Comments on: ASP.NET MVC, TDD and Fluent Validation

By: Drew Freyling

Drew Freyling — Fri, 27 Jan 2012 15:29:12 +0000

You don’t consider throwing exceptions for validation a bit heavy handed? Considering exceptions should really only occur in “exceptional” circumstances and the cost associated with throwing and catching them?

By: Richard

Richard — Mon, 01 Feb 2010 00:48:37 +0000

Martin – good question. In that case you would put a formal API in place that returns API-specific DTOs (effectively the same as a view model, without any specific UI in mind). For example, Twitter’s “get user” method might return the user’s details combined with their last ten tweets.

Then each client queries/send commands to the API, and maps its responses to their own UI-specific view models.

There should hopefully be a blog post about this (API-driven applications) in the next month or three :)

By: Martin Aatmaa

Martin Aatmaa — Sun, 31 Jan 2010 23:23:58 +0000

I agree with the overall flow, but I’m not convinced whether your ViewModels (UserRegistrationForm) should be in the ApplicationServices (UserRegistrationService) layer.

What if your ApplicationServices layer is shared by more than one client? For example, in addition to your Web MVC client, you want to add a Win console app. If this were the case, you ApplicationServices layer would have to know about ViewModels from both client apps, which seems smelly to me.

What do you think?

In any case, thank you for the informative post!

By: Richard

Richard — Fri, 16 Oct 2009 01:38:48 +0000

I haven’t yet, but it wouldn’t be too hard to set up an action filter to do it instead?

By: Wes

Wes — Thu, 15 Oct 2009 21:26:18 +0000

Have you tried using interception/AOP for dealing with validation exceptions?

By: dario-g

dario-g — Tue, 15 Sep 2009 09:31:17 +0000

Your example is in this post exactly suits to use AutoMapper but when you don’t have setters AutoMapper is (almost) not usable.

AutoMapper in my project is something like utility, not required convention. It helps me with simple models. :)

PS
I’m glad to see, that my ideas are so good (I think ;)).

By: Richard

Richard — Tue, 15 Sep 2009 00:11:15 +0000

Dario – we have tried using automapper in the reverse direction (i.e. updating domain model from the view edit model) but found it doesn’t really work because the domain model doesn’t have setters.

By: dario-g

dario-g — Mon, 14 Sep 2009 23:53:13 +0000

It’s amazing. I’ve just implementing like this in my app last night :) wow, wow, wow :)

Difference is with creating domain model. I’m using AutoMaper instead of builders and form data (ViewModel) is passed to service via interface (IUserRegistrationForm instead of UserRegistrationForm).

Do you have any possibility to view my desktop? ;)

By: Jake Scott

Jake Scott — Wed, 26 Aug 2009 02:06:53 +0000

Also attribute based validation is horrible when you want to anything that is not constant based. For example a simple “Date cannot be in the past” is impossible to do with attributes.

By: cowgaR

cowgaR — Sat, 22 Aug 2009 22:04:32 +0000

good work Richard!
I’m in minority using FluentValidation, but I prefer it by all means!

Too bad all the other frameworks, even Microsoft (in upcoming MVC v2) is using attribute-based validation, which is forcing me to use partial classes = no go.