# RESTful Application Design Question **URL:** \ **Category:** Rails\ **Created:** [August 28, 2007, 2:02am UTC](https://www.ruby-forum.com/t/restful-application-design-question/113142 "2007-08-28T02:02:44Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![mledford](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/90db22/32.png) [@mledford](https://www.ruby-forum.com/u/mledford)\ **Post date:** [August 28, 2007, 2:02am UTC](https://www.ruby-forum.com/t/restful-application-design-question/113142/1 "2007-08-28T02:02:44Z")
Hello all, I’m fairly new to Rails and decided I wanted to give it a go for a fairly simple internal application that I want to refine and use it as the building blocks for possible future applications. The application will act, for now at least, as webservice API used by external applications to POST and GET data. After watching DHH 2006 Rails conference talk I liked the fact that you could use one piece of code with different interfaces. However I feel like I’m coming up against difficultly modeling my domain and the interaction with the external application yet still allowing room for a web interface if required down the road. Essentially what we have are error reporting applications out in the field where those applications are tied to a specific location. The application knows its location and what it is, it looks to use that information to post an error report. The current php version of this application simply posts the data as an Error Report. Doing so kicks off a trigger that inserts into a summary table if the application and location doesn’t exist. With that in mind Here is my current vision for the model. Location (1) --\> (1 … \*) Application (1) --\> (0 … \*) Error Report The problem is a new location and application can come online without being placed into the database prior to reporting an error. Thus the question is, should the external reporting application check to see if its Location and Application exists in the database first by searching, then creating new Location and Application records if required and then POSTing the Error Report? That seems very verbose. It would be nice to simply POST the error report and if required the related data objects created. My questions: 1. Is this possible? 2. If it is possible would it be considered bad practice to have the creation of a resource create other resources? 3. Might there a better way to solve this problem that I just can’t see? Sincerely, Michael ---
**Author:** ![mledford](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/90db22/32.png) [@mledford](https://www.ruby-forum.com/u/mledford)\ **Post date:** [August 28, 2007, 6:07am UTC](https://www.ruby-forum.com/t/restful-application-design-question/113142/2 "2007-08-28T06:07:59Z")
On Aug 27, 7:01 pm, mledford [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Hello all, [snip] > My questions: > > 1. Is this possible? Sure. Consider ErrorReport to be a resource in your application, and post your data to the /errorreports/create action. > 1. If it is possible would it be considered bad practice to have the > creation of a resource create other resources? I don’t think so. Create the other resources as necessary. Just be aware of possible concurrency issues if multiple users are posting error reports simultaneously. > 1. Might there a better way to solve this problem that I just can’t > see? If you prefer, you could require the client application to create the location resource first. If you can make the creation code idempotent, so that multiple calls to create the same location would be handled safely, then you could return an error response code if the location does not exist when they try to create the error report. Then the application would know to first create the location and then try again to create the report. But that seems like the long way around to me. Hope this helps…? > Sincerely, > Michael Jeff > **[Hey Daddio!](http://softiesonrails.com)** > > Home of Hey Daddio Software [essentialrails.com](http://essentialrails.com) ---
**Author:** ![mledford](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/90db22/32.png) [@mledford](https://www.ruby-forum.com/u/mledford)\ **Post date:** [August 28, 2007, 2:07pm UTC](https://www.ruby-forum.com/t/restful-application-design-question/113142/3 "2007-08-28T14:07:08Z")
Hi – On Tue, 28 Aug 2007, mledford wrote: > code with different interfaces. However I feel like I’m coming up > location doesn’t exist. > required and then POSTing the Error Report? That seems very verbose. > It would be nice to simply POST the error report and if required the > related data objects created. > > My questions: > > 1. Is this possible? Sure. > 1. If it is possible would it be considered bad practice to have the > creation of a resource create other resources? Not by me, for several reasons. The resource is “Error report for location x and application y”, and all that matters is that there’s an API for exchanging representations of that resource. How the data behind the representations is persisted (or not) is an implementation detail. And if a new location gets created behind the scenes – and assuming you consider a location also to be a resource, in its own right – that just means that the creation has taken place in some way other than the use of the API. I don’t think there’s anything un-REST-like about that. If, say, your resource is “Jane Eyre”, and you have various representations available (plain text, PDF, movie…), it’s unlikely that any of the data involved were put there via connecting to a URL. I’m putting an emphasis here on [my understanding of] the REST concept of a resource, for which I think the “resource” in Rails resource routing is not necessarily an exact synonym. Nor is that necessarily bad; Rails is not purporting to be a generalized, opinionless (hardly! 🙂 conduit for REST principles, so it make sense that “resource” in Rails tends to evoke very specific persistence techniques and so forth. Still, I think it’s helpful to keep the conceptual nature of resources in view, especially for situations where you need to think through resource and/or storage issues like this. David – - Books: RAILS ROUTING (new! [http://www.awprofessional.com/title/0321509242](http://www.awprofessional.com/title/0321509242)) RUBY FOR RAILS ([Ruby for Rails](http://www.manning.com/black)) - Ruby/Rails training & consulting: Ruby Power and Light, LLC ([http://www.rubypal.com](http://www.rubypal.com)) ---
**Author:** ![mledford](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/90db22/32.png) [@mledford](https://www.ruby-forum.com/u/mledford)\ **Post date:** [August 29, 2007, 1:04am UTC](https://www.ruby-forum.com/t/restful-application-design-question/113142/4 "2007-08-29T01:04:02Z")
I wonder if it is still acceptable to do this in nested resources. For example: POST /locations/100/applications/2/errors Would create location and application if it did not exist and of course create the error. Or should this only create the last resource? Which is my gut feeling. If this is true this brings up a red flag for me… which as David would say mean I need to think about it a little more. Yet, I feel like I’m over thinking this. If you shouldn’t create the referring nested resources then the following pops up. 1. I need the errors resource in two places; /locations/100/ applications/2/errors and /errors 2. These two resources would expect different input for creating vs modifying. /errors would need to have the location and application specified in it’s input where /locations/100/applications/2/errors derives it from the resource. 3. In my mind the output should be the same as the input. If I’m right you would be using the same error report controller but with different routes. It seems like it would be difficult to have two different outputs since the output is usually the underlying model. Any further input would be much welcomed! Sincerely, Michael ---
**Author:** ![mledford](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/90db22/32.png) [@mledford](https://www.ruby-forum.com/u/mledford)\ **Post date:** [August 28, 2007, 3:08pm UTC](https://www.ruby-forum.com/t/restful-application-design-question/113142/5 "2007-08-28T15:08:17Z")
Jeff & David, Many thanks for your thoughtful replies. I will keep them in mind while I proceed down this very new road for me. Sincerely, Michael