我想在祖父母显示页面下显示孙子记录......我做错了什么？

Question

在我的代码中，一个用户有学生，一个学生有日记，日记有diary_entries。我想在学生展示页面下展示每个学生的日记条目。以下是我的模型。

Student.rb 型号

class Student < ApplicationRecord
  belongs_to :user
  has_many :diaries, dependent: :destroy
  has_many :teams, dependent: :destroy
  has_many :subjects, dependent: :destroy
  belongs_to :grade

  accepts_nested_attributes_for :diaries
  accepts_nested_attributes_for :subjects
  accepts_nested_attributes_for :teams
end

Diary.rb 型号

class Diary < ApplicationRecord
    belongs_to :student
    belongs_to :user
    belongs_to :grade
    has_many :diary_entries

    validates :diary_year, presence: true

    def self.from_student(owner, student_obj)
        new(
            user_id: owner.id,
            student_id: student_obj.id,
            grade_id: student_obj.grade_id,
            diary_year: Date.today.year
        )
    end

end

Diary_entry.rb 型号

class DiaryEntry < ApplicationRecord
  belongs_to :diary
  belongs_to :subject
  belongs_to :user

  validates :lesson_date, :assignment, :assignment_due_date, :notes_to_parents, presence: true
end

日记控制器

class DiariesController < ApplicationController
  before_action :authenticate_user!
  before_action :set_student

  def create
    @diary = Diary.from_student(current_user, @student)
    @diary.save
    redirect_to @student, notice: "Diary was successfully created."

  end

  private

  def set_student
    @student = Student.find(params[:student_id])
  end
end

学生控制器#show

 def show
    @diary = @student.diaries
    @diary_entries = @diary.diary_entries
  end

Diary_entries 控制器#index 和显示

  def index
    @diary_entries = @diary.diary_entries.all
  end

  def show
    @diary_entry = DiaryEntry.find(params[:id])
  end

我希望每个学生每年只有一本日记，所以我在每本日记中添加了一个 diary_year 列，然后在日记中为 student_id 和年份添加了一个唯一索引 table.

  create_table "diaries", force: :cascade do |t|
    t.bigint "user_id"
    t.bigint "student_id"
    t.bigint "grade_id"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.integer "diary_year"
    t.index ["grade_id"], name: "index_diaries_on_grade_id"
    t.index ["student_id", "diary_year"], name: "index_diaries_on_student_id_and_diary_year", unique: true
    t.index ["student_id"], name: "index_diaries_on_student_id"
    t.index ["user_id"], name: "index_diaries_on_user_id"
  end

下面是我在学生展示页面中尝试的循环。

<div class="card">
   <div class="card-body">

     <% @diary_entries.each do |entry| %>
       <li><%= entry.assignment %></li>
     <% end %>
   </div>
 </div>

我希望能够 1. 让每个学生一年只有一本日记， 2. 在每个学生页面下显示 diary_entries。

Answer 1

您想显示 diary_entries 个 Student，请使用 joins

@diary_entries = DiaryEntry.joins(diary: :student)
                           .where(students: { id: @student.id })

关于联接的更多信息 - https://guides.rubyonrails.org/active_record_querying.html#joins

试试吧！

Answer 2

Get each student to have only 1 diary a year,

要每年执行一个日记对象，您可以在日记模型中添加一个 before_validation。参见 Callbacks

回调应该调用私有函数来检查可能冲突的现有记录。

def ensure_valid_year
  return unless student.diaries.where(diary_year: diary_year).any?
  # code or function call here to handle rejection of the new Diary object
end

To show diary_entries under each students page.

您可以在 Student 模型中添加另一个关系。

has_many :diary_entries, through: :diaries

您可以像这样访问相关的 DiaryEntry 对象：

student1 = Student.first
student1.diary_entries

我想在祖父母显示页面下显示孙子记录......我做错了什么？

I want to show grandchildren records under grandparents show page... what am I doing wrong?

ruby-on-rails

rails-activerecord