Acts_as_tree_on_steroids plugin
posted by gchatz 79 commentsIn this article:
We’ve been using a home-made extension of acts_as_tree on our production site for quite some time. We finally found some time to release it as a plugin You can find it on github. It’s not anything special, but it may give you some ideas for doing similar things.
In a nutshell
Extend classic acts_as_tree, acts_as_nested_set to support:
- Fetching descendants with one sinqle query
- Fetching anscestors with one single query
- Fetching the root node of a node with one query
- Store the level of each node
- Store the children count of each node
- Configure a “family” based on the level (depth) that can be different from the root node
Why?
The problem with classic acts_as_tree is that you need a large number of queries to retrieve the ascendants or descendants of a node. If you want the path of a node with a level of N , you need N – 1 queries. If you want all the children and grandchildren and so forth , you need to recurse at least N times. This can become a pain if your tree is more than 3 or 4 levels.
Acts as nested set offers functionality to retrieve all descendants of a node with a single query, but you can’t do the same for ancestors which is very usefull for a number of things (i.e breadcrumbs)
If your application offers a hierarchical based browsing, you’ll probably need to query the tree all the time to create breadcrumbs or lists with subcategories. Classic examples are ecommerce applications, price comparison sites etc.
Families:
In ecommerce applications it’s very common to have families of products or categories. For example:
Electronics | -> Computers & Peripherals | --> Storage | ----> Hard Disks | --------> SSD
The root node of SSD is Electronics but that’s not the actually family of products because it covers a really big range. The actual family (depending on the application logic) can be Computers & Peripherals or Storage. If family_level is set to 1 for example, the family will be Computers & Peripherals.
Installing
As a plugin:
script/plugin install http://github.com/bandito/acts_as_tree_on_steroids.git
Usage
Your model must have the following database tables:
- parent_id (lnteger)
- id_path (string)
- children_count (integer)
- level (integer)
Optionally you can enable family support by adding the following column.
- family_id (integer)
You should add indexes for id_path, parent_id and family_id (level and children_count will probably have a low cardinality , but you can index them anyway)
Then include the helper in your model.
class Category acts_as_tree_on_steroids :family_level => 1 end
How does it work
When a node is created or changes parent the id_path reflects the node path from the root to the node as a comma seperated value of ids.
For example a really small tree would look like this
1
1,2
1,2,3
1,2,4
1,5
1,6
1,6,11
1,6,11,17
20
20,21
20,21,22
20,21,23
20,21,23,25
If we want to get the descendants of node with id_path 1,6 then we would query for “id_path like ‘1,6,%’” which would match 1,6,11 and 1,6,11,17.
The database will use the index on id_path since it’s not starting with a wildcard.
Likewise, if we wanted the ancestors of the node with id_path 1,6,11,17 we would just query for “id in (1,6,11,17)” to get them with a single query.
When to use it
- You have a category tree that rarely changes but you are doing breadcrumbs and tree representations all the time.
- You have the need to query for i.e products that belong to the current node and the descendant nodes
When not to use it
- If your tree changes frequently then the overhead of the tree traverse can be a pain.
- You don’t need to know the hierarchy of the node.
Comments (79)
Can a nested resource be from other Models? For example, make belongs_to :manufacture and make has_many :series through => product.
When creating a new make I can create an association to a manufacture or when creating a new product I can create an association to manufacture, model and series?
Thank you for your topic
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When not to use it
* If your tree changes frequently then the overhead of the tree traverse can be a pain.
* You don’t need to know the hierarchy of the node.
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When to use it
* You have a category tree that rarely changes but you are doing breadcrumbs and tree representations all the time.
* You have the need to query for i.e products that belong to the current node and the descendant nodes
If your tree changes frequently then the overhead of the tree traverse can be a pain.
We didn't make it , but we are close:
* Your comment must be at least 10 characters
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Thank you very much this information.
Thanks admin very nice post
nice post.
thanks for useful info...
thats good very good.
# You have a category tree that rarely changes but you are doing breadcrumbs and tree representations all the time.
Really cool post - thank you very much - the post help me :-)
This new version is very useful especially to know the hierarchy of nodes which is very crucial for me at least.
It 's really hard for me. May be, I have to learn a lot of things.
Thanks. It 's a nice plugin.
It 's a nice plugin.
Thanks your text is good
Great plug in I'll make use of this.
Got it downloaded and installed with no problems thanks guys.
Seems to be an application that helps you to make your job simpler! It is a welcome change when we get suggestions like this which will help us save time but at the same time, not lose the quality of our work. With all the details given, it won't be difficult for anyone to try it! They have also tipped us with when and when not to use it and the reasons for doing so!! So this home-made extension plug will definitely make your work easier especially in the fields of ecommerce applications, price comparison sites, etc. Good work and keep going!!
Got it downloaded and installed with no problems thanks guys.
good post. I like this post
Interested post, like the name inparticular. Good article, found useful. cheers
Like this, its interesting. Now I go to install the plugin :-)
using tree for programming method is very useful, specially for large number queries..
Your site is very nice touches on a beautiful subject
Thanks werry good!
Thank you for this blog post. The commenter, then, becomes the critic who shapes the writer's next content. So I want to encourage you to keep on blogging in the same style as you writing style is really perfect.
That is rather particular and rather great to acknowledge that we have such an opportunity to overcome all the obstacles and enjoy reading one’s thoughts and ideas which could be of great help and value in our everyday life.
thanx for all :)
your text is good
Thanks for this blog post. The commentator, then the critic, the content forms the next writer. Therefore, I encourage you to continue blogging in the same way that the writing style is perfect.
This new version is very useful to know the particular hierarchy of nodes, which is very important to me at least. Really cool post - thank you very much
well worth the read.I found it very informative as I have been researching a lot lately on practical matters such as you talk about...
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thank u my dae
This new version is very useful to know the particular hierarchy of nodes, which is very important to me at least. Really cool post - thank you very much
Found it a great launch
I thank you very much
Appreciation and respect
I liked your topic
I wish you success
Thanks a lot bijuterii.
thank u my dae
Great idea. Faster is definitely better.
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The problem with classic acts_as_tree is that you need a large number of queries to retrieve the ascendants or descendants of a node. If you want the path of a node with a level of N
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you have the need to query for i.e products that belong to the current node and the descendant nodes
I think you'll receive pretty interesting responses, this article will be very beneficial to many people in more than one ways. Thanks for posting!
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I would not recommend it at all. If you like simple things, than just keep it simple. Complicated things are complicating your life.
Can you further explain this: You should add indexes for id_path, parent_id and family_id (level and children_count will probably have a low cardinality , but you can index them anyway)
Thanks!
Why? Come on. I had tried 4 or 5 times with no luck. Maybe I have the brain of an monkey or maybe it's just not as nicely laid out.
cool, thanks
When a node is created or changes parent the id_path reflects the node path from the root to the node as a comma seperated value of ids.
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Nice tool to have in the webmaster's pocket. Love to see such kind of nice tool introducing posts. Making a bookmark of it. Will catch you every time you give something new.
I never tried steroids, but this plugin is interesting.
Intresting pluggin whats the plugin in for?
Acts_as_tree_on_steroids plugin is usedfull,It causes inquiry more convenient .
adherheahrh
It all helped me a lot. I saved time and I less stressed right now after reading it and doing it. Thank you for your input.
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