Users and nested (yet potentially independent) "groups" in Rails 3?

Question

I'm having a bit of trouble wrapping my head around something. Basically I'm starting a new project that involves groups of groups of groups of groups of…well, you get the idea.

Anyway, the only model that is somewhat "universal" throughout the application is the concept of Users (as they are what determines what privileges any one person has). The problem comes in when you have groups that can "own" other groups. For instance, you can have a "city" chapter that is owned by a "state" chapter that is owned by a "national" chapter, etc. And, each chapter can have their own users when then have rights to all groups below them.

The thing is, though, that no one group is guaranteed to be owned (or used) by another group, so they would need to be independently managed. I can't quite conceptualize what the methodology would be to handle something of this nature. I mean I could probably use some sort of acts_as_nested setup, but I fear even that may get out of hand. Also, as far as the groups themselves are concerned, should I use some kind of inheritance model (given that they would likely share many properties)?

Perhaps I should simply create an individual MVC setup for each group -- although there's still the issue of associating users, etc. Can anyone offer suggestions?

Best

Answer 1

You could create a groups table which self-references. That would keep all your group data in a single table and the magic is done via associations.

Ryan Bates has a railscast that could likely be tweaked to fit your situation. e.g. rather than friendships, having ownerships or something like it.

Edit: Having only a single parent helps. It appears the plugin acts_as_tree will likely work for the task at hand. Ryan Bates happens to have a railscasts epidsode for that plugin as well.

Objectives

1: Allow groups to have children, parents Solution: acts_as_tree

2: Allow groups to potentially become or remain independent. Solution: acts_as_tree. Simply remove the parent_id and the group would become it's own root node

3: Enforce hierarchy (e.g cities cannot have another city as a parent). Solution: This would likely have to be done via a custom validation

4: Users rights inheritance. I anticipated this particular objective to be the most challenging. Of course, I don't know all the in's and outs of what "rights" means to your application, but I'll some assumptions... you fill in blanks where I'm wrong. Once you have the associations between users and groups (and possible "rights" table). Solution: To determine if rights should apply to current_user for current_group, a) check ownership and if not b) transverse up current_group.ancestors until you get an answer or hit the root.

It sounds like a fun project. I wish you luck with it!