以单一形式创建第 3 级 child - Rails 5

Question

我正在 ROR 上构建一个简单的 top-to-bottom 日常锻炼应用程序。我可以在同一个表格上创建锻炼日 (parent) 和锻炼 (child)。但是当我提交表单时，我似乎无法保存加权集（grandchild）。有趣的是，由于保存了锻炼，我可以转到该锻炼编辑页面，添加一个加权集，加权集将显示在锻炼日显示页面中。我认为这与加权集在创建时未与练习相关联有关。如何将三个模型绑定在一起？我知道我很接近！

我全app on github. I the link isn't working, try this URL https://github.com/j-acosta/routine/tree/association

型号

class WorkoutDay < ApplicationRecord
  has_many :exercises, dependent: :destroy
  has_many :weighted_sets, through: :exercises

  accepts_nested_attributes_for :exercises
  accepts_nested_attributes_for :weighted_sets
end

class Exercise < ApplicationRecord
  belongs_to :workout_day, optional: true
  has_many :weighted_sets, dependent: :destroy

  accepts_nested_attributes_for :weighted_sets
end

class WeightedSet < ApplicationRecord
  belongs_to :exercise, optional: true
end

锻炼日控制器

class WorkoutDaysController < ApplicationController
  before_action :set_workout_day, only: [:show, :edit, :update, :destroy]

  ...

  # GET /workout_days/new
  def new
    @workout_day = WorkoutDay.new

    # has_many association .build method => @parent.child.build
    @workout_day.exercises.build

    # has_many :through association .build method => @parent.through_child.build
    # @workout_day.weighted_sets.build
    @workout_day.weighted_sets.build

  end

  ...

  # POST /workout_days
  # POST /workout_days.json
  def create
    @workout_day = WorkoutDay.new(workout_day_params)

    respond_to do |format|
      if @workout_day.save
        format.html { redirect_to @workout_day, notice: 'Workout day was successfully created.' }
        format.json { render :show, status: :created, location: @workout_day }
      else
        format.html { render :new }
        format.json { render json: @workout_day.errors, status: :unprocessable_entity }
      end
    end
  end

  ...

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_workout_day
      @workout_day = WorkoutDay.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def workout_day_params
      params.require(:workout_day).permit(:title, exercises_attributes: [:title, :_destroy, weighted_sets_attributes: [:id, :weight, :repetition]])
    end
end

新的锻炼日表格

<%= form_for @workout_day do |workout_day_form| %>
  <% if workout_day.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(workout_day.errors.count, "error") %> prohibited this workout_day from being saved:</h2>

      <ul>
      <% workout_day.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div>
    <%= workout_day_form.label :title, 'Workout Day Name' %>
    <%= workout_day_form.text_field :title %>
  </div>


  exercise_field will go here
  <div>
    <%= workout_day_form.fields_for :exercises do |exercise_field| %>
        <%= exercise_field.label :title, 'Exercise' %>
        <%= exercise_field.text_field :title %>
    <% end %>
  </div>

  weighted_set_fields will go here
  <div>
      <%= workout_day_form.fields_for :weighted_sets do |set| %>
        <%= render 'exercises/weighted_set_fields', f: set %>
      <% end %>  
  </div>

  <div>
    <%= workout_day_form.submit %>
  </div>
<% end %>

Answer 1

罪魁祸首是workout_day_params。在表单中，weighted_sets 字段嵌套在 workout_day 下。但是在 workout_day_params 中，您在 exercises_attributes 下有 weighted_sets_attributes，这就是您遇到问题的原因。将其更改为以下应该可以解决问题。

def workout_day_params
  params.require(:workout_day).permit(:title, exercises_attributes: [:title, :_destroy], weighted_sets_attributes: [:id, :weight, :repetition])
end

ActiveRecord::HasManyThroughCantAssociateThroughHasOneOrMany‌Reflection

这是由于错误的联想。您应该考虑像下面这样调整您的关联

class WorkoutDay < ApplicationRecord
  has_many :weighted_sets, dependent: :destroy
  has_many :exercises, through: :weighted_sets

  accepts_nested_attributes_for :exercises
  accepts_nested_attributes_for :weighted_sets
end

class Exercise < ApplicationRecord
  has_many :weighted_sets, dependent: :destroy
  has_many :workout_days, through: :weighted_sets
end

class WeightedSet < ApplicationRecord
  belongs_to :exercise, optional: true
  belongs_to :workout_day, optional: true
end

以单一形式创建第 3 级 child - Rails 5

Create 3rd level child in a single form - Rails 5

ruby-on-rails

has-many-through

nested-form-for

ruby-on-rails-5

型号

锻炼日控制器

新的锻炼日表格