无法通过关联使用 has_many 写入未知属性 `followings_count`

Question

虽然与 Rails 关联，但我正在尝试使用 has_many 5。保存“类别”时出现此错误。

ActiveModel::MissingAttributeError in CategoriesController#create

can't write unknown attribute followings_count

以下模特：

class Following < ApplicationRecord  
  belongs_to :category, touch: true, counter_cache: true
  belongs_to :followed_category, counter_cache: :followers_count, class_name: 'Category'
end

类别模型：

class Category < ApplicationRecord
    has_many :followings
    has_many :followed_categories, through: :followings
    
    has_many :followers, foreign_key: :followed_category_id, class_name: 'Following'
    has_many :follower_categories, through: :followers, source: :category
end

类别控制器：

class CategoriesController < InheritedResources::Base
  private
    def category_params
      params.require(:category).permit(:name, :description, :display_in_navbar, post_ids: [], followed_category_ids: [])
    end
end

_form.html.rb

<%= simple_form_for(@category) do |f| %>
  <%= f.error_notification %>
  <%= f.error_notification message: f.object.errors[:base].to_sentence if f.object.errors[:base].present? %>

  <div class="form-inputs">
    <%= f.input :name %>
    <%= f.association :followed_categories, as: :check_boxes %>
  </div>

  <div class="form-actions">
    <%= f.button :submit %>
  </div>
<% end %>

Answer 1

计数器缓存似乎正在寻找类别 table 上名为 followings_count 的列。当你在那里时，我猜你也可能失踪了 followers_count。这帮助我更好地理解它 https://redpanthers.co/counter-cache-how-to-get-started/