesfully sets the employee_id in tasks and creates a new employee record with employee name and task_id.

问题是当前模型未保存company_id.

The problem is currently that the model does not save a company_id.

我的代码:

class Task < ActiveRecord::Base
    belongs_to :project
    belongs_to :employee

    def employee_name
      employee.try(:name)
    end

    def employee_name=(name)
      self.employee = Employee.find_or_create_by(name: name) if name.present?
    end
end

问题:

如何使父模型的company_id属性可用于我的Task模型的setter方法?像这样:

How can I make the company_id attribute of the parent model available the setter method of my Task model? Like so:

def shareholder_name=(name)
    self.shareholder = Shareholder.find_or_create_by(name: name, company_id: company_id) if name.present?
end

此刻会产生错误:

undefined local variable or method "company_id" for #<Task:0x98438b8>

或者，如果我尝试project.company_id，这告诉我project是NilClass:

Or, if I try project.company_id this tells me project is a NilClass:

undefined method company_id for nil:NilClass

更新:

仍未解决.为什么在这里project是nil的任何想法?

Still unsolved. Any ideas why project is nil here?

推荐答案

class Task < ActiveRecord::Base
  belongs_to :project
  belongs_to :employee

  def shareholder_name=(name)
    self.shareholder = Shareholder.find_or_create_by(name: name, company_id: project.company_id) if name.present?
  end
end 

还有一个典型的带有Rails的模式，例如您拥有belongs_to :project，它将在Task中添加一个名为project的实例方法，然后该实例方法可用于获取与任务关联的项目，并随后使用如果可能感兴趣的话，关联的company_id

also, so typical pattern with rails, for instance where you have belongs_to :project, that would add an instance method called project to Task, that instance method could then be used to get project associated with task and subsequently the associated company_id in case that may be of interest

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