ActiveRecord嵌套值更新失败

Question

我正在尝试更新产品，请参阅下面的代码。我似乎无法更新类别。欢迎任何帮助。

产品型号：

class Product < ActiveRecord::Base
  belongs_to :category

  accepts_nested_attributes_for :category

  def category_name
    category.try(:name)
  end

  def category_name=(name)
    Category.find_or_create_by(name: name) if name.present?
  end
end

类别模型：

class Category < ActiveRecord::Base
  has_many :products
end

产品控制器：

class ProductsController < ApplicationController
  def index
    @products = Product.all
  end

  def show
    @product = Product.find(params[:id])
  end

  def edit
    @product = Product.find(params[:id])
  end

  def update
     @product = Product.find(params[:id])
     @product.update(products_params)
     redirect_to @product
  end

  private

  def products_params
    products_params = params.require(:product).permit(:name, :category_id, category_attributes: [:category_name])
  end
end