在下拉列表中的树层次结构中显示类别/子类别 [英] Show categories/sub-categories in tree hierarchy inside a dropdown

问题描述

我有一个包含字段 id、name 和 parent_id 的类别表.根类别的 parent_id 为 0.现在我想在下拉列表和如下结构中显示类别列表:

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

这是我的控制器:

def new
  @category = Category.new
end   

这是视图:

    <%= f.label :parent_category %>
    <% categories = Category.all.map{|x| [x.name] + [x.id]} %>
    <%= f.select(:parent_id, options_for_select(categories), {}, class: 'form-control') %>

请帮忙.

推荐答案

通过在application_helper.rb中添加这些函数解决了问题

Solved the problem by adding these functions in application_helper.rb

def subcat_prefix(depth)
  (" " * 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

并在我看来像这样使用它们

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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