# Application Architecture - Nested Resources **URL:** \ **Category:** Rails\ **Created:** [January 20, 2009, 2:40pm UTC](https://www.ruby-forum.com/t/application-architecture-nested-resources/158201 "2009-01-20T14:40:15Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![KRD](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/94ad74/32.png) [@KRD](https://www.ruby-forum.com/u/KRD)\ **Post date:** [January 20, 2009, 2:40pm UTC](https://www.ruby-forum.com/t/application-architecture-nested-resources/158201/1 "2009-01-20T14:40:15Z")
All, This is will be a bit long winded but here goes… I am working on a medical records application that will provide a web interface (HTML) and REST web services. The application supports many users and many facilities (clinics, hospitals, etc,). A user can belong to more than one facility and have a different set of permissions at each facility. So far I have modified the restful authentication and restful acl plugins to deal with a current user and current facility context. In a web application a simple drop list of facilities that user can access is enough to change the current facility context of that user. As I was considering the REST interface to the application, I decided that it would be to cumbersome for a user to call a resource to change their current facility (not RESTful?). Instead I am kicking around the possibility of using nested resources. When a user accesses [http://localhost/facility/2/patients](http://localhost/facility/2/patients), I change the current facility context based on the URI. I tested the idea and it works. I am concerned that it may get too complex with URIs such as /facility/ 2/patient/123/vitalstatistics (although it makes perfect sense to me). I have a number of articles expressing the nesting should not go beyond 1 level. 1. Would it make more sense to have a URI to change the facility context or extract it from a normal resource URI e.g. /facility/2/ patient/3? 2. In the case of nesting, would it be acceptable to use more than one level in this scenario? 3. When modifying controllers to work in a nested configuration (easy enough), what is the recommended way of constructing filters to handle complex relationships. For example: user profiles, facilities and patients all have a state and country code (multiple foreign key relationships). My guess is that this could get ugly in very quickly. Most examples show only simple one-to-many relationships when it comes to nesting. If anyone has done something similar before and can offer any insight, it would be greatly appreciated. Even a pointer to an existing code base would be enough. Thanks in advance, Keith ---
**Author:** ![KRD](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/94ad74/32.png) [@KRD](https://www.ruby-forum.com/u/KRD)\ **Post date:** [January 20, 2009, 10:52pm UTC](https://www.ruby-forum.com/t/application-architecture-nested-resources/158201/2 "2009-01-20T22:52:25Z")
On Jan 20, 7:39 am, KRD [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > So far I have modified the restful authentication and restful acl > I am concerned that it may get too complex with URIs such as /facility/ > 2/patient/123/vitalstatistics (although it makes perfect sense to > me). I have a number of articles expressing the nesting should not go > beyond 1 level. I wonder if you’re not missing a model here, something that represents the patient-at-a-facility combination. I’m not sure what it would be called, let’s just call it a “registration” for now, something that scope’s a patient’s data to a particular facility. Then you’d have URLs like: /registrations/123/vitals You’d still have /facilities and /patients for the “master” lists of each, but a specific patient-facility combination would be represented by a registration record (i.e., on the model side, facility has\_many :patients :through =\> :registrations). A Registrations controller could then be a simple RESTful interface on top of that. Does that help? Jeff [purpleworkshops.com](http://purpleworkshops.com) [switchingtorails.com](http://switchingtorails.com) ---
**Author:** ![KRD](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/94ad74/32.png) [@KRD](https://www.ruby-forum.com/u/KRD)\ **Post date:** [January 20, 2009, 11:35pm UTC](https://www.ruby-forum.com/t/application-architecture-nested-resources/158201/3 "2009-01-20T23:35:29Z")
Thanks, Sort of… the reason I want to nest ‘encounters’ under facilities (I would have a facility has\_many :encounters :through =\> :registrations, I am still at the conceptual stage) is so I can extract the facility id and set the current facility context for security purposes, much like the concept of a current user. I didn’t want to make the user call a separate URI in order to do this. Are you suggesting that I could get the “encounter” first and then use the model association to get the facility? If so didn’t think of that 🙂 although that would mess with the way restful\_acl works. Thanks for taking the time to answer as I worded my question in a not so succinct manner! Keith