在下拉菜单中显示树状层次结构中的类别/子类别 [英] Show categories/sub-categories in tree hierarchy inside a dropdown

问题描述

我有一个带有字段id，名称和parent_id的类别表。根类别有parent_id 0.现在我想在下拉菜单中显示类别列表以及像这样的结构：

  root_category 
 first_sub_category 
 sub_sub_category 
 another_sub_sub_category 
 second_sub_category 
 another_root_category 
 first_sub_category 
 second_sub_category 
   
 
 $ b 
这是我的控制器：
 
 
  def new 
 @ category = Category.new 
 end 
  
以下是视图：
 <％= f.label：parent_category％> 
 <％categories = Category.all.map {| x | [x.name] + [x.id]}％> 
 <％= f.select（：parent_id，options_for_select（categories），{}，class：'form-control'）％> 
  
请帮助。  
解决方案
  def subcat_prefix（深度）$ b $解决了这个问题b（& nbsp;* 4 * depth）.html_safe 
 end 
 
 def category_options_array（current_id = 0，categories = []，parent_id = 0，depth = 0）
 Category.where（'parent_id =？AND id！=？'，parent_id，current_id）.order（：id）.each do | category | 
类别<< [subcat_prefix（depth）+ category.name，category.id] 
 category_options_array（current_id，categories，category.id，depth + 1）
 end 
 
类别
结束
  
并在我看来像这样使用它们
 <％= f.select（：parent_id，options_for_select（category_options_array），{}，class：'form-control'）％> 
  
 
I have a category table with fields id,name and parent_id. The root categories have parent_id 0. Now i want to show the list of categories in a drop down and a structure like this:
root_category
    first_sub_category
        sub_sub_category
        another_sub_sub_category
    second_sub_category
another_root_category
    first_sub_category
    second_sub_category
Here's my Controller:
def new
  @category = Category.new
end   
And here's the view:
    <%= f.label :parent_category %>
    <% categories = Category.all.map{|x| [x.name] + [x.id]} %>
    <%= f.select(:parent_id, options_for_select(categories), {}, class: 'form-control') %>
Please Help.
解决方案
Solved the problem by adding these functions in application_helper.rb 
def subcat_prefix(depth)
  ("&nbsp;" * 4 * depth).html_safe
 end

 def category_options_array(current_id = 0,categories=[], parent_id=0, depth=0)
  Category.where('parent_id = ? AND id != ?', parent_id, current_id ).order(:id).each do |category|
      categories << [subcat_prefix(depth) + category.name, category.id]
      category_options_array(current_id,categories, category.id, depth+1)
  end

  categories
end
and using them in my view like this
<%= f.select(:parent_id, options_for_select(category_options_array), {}, class: 'form-control') %>


                        
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