Converting Acts_As_Tree to Acts_As_Nested_Set

Hello,

I have a tree structure that needs to be converted into a nested set. A great deal of work has already been done on the tree items, so maintaining the integrity of the id's is mandatory. However I need the ability to access entire branches of the tree, which is what Nested set does. Does anyone have any suggestions on how to efficiently transfer the tree to the nested set and create the left and right boundaries?

Thanks!

Awesome_Nested_Set looks interesting as well. Maybe I should use that?

anyone have any ideas?

Mindtonic wrote:

anyone have any ideas?

You should definitely use awesome_nested_set instead of acts_as_nested_set. The former has much cleaner code.

If the size of your tree allows it, I would choose to recreate it using awesome_nested_set using move_to instead of figuring out a smart algorithm for conversion. It'll spare you development time and guarantee a proper conversion.

Is awesome_nested_set a better choice than better_nested_set? I found the following on the better_nested_set wiki page:

Migrating from acts_as_tree

In reference to migrating from acts_as_tree Krishna Dole said, “If you have multiple trees in your table, it is a little more complicated. You first need to give each tree scope (add a tree_id column) and then run the above method on a member of each tree.”

Not completely understanding that statement, I set out to implement it in a migration. Here is my result which appears to work. In this example, I am using a model named Categories:

class ConvertCategoriesToNestedSet < ActiveRecord::Migration   def self.up     add_column :categories, :lft, :integer     add_column :categories, :rgt, :integer     add_column :categories, :root_id, :integer

    # Convert existing tree to nested set with scope     Category.reset_column_information # So the new root ids get saved     Category.renumber_all     Category.roots.each do |r|       r.all_children.each do |c|         c.update_attribute(:root_id, r.id)       end       r.update_attribute(:root_id, r.id)     end   end

  def self.down     remove_column :categories, :lft     remove_column :categories, :rgt     remove_column :categories, :root_id   end end

Mindtonic wrote:

Is awesome_nested_set a better choice than better_nested_set? I found the following on the better_nested_set wiki page:

Yes. Use awesome_nested_set instead.

Migrating from acts_as_tree

In reference to migrating from acts_as_tree Krishna Dole said, �If you have multiple trees in your table, it is a little more complicated. You first need to give each tree scope (add a tree_id column) and then run the above method on a member of each tree.�

Not completely understanding that statement, I set out to implement it in a migration. Here is my result which appears to work. In this example, I am using a model named Categories:

Never read and thought of that, but that should work great!

Every time I tries to run the migration, the rake aborted saying that there is a missing attribute 'name', which is definitely present in the model. Also, the awesome_nested_set rdocs fail to rake... rendering the concept useless as there is very little online documentation. Oh well...

SOLUTION:

You're not going to believe this.

1. Install the plugin 2. Write and run a migration to add `lft` and `rgt` integer columns to your model 3. Change `acts_as_tree` to `acts_as_nested_set` in your model 4. Open the Console 5. type: NameOfYourModel.rebuild!

That's it!

Woah, I've been looking for this for weeks. I hope it helps somebody out there.