I have made this post over a year ago, and I think it makes sense to update it as it’s getting quite a few views.
I’m either missing something out or Microsoft has really messed up MVC. I worked on Java MVC projects and they were clean and simple. This is however a complete mess IMO. Examples online such as NerdDinner and projects discussed on ASP.Net are too basic, hence why they “simply” work. Excuse if this sounds negative, but this is my experience so far.
I have a repository and a service that speaks to the repository. Controllers call service.
My data layer is NOT persistence independent, as the classes were generated by SQL metal. Because of this I have a lot of unnecessary functionality. Ideally I’d like to have POCO, but I didn’t find a good way to achieve this yet.
*Update: Of course Microsoft hasn’t messed anything up – I did. I didn’t fully understand the tools that were at my disposal. The major flaw in what I have done, was that I have chosen a wrong technology for persisting my entities. LINQ to SQL works well in stateful applications as the data context can be easily tracked. However, this is not a case in stateless context. What would be the right choice? Entity Framework code first or code only work pretty well, but what’s more importantly, is that it shouldn’t matter. MVC, or front end applications must should not aware of how data is persisted. *
When creating entites I can use object binding:
[HttpPost]
public ActionResult Create(Customer c)
{
// Persistance logic and return view
}
This works great, MVC does some binding behind the scene and everything is “jolly good”.
It wasn’t “Jolly Good”. Customer was a domain model, and what was worse, it was dependent on persistence medium, because it was generated by SQL metal. What I would do now, is design my domain model, which would be independent of data storage or presentation layers. I would then create view model from my domain model and use that instead.
As soon as I’d like to do some more complex, e.g. – save Order which is linked to the customer everything seems to break:
[HttpPost]
public ActionResult Create(Order o)
{
// Persistance logic and return view
}
To persist an order I need Customer or at least CustomerId. CustomerId was present in the view, but by the time it has got to Create method, it has lost CustomerId. I don’t fancy sitting around debugging MVC code as I won’t be able to change it in a hosting envrionment either way.
Ok, a bit of moaning here, sorry. What I would do now, is create a view model called NewOrder, or SaveOrder, or EditOrder depending on what I’m trying to achieve. This view model would contain all the properties that I’m interested in. Out-of-the-box auto binding, as the name implies, will bind submitted values and nothing will be lost. If I want custom behaviour, then I can implement my own “binding” and it will do the job.
Alternative is to use FormCollection:
[HttpPost]
public ActionResult Create(FormCollection collection)
{
// Here I use the "magic" UpdateModel method which sometimes works and sometimes doesn't, at least for LINQ Entities.
}
This is used in books and tutorials, but I don’t see a point in a method which has an alternative: TryUpdateModel – if this crashes or model is invalid, it attempts to update it either way. How can you be certain that this is going to work?
Autobinding with view models will work the most of the time. If it doesn’t, then you can override it. How do you know it will always work? You unit test it and you sleep well.
Another approach that I have tried is using ViewModel – wrapper objects with validation rules. This sounds like a good idea, except that I don’t want to add annotations to Entity classes. This approach is great for displaying the data, but what do you do when it comes to writing data?
[HttpPost]
public ActionResult Create(CustomViewWrapper submittedObject)
{
// Here I'd have to manually iterate through fields in submittedObject, map it to my Entities, and then, eventually, submit it to the service/repository.
}
** View model is a good way forward. There would have to be some mapping code from view model to the domain model, which can then be passed to the relevant service. This is not a correct way, but it’s one way of doing it. Auto mapping tools are you best friends and you should find the one that suits your requirements, otherwise you’ll be writing tons of boilerplate code.**
Am I missing something out or is this the way Microsoft MVC3 should work? I don’t see how this is simplifying things, especiialy in comparisson to Java MVC.
I’m sorry if this sounds negative, but this has been my experience so far. I appreciate the fact that the framework is constantly being improved, methods like UpdateModel get introduced, but where is the documentation? Maybe it’s time to stop and think for a little bit? I prefer my code to be consistent throughout, but with what I have seen so far, I have no confidence whatsoever that this is a right way forward.
I love the framework. There is so much to learn and it’s not a lot more exciting then it has ever been. Should probably make another post regarding web forms. I hope this is helpful.
I don’t think your issue is with asp.net MVC but with all the pieces You Choose to use together.
You want it raw and simple?
Use POCOs all around, and implement the repository where you need it.
I haven’t used Java MVC, but it’d make the whole question look less like a rant if you include how you solved the particular problem in there.
Let’s clear some misconceptions or maybe miscommunication: