复杂类别的下降取决于当前的叶节点。

I have these relationships

我有这些关系

User
 has_many :products
 has_many :stores

Product
 belongs_to :user
 belongs_to :store
 belongs_to :category

Store
 belongs_to :user
 has_many :products

Category
 acts_as_nested_set
 has_many :products

In the homepage( view file ) i have a category drop down similar to amazon's:

在主页(查看文件)中，我有一个类似于亚马逊的分类下拉:

 <ul id="site-category-dropdown">
            <li class="has-dropdown">
                <a href="#">
                    <span class="site-category-dropdown-link-span">
                        <span class="line-1">SHOP BY</span>
                        <span class="line-2">Category</span>
                    </span>

                </a>
                <ul class="dropdown dropdown-box-shadow"> 
                    <% Category.all.each do |root_cat| %>
                        <li class="has-dropdown site-category-dropdown-element">
                            <a href="#" class="site-category-dropdown-element-link"> 
                                <span class="term"><%= root_cat.name %></span>
                            </a>
                                <ul class="dropdown">
                                    <% root_cat.children.each do |children| %>
                                        <li><%= link_to children.name, category_path(id: children.id) %></li>
                                    <% end %>
                            </ul>
                        </li>
                    <% end %>
                </ul>
            </li>
        </ul>

This looks something like the image below ( Root categories and their sub categories is shown on hover) 复杂类别的下降取决于当前的叶节点。

如下图所示(根类别及其子类别显示在悬停状态)

Now i'm on the store page, and i want to show a drop down similar to the site drop down but only for the products that are being sold by the store.
Store products

现在我在商店页面上，我想显示一个下拉列表，类似于站点下拉列表，但只针对商店正在销售的产品。存储产品

Product 1 - (category_id: 46, store_id: 1, product_name: "Prada t-shirt")
Product 2 - (category_id: 47, store_id: 1, product_name: "Prada shoes")
Product 3 - (category_id: 47, store_id: 1, product_name: "Gucci shoes")
Product 4 - (category_id: 12, store_id: 1, product_name: "A classy Dining Table")
Product 5 - (category_id: 12, store_id: 1, product_name: "Kitchen stool")
Product 6 - (category_id: 12, store_id: 1, product_name: "Office Chair")

<br>
cateogory_id 46 is T-shirt in Fashion -> Men -> T-shirt
<br>
category_id 47 is Shoe in Fashion -> Men -> Shoe
<br>
category_id 12 is Furniture in Home -> Furniture
<br>

I'm using the awesome_nested_set gem for the categories (https://github.com/collectiveidea/awesome_nested_set)
i can map all the category_id in an array using: category_ids = @store.products.map(&:category_id)

我正在为类别使用awesome_nested_set gem (https://github.com/collectiveidea/awesome_nested_set)，我可以使用:category_ids = @store.products.map(&:category_id)映射数组中的所有category_id

My question is, how can i build a drop down similar to the site drop down i showed above but only for products sold by this store. Remember the category_id for each products are the category ids for the leaf category, how do i recreate a drop down from the root categories? Using the store products I've given above, it should look something like this: 复杂类别的下降取决于当前的叶节点。

我的问题是，我如何建立一个像我上面展示的网站下拉一样的下拉，但只针对这个商店出售的产品。记住，每个产品的category_id都是叶子类别的类别id，我如何从根类别中重新创建一个下拉列表?使用我上面给出的商店产品，应该是这样的:

1 个解决方案

#1

This might be a naive implementation, but I think it could do the trick.

这可能是一个幼稚的实现，但我认为它可以实现这个目的。

# in your controller
@categories = find_root_categories @store.products.map(&:category_id)

def find_root_categories(leaf_categories)
  leaf_categories.map { |node| find_root(node) }.uniq!
end

def find_root(leaf)
  return leaf unless leaf.parent_id?
  find_root(Category.find(leaf.parent_id))
end

And then you'd iterate over the collection just as you did in your original post. This does incur the overhead that @engineersmnky warned about though, as you'll be making quite a lot of database calls. It might be a good idea to cache all categories in an instance variable before calling find_root:

然后你会迭代这个集合，就像你在最初的帖子里做的那样。这确实会导致@engineersmnky警告的开销，因为您将进行大量的数据库调用。在调用find_root之前，最好在实例变量中缓存所有类别:

# in the controller
@categories = Category.all

def find_root(leaf)
  return leaf unless leaf.parent_id?
  find_root(@categories.find(leaf.parent_id))
end

Please let me know if I've misunderstood something about your question!

如果我误解了你的问题，请告诉我。

#1