Question

在我的rails应用中，我有以下型号

class Member < ActiveRecord::Base
  has_many :trainings
end

class Student < ActiveRecord::Base
  belongs_to :member
  has_many :trainings   #maybe a through relationship here
end

class Teacher < ActiveRecord::Base
  belongs_to :member
end

######编辑#################

class Training < ActiveRecord::Base
  belongs_to :member  #only member not student nor teacher
end

#############################

现在，我如何在学生控制器中构建培训

class StudentsController < ApplicationController
  def new
    @student = Student.new
    @student.trainings.build    #### This is not working
  end
end

由于

Answer 1

如果你使用的是rails 4，你必须在模型中编写accepts_nested_attributes_for并将它们添加到强参数中。像这样：

class Student < ActiveRecord::Base
  belongs_to :member
  has_many :trainings     
  accepts_nested_attributes_for :trainings
end

class StudentsController < ApplicationController
  def new
    @student = Student.new
    @student.trainings.build 
  end

  def create
    @student = Student.create(student_params)
    @student.trainings.build(params[:student][:trainings])

    redirect_to student_path
  end

  #For rails 4

  def student_params
     params.require(:student).permit(:id, :name, trainings_attributes: [ :id, :your fields here ])
    end
end

这是一个可以帮助您的链接： Rails 4: accepts_nested_attributes_for and mass assignment

Answer 2

如果您已正确定义了关联，那么new控制器操作中的代码将起作用（我对其进行了测试）。检查并确保您的Training模型存在，或者您使用了正确的关联名称（也许您的意思是:teachers？）。

应用/模型/ student.rb

class Student < ActiveRecord::Base has_many :trainings end

应用/模型/ training.rb

class Training < ActiveRecord::Base belongs_to :student end

应用/控制器/ students_controller.rb

class StudentsController < ApplicationController def new @student = Student.new @student.trainings.build end end

<强>更新

假设这些是您的关联定义的方式，您可以像这样构建一个范围Training的实例：

应用/模型/ member.rb

class Member < ActiveRecord::Base has_many :trainings end

应用/模型/ student.rb

class Student < ActiveRecord::Base delegate :trainings, to: :member belongs_to :member end

应用/模型/ training.rb

class Training < ActiveRecord::Base belongs_to :member end

应用/控制器/ students_controller.rb

class StudentsController < ApplicationController def new @student = Student.new @student.build_member @student.trainings.build end end

希望有所帮助。

Rails在belongs_to关系中有很多

2 个答案: