来自Rails中的一种形式的多个通知？

Question

所以我们有一个 has_many :through 关联。一个教室有_many Students 到 ClassroomStudents。

学生是通过classroom_new 表单以嵌套形式添加的，因此创建ClassroomStudents 需要通过Classroom Controller 而不是ClassroomStudent 控制器。

我正在创建通知，以便在将学生添加到教室时通知家长。但是无论添加多少学生，都只会创建一个通知，并且不会保存学生 ID。如何从一个表单中创建多个通知？

教室控制器创建方法（ClassroomStudenets也在这里创建）

def create
    @classroom = current_user.classrooms.create(classroom_params)
    @classroom_student = ClassroomStudent.new
    @student = @classroom_student.student_id

    respond_to do |format|
      if @classroom.save
        format.html { redirect_to @classroom, notice: "Classroom successfully created." }
        format.json { render :show, status: :created, location: @classroom }
        if @classroom_student.save
          @student = @classroom_student.student_id
          create_notification @classroom, @classroom_student, @student
        end
      else
        format.html { render :new, alert: "Failed to create classroom." }
        format.json { render json: @classroom.errors, status: :unprocessable_entity }
      end
    end
  end

在课堂控制器中创建通知方法

def create_notification(classroom, classroom_student, student)
    Notification.create(user_id: current_user.id,
    #this is temporary, it will soon be the student.parent_id
                        notified_by_id: current_user.id,
                        student_id: classroom_student.student_id,
                        identifier: classroom.id,
                        notice_type: 'add student')

  end

在控制器中定义参数

def classroom_params
    params.require(:classroom).permit(:name, :image, :description, student_ids: [])
  end

  def classroom_students_params
    params.require(:classroom_student).permit(:student_id, :classroom_id, student_ids: [])
  end

课堂新形式

<title>Create a Class - Kidznotes</title>
<div class="authform">
<h2><center>Create a Classroom</center></h2>
<%= simple_form_for @classroom do |f| %>
  <%= f.input :name %>
  <%= f.input :description %>
  <%= f.input :image %>
  <h6>This image will be on your classroom banner</h6>
  <br>
  <%= f.label :classroom_students %>
  <br>
    <div class="form-3-col">
      <%= f.collection_check_boxes :student_ids, Student.all, :id, :first_name %>

    </div>
  <br>
  <%= f.button :submit %>
<% end %>

class Notification
belongs_to :student
belongs_to :notified_by, class_name: 'User'  
end

班级有很多通知，用户也有，但课堂学生或学生没有（学生是帐户类型，他们被视为父母创建的对象）

这是保存在数据库中的内容：

 #<Notification id: 21, user_id: 3, notified_by_id: 3, post_id: nil, identifier: 76, notice_type: "add student", read: false, created_at: "2017-07-11 13:54:11", updated_at: "2017-07-11 13:54:11", student_id: nil> 

我被困在这个问题上的时间比我想承认的要长，所以提前感谢任何反馈。

Answer 1

问题是@classroom_student.student_id 将永远是nil，因为@classroom_student只是ClassroomStudent的新实例 没有任何params。 AFAIK，当使用 many-to-many 关系时，不需要显式保存第三个模型。 你应该改用association.create。也就是说，你不要'根本不需要@classroom_student。您应该从表单访问params[:classroom][student_ids] 并将它们传递给create_notification 方法以创建多个通知。所以你的create 方法应该是这样的

def create
  @classroom = current_user.classrooms.new(classroom_params)
  @classroom.students.create

  #create notifications for multiple students
  params[:classroom][:student_ids].each do |student|
    create_notification @classroom, student
  end
  respond_to do |format|
    if @classroom.save
      format.html { redirect_to @classroom, notice: "Classroom successfully created." }
      format.json { render :show, status: :created, location: @classroom }
    else
      format.html { render :new, alert: "Failed to create classroom." }
      format.json { render json: @classroom.errors, status: :unprocessable_entity }
    end
  end
end

最后，调整您的 create_notification 方法，如下所示

def create_notification(classroom, student)
    Notification.create(user_id: current_user.id,
    #this is temporary, it will soon be the student.parent_id
                        notified_by_id: current_user.id,
                        student_id: student,
                        identifier: classroom.id,
                        notice_type: 'add student')
  end