# Question about acts\_as\_tree **URL:** \ **Category:** Rails\ **Created:** [December 5, 2007, 9:19pm UTC](https://www.ruby-forum.com/t/question-about-acts-as-tree/122242 "2007-12-05T21:19:35Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [December 5, 2007, 9:19pm UTC](https://www.ruby-forum.com/t/question-about-acts-as-tree/122242/1 "2007-12-05T21:19:35Z")
Hi All, I was wondering if a Class declared with acts\_as\_tree can have more than one root, i.e., parent\_id = null? this will basically support multiple trees within the same table. My implementation idea is to have a lookups table where the records that have parent\_id are the lookup Types and each one of those will have several children - and children could have more children, etc. I know I can achieve the same thing for creating a dummy root and make the first level my “types”, but I thought the idea above is cleaner in my opinion. thanks, Marcelo. ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [December 6, 2007, 3:34am UTC](https://www.ruby-forum.com/t/question-about-acts-as-tree/122242/2 "2007-12-06T03:34:47Z")
I’ve been tackling acts\_as\_tree in trying to write forum software. The original posts are each a root, with the replies as children. So, yes, you can have as many roots as you want. The challenge I am faced with is how to traverse a full tree to get the last post??? ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [December 6, 2007, 3:38am UTC](https://www.ruby-forum.com/t/question-about-acts-as-tree/122242/3 "2007-12-06T03:38:19Z")
Types… you mean like “topics”, right? I feel that going with a forums + topics + posts database schema is a much better idea than acts\_as\_tree, but that’s just me. On Dec 6, 2007 6:49 AM, removed\_email\_address@domain.invalid [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > have several children - and children could have more children, etc. > > I know I can achieve the same thing for creating a dummy root and make > the first level my “types”, but I thought the idea above is cleaner in > my opinion. > > thanks, > > Marcelo. > > > – Ryan B. ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [December 6, 2007, 3:44am UTC](https://www.ruby-forum.com/t/question-about-acts-as-tree/122242/4 "2007-12-06T03:44:46Z")
Ryan–Can you explain the “I feel that going with a forums + topics + posts database schema is a much better idea than acts\_as\_tree” a little more? Are you suggesting that ‘topic’ be segregated into it’s own table? Now I have now a forums + (posts w/topics) schema. ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [December 6, 2007, 4:11am UTC](https://www.ruby-forum.com/t/question-about-acts-as-tree/122242/5 "2007-12-06T04:11:05Z")
> Are you suggesting that ‘topic’ be segregated into it’s own table? Now I > have now a forums + (posts w/topics) schema. Indeed I am suggesting this. A forum has many topics, topics have many posts and then posts belong to topics. I find it easier to delete all posts from a topic this way (instead of iterating through all the posts and then deleting all of their children, it’s basically a DELETE FROM `posts` WHERE `topic_id` = ‘topic.id’). I also allow for topics to have their own subjects. I’ve never found a use for a tree view in a forum system. If anyone has anything to say about another post I find that they [quote] the relevant sections of the first post and then reply to it. On Dec 6, 2007 1:14 PM, yachtman [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > On Dec 6, 10:37 am, “Ryan B.” [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > > > have several children - and children could have more children, etc. > > > Ryan B. – Ryan B. ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [December 6, 2007, 4:50am UTC](https://www.ruby-forum.com/t/question-about-acts-as-tree/122242/6 "2007-12-06T04:50:19Z")
For some reason when I posted the message before yours I had a feeling like it was going to get shot down in flames (for a reason that still evades me, I guess the Internet’s conditioned me). Instead, it got praised. Thanks 🙂 I was “inspired” by vBulletin and phpbb. On Dec 6, 2007 1:58 PM, yachtman [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > > > a > > > > > I feel that going with a forums + topics + posts database schema is > > > > more > > > > > > – > > > > Ryan B. > > > > – > > Ryan B. – Ryan B. ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [December 6, 2007, 3:23pm UTC](https://www.ruby-forum.com/t/question-about-acts-as-tree/122242/7 "2007-12-06T15:23:10Z")
Oh great, So quick question: (maybe two!) 1 - What happens when you call the root() method? 2 - how do you get a specific root()? 3 - How do you get all the roots? thanks, ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [December 6, 2007, 4:29am UTC](https://www.ruby-forum.com/t/question-about-acts-as-tree/122242/8 "2007-12-06T04:29:13Z")
Ryan, Thanks for the help. I’ve been designing schemas for years and I don’t know why that layout didn’t occur to me. Yikes. It’s so darn simple. I’ve already got it implemented and it works great. ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [December 6, 2007, 3:31pm UTC](https://www.ruby-forum.com/t/question-about-acts-as-tree/122242/9 "2007-12-06T15:31:23Z")
To get all of the roots…parent\_id will be null (this is a requirement of acts\_as\_tree) parent\_posts = Post.find(:all, :conditions =\> “parent\_id is NULL” A specific root, you’ll need the id… post = Post.find\_by\_id(id) Not sure what calling the root method means…