Rails - 如何在创建自引用模型时建立关联？

Question

我有一个 self_referenced 模型（类别）：

class Category < ApplicationRecord
    has_many :sub_themes_association, class_name: "SubTheme"
    has_many :sub_themes, through: :sub_themes_association, source: :sub_theme
    has_many :inverse_sub_themes_association, class_name: "SubTheme", foreign_key: "sub_theme_id"
    has_many :inverse_sub_themes, through: :inverse_sub_themes_association, source: :category

    accepts_nested_attributes_for :sub_themes
end

我想用他的 sub_themes 协会以相同的形式创建一个类别模型。

例如数字 => 类别和 SEO 和编码 => sub_themes

class Admin::CategoriesController < AdminController

  def index
    @categories = Category.all
  end

  def new
    @category = Category.new
    @sub_themes = @category.sub_themes.build
  end

  def create
    @category = Category.new(category_params)
    if @category.save
      redirect_to admin_categories_path
    else
      render :new
    end
  end

  private

  def category_params
    params.require(:category).permit(
      :name,
      sub_theme_attributes: [
        sub_theme_ids:[]
      ]
    )
  end
end

和表格：

<%= simple_form_for [:admin,@category] do |f| %>
  <%= f.error_notification %>
  <%= f.input :name %>
  <%= f.association :sub_themes, as: :select, collection: Category.all, input_html: { multiple: true } %>
  <%= f.submit "Enregister" %>
<% end %>

表单已正确显示，但在创建时出现错误，并且关联未保留。

不允许的参数：:sub_theme_ids

Answer 1

这是一个非常常见的误解，认为您需要嵌套属性来简单分配（现有记录），但事实并非如此。您只需要白名单 category[sub_theme_ids][]:

def category_params
  params.require(:category).permit(
    :name,
    sub_theme_ids: []
  )
end

accepts_nested_attributes_for 仅当您想以相同的形式创建类别及其子主题时才需要。在这种情况下，您需要使用 fields_for（用简单的形式包装为 simple_fields_for）：

<%= simple_form_for [:admin,@category] do |f| %>
  <%= f.error_notification %>
  <%= f.input :name %>
  <%= f.association :sub_themes, as: :select, collection: Category.all, input_html: { multiple: true } %>

  <fieldset>
    <legend>Subthemes</legend>
    <%= f.simple_fields_for(:sub_themes) do |st| %>
      <%= st.input :name %>
    <% end %>
  </fieldset>

  <%= f.submit "Enregister" %>
<% end %>

def category_params
  params.require(:category).permit(
    :name,
    sub_theme_ids: [],
    sub_theme_attributes: [ :name ]
  )
end

Rails - 如何在创建自引用模型时建立关联？

Rails - How to make an association on create for self referenced model?

ruby-on-rails

self-reference

simple-form