ASP.NET MVC ,Maintaining Model State between Ajax requests

Question

problem: On first full page request, my controller invokes an applicationServices Layer (Web Service Proxy to my business tier) in order to populate a collection of current services that is stored in my own controller base class property. This is then to be displayed within a view. Everything within the context of that controller has access to this "Services Collection". Now when i make further calls to the same action method via an AJAX Call, i obviously hitt a different instance of that controller meaning my services collection is empty.

So other than re-getting the whole collection again, where would i store this collection so it gets persisted between ajax requests? Should i persist it as a seperate DomainModel Object, Session object?....as ViewData is not working for me obv. Excuse my MVC ignorance :)

Any help would be greatly appreciated :)

Answer 1

The web is essentially stateless and MVC helps you to go down to the metal, that is, MVC does not try to make something stateful that isn't, which is mostly the path of ye olde ASP: Each request is a request of it's own and it shouldn't know anything about any other request that has been performed in the past.

I feel it is easiest to go down exactly that route, because it it tends to stay clean, fast and helps you in adhering to best practices such as separation of concerns.

AJAX takes this a step further: The idea of AJAX is that a simple 'delete' operation can be implemented as such, ie you only need to authorize and perform one very small query on the persistence layer. That's it. You don't even need to pass a modified page back to the user. A simple machine-readable success/error indication via JSON is sufficient.

If you start to pull lots of services around for small AJAX requests, you really lose most of what it's good for.

I'd also suggest you don't store a bunch of services in a base controller. Chances are that for most requests, you will only need a small subset of these. It's best practices to retrieve only those service you absolutely positively need.