ruby-on-rails - 将哈希深度转换为平面路径数组

Question

我想获得有关如何像这样转换不同结构的提示和示例:

h = {
    friend: [:id, :name],
    meta: {
        board: [:id, :name],
        column: [:id, :name, users: [:id, :name]]
    },
    trello: [:id, :name]
}

像这样进入数组:

[[:friend, :id],
 [:friend, :name],
 [:meta, :board, :id],
 [:meta, :board, :name],
 [:meta, :column, :id],
 [:meta, :column, :name],
 [:meta, :column, :users, :id],
 [:meta, :column, :users, :name],
 [:trello, :id],
 [:trello, :name]]

这个数组的每个元素都是一个完整的路径。

Answer 1

非常标准Tree traversal problem .你可以使用 DFS通过递归:

# for Array.wrap; It's needed in pure ruby script, not in Rails
require 'active_support/all'

def deep_flatten(tree, path, result)
  tree.each do |key, value|
    Array.wrap(value).each do |e|
      if e.is_a? Hash
        deep_flatten(e, path + [key], result)
      else
        result << path + [key, e]
      end
    end
  end
end

tree = {
  friend: [:id, :name],
  meta: {
    board: [:id, :name],
    column: [:id, :name, users: [:id, :name]]
  },
  trello: [:id, :name]
}

result = []
deep_flatten(tree, [], result)
result.each do |line|
  puts line.inspect
end

输出:

[:friend, :id]
[:friend, :name]
[:meta, :board, :id]
[:meta, :board, :name]
[:meta, :column, :id]
[:meta, :column, :name]
[:meta, :column, :users, :id]
[:meta, :column, :users, :name]
[:trello, :id]
[:trello, :name]

Array.wrap