Rails hash tree to array

Question

I'm trying to parse a large XML file. I'm using Saxerator.

My hash has a kind of tree:

obj= {
  "id"=>'1', "groups" =>{
  "group" =>[
   {"id"=>"2", "groups"=>{}},
   {"id"=>"3", "groups"=>{}},
   {"id"=>"4", "groups"=>{
     "group"=>[
       {"id"=>"5", "groups"=>{}},
       {"id"=>"6", "groups"=>{}},
     ]}}
]}}

I don't know in advance the depth of the tree. I had a problem. I have no idea how convert it in array. Result should be like this:

[{"id"=> "1", "parent_id"=> "0"},
{"id"=> "2", "parent_id"=> "1"},
{"id"=> "3", "parent_id"=> "1"},
{"id"=> "4", "parent_id"=> "1"},
{"id"=> "5", "parent_id"=> "4"},
{"id"=> "6", "parent_id"=> "4"}]

Have any ideas?

Your code is malformed. Please fix it.

Yossi
– Yossi

2014-06-02 10:34:15 +00:00
Commented Jun 2, 2014 at 10:34 — Yossi
– Yossi, Commented Jun 2, 2014 at 10:34
Your hash is not valid ruby code.

Yevgeniy Anfilofyev
– Yevgeniy Anfilofyev

2014-06-02 10:40:20 +00:00
Commented Jun 2, 2014 at 10:40 — Yevgeniy Anfilofyev
– Yevgeniy Anfilofyev, Commented Jun 2, 2014 at 10:40
What code you have tried till now ??

Saurabh
– Saurabh

2014-06-02 10:40:48 +00:00
Commented Jun 2, 2014 at 10:40 — Saurabh
– Saurabh, Commented Jun 2, 2014 at 10:40
Is it too large for DOM/XPath?

Mark Thomas
– Mark Thomas

2014-06-02 13:29:44 +00:00
Commented Jun 2, 2014 at 13:29 — Mark Thomas
– Mark Thomas, Commented Jun 2, 2014 at 13:29

amnn · Accepted Answer · 2014-09-14 08:36:05Z

5

You're looking for a very simple recursive function, which linearises the tree but also keeps track of the parent:

def tree_to_a(tree, p = 0)
  id = tree["id"]
  (tree["groups"]["group"] || [])
    .flat_map { |sub| tree_to_a(sub, id) }
    .unshift("id" => id, "parent_id" => p)
end

edited Sep 14, 2014 at 8:36

answered Jun 2, 2014 at 11:02

amnn

3,71620 silver badges24 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Sanket · Accepted Answer · 2014-06-02 11:08:10Z

I have modified your object I hope its correct.

obj= {
  "id"=>'1', "groups" =>{
  "group" =>[
   {"id"=>"2", "groups"=>{}},
   {"id"=>"3", "groups"=>{}},
   {"id"=>"4", "groups"=>{
     "group"=>[
       {"id"=>"5", "groups"=>{}},
       {"id"=>"6", "groups"=>{}},
     ]}}
]}}

Then this your solution.

result = []
def create_hash(result, obj, id)
  result << {id: obj['id'], parent_id: id}
  if obj['groups']['group']
    obj['groups']['group'].each do |g|
      create_hash(result, g, obj['id'])
    end
  end
end
create_hash(result, obj, 0)
result // [{:id=>"1", :parent_id=>0}, {:id=>"2", :parent_id=>"1"}, {:id=>"3", :parent_id=>"1"}, {:id=>"4", :parent_id=>"1"}, {:id=>"5", :parent_id=>"4"}, {:id=>"6", :parent_id=>"4"}]

Collectives™ on Stack Overflow

Rails hash tree to array

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related