PHP Access Control System

I was in similar situation few months ago. I found that tools like Zend_ACL work great if you just check access level to single item (or reasonably low number of them). It fails when you need to get a huge list of items the user is allowed to access. I crafted custom solution to this problem using Business Delegate pattern. BD provides business logic that can be applied in specific context. In this scenario a SQL logic was delivered and used as filtering condition in subselect. See the following diagrams:

_{(source: epsi.pl)}

And sequence diagram that illustrates calls order:

_{(source: epsi.pl)}

I blogged about this solution, unfortunately it's all in Polish, but you may find pieces of code and diagrams handy. What I can say, the implementation is not a piece of cake, but performance-wise it's a champion when compared to iterative access checking for each element on the list. Moreover, the infrastructure above handles not only one type of items on the list. It can serve when accessing different lists, be it list of cities, countries, products, or documents as long as items on the list implement IAuthorizable interface.

Don't know about the details of your problem but the Zend Framework has a rather potent ACL and AUTH set of components you may want to look at. Good stuff like very precise access control, storing data for persistance, advanced conditional rules.

It seems to me like what you need is this: (I'll use a country/state/city example)

1. A list of all countries. Each "country" has an ID.
2. A list of all States within countries. Each state is bound to the ID of the coutnry, but also has its own unique ID.
3. A list of all cities. Each city is bound to either a state, or directly to a country, and has a flag to indicate which.

For a city user, obviously search for and display only those records pertaining to the city that matches their ID. For a state or national level though, search for all records pertaining to each city that has an ID matching that nation (or state or what have you).

So basically, each sub group is dependant on the group above it, and although I don't recall correctly, I believe you can use sub queries to do the trick from there.