不断得到“无法找到没有 ID 的 Model_name"；编写“新"方法时 [英] Keeps getting "Cannot find Model_name without ID" when writing 'new' method

问题描述

作为背景，我目前有三个模型，School、Course 和 Section，它们都是一对多的关系(学校has_many 课程和课程has_many 部分，相应的belongs_to 关系也在模型中建立).我还有以下资源(排除项稍后设置):

As background, I currently have three models, School, Course and Section, where they are all in a one-to-many relationships (School has_many courses, and Course has_many sections, with the corresponding belongs_to relationships also established in the model). I also have the following resources (exclusions to be set later):

  resources :schools do
    resources :courses
  end
  resources :sections #not part of the nest

尽管 sections 可以作为嵌套资源的一部分工作，但自从 Rails guide 强烈建议嵌套仅一层深.

Although sections could work as part of the nested resources, I kept it out since the Rails guide strongly recommended nests only one layer deep.

所以，我的麻烦在于创建一个新部分(在 SectionsController 中)，并通过 course_id

So, my trouble is when it comes to creating a new section (In SectionsController), and having it linked to the course via the course_id

  def new
    @course = Course.find(params[:id]) #this line results in an error
    @section = @course.sections.new
  end

第一行总是会引发没有 ID 就找不到课程"错误，尽管尝试了使用 :id、:course_id 等的各种不同组合，但我无法解决这个错误.由于 Course 是一个嵌套资源，我还缺少其他什么东西吗?感谢您的帮助！

The first line would always raise an "Couldn't find Course without an ID" error, which I can't get past, despite trying various different combinations of using :id, :course_id, etc. Since Course is a nested resource, is there something else that I'm missing? Thanks for your help!

运行 rake routes 时，输出如下:

When running rake routes, here is the output:

         sections  GET    /sections(.:format)                            sections#index
                   POST   /sections(.:format)                            sections#create
      new_section  GET    /sections/new(.:format)                        sections#new
     edit_section  GET    /sections/:id/edit(.:format)                   sections#edit
          section  GET    /sections/:id(.:format)                        sections#show
                   PUT    /sections/:id(.:format)                        sections#update
                   DELETE /sections/:id(.:format)                        sections#destroy
    school_courses GET    /schools/:school_id/courses(.:format)          courses#index
                   POST   /schools/:school_id/courses(.:format)          courses#create
 new_school_course GET    /schools/:school_id/courses/new(.:format)      courses#new
edit_school_course GET    /schools/:school_id/courses/:id/edit(.:format) courses#edit
     school_course GET    /schools/:school_id/courses/:id(.:format)      courses#show
                   PUT    /schools/:school_id/courses/:id(.:format)      courses#update
                   DELETE /schools/:school_id/courses/:id(.:format)      courses#destroy
           schools GET    /schools(.:format)                             schools#index
                   POST   /schools(.:format)                             schools#create
        new_school GET    /schools/new(.:format)                         schools#new
       edit_school GET    /schools/:id/edit(.:format)                    schools#edit
            school GET    /schools/:id(.:format)                         schools#show
                   PUT    /schools/:id(.:format)                         schools#update
                   DELETE /schools/:id(.:format)                         schools#destroy
              root        /   

推荐答案

您需要在新的部分请求中包含这些参数

you need to have these params in your new section request

{:School_id=> some_id, :course_id=>some_id}

这样你就可以让他们与课程绑定

So that you can get them section binding with course

在节控制器

 def new
    @school = School.find(params[:school_id])
    @course = @school.courses.where(:id=>params[:course_id]).first
    @section = @course.sections.new
  end

希望这会治愈:)

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