I just had an email from a friend asking where business logic should go when using MVC – the controller or the model. I thought I’d share my reply: I think asking whether the business logic should go in the Model or the Controller is a false dichotomy. There are different kinds of business logic, and there’s also the possibility of putting it somewhere else entirely. Much business logic does indeed belong in the model, particularly stuff like encapsulating calculations and projections, adding meaning to raw data properties, and ensuring domain objects are maintained in a valid state. I see this as the traditional side of OO design – encapsulating logic and restricting accessibility. ...

When I first started writing automated unit tests for my code, I remember getting carried away writing lots of tiny little tests, each with a single Assert. It felt good initially to see all those green ticks, but rapidly became a maintenance headache, and I am now happier having fewer less-brittle tests that do more. I think it’s great when tools like AutoMapper provide powerful methods like… …allowing me to test large swathes of the system configuration with a single, stable test. ...

I’ve been asked “How do you test LINQ queries?” a couple of times in the past few months, so I thought I’d blog my answer for the benefit of all you lovely people. Firstly I should explain how I’ve been doing most of my data access in recent months. I find that the Repository pattern, and particularly the .NET implementation described here by Fabio Maulo meets the vast majority of requirements I have in my applications, and I fall back on additionally using custom DAOs when required. ...

I’ve done a fair bit of WCF development recently (and amazingly I came out of it relatively unscathed, both psychologically and emotionally). Using Castle Windsor’s WCF Facility helped a great deal, but I still found myself writing a fair bit of infrastructure and plumbing code. I thought I’d blog some of these code snippets lest I forget, and on the offchance they might help others. One of the things I wanted to achieve was to ensure that any unhandled exceptions that propagated to the top of the stack were logged. The following custom EndpointBehavior achieves that. I’m using Castle Logging Facility here, but you could of course swap out the logging code for whatever error handling code you require. ...

Here’s another custom WCF EndpointBehavior I found useful recently. Not content with logging all unhandled errors, I wanted to output a DEBUG level log message before and after every operation invocation. As before, I’m using the Castle Windsor Logging Facility to handle my logging, but you can swap that out for your logger of choice if required. Firstly, here’s the EndPointBehaviour itself. This adds a custom CallContextInitializer to every service operation: ...

OK, my last WCF-related code snippet of the day, I promise. This is quite similar to the last one. I required that the WCF service I was developing started a new NHibernate Session for each invocation, and closed it after invocation (i.e. session-per-request). I couldn’t rely on the ASP.NET session start and end events in global.asax as this particular WCF service was to respond to MSMQ messages rather than HTTP. ...

If you’ve recently moved across to ASP.NET MVC development following years of wrangling with the leaky abstraction that was WebForms, you may have encountered some seemingly curious behaviour when posting back to the same URL. Suppose we have the following simple, contrived and utterly imagination-free model: Here’s a view: And here’s the controller: Note that we have two separate Index actions – one for HTTP GET which instantiates and displays a new FooModel instance, and one for HTTP POST which modifies one of the properties on the posted FooModel instance before re-rendering the view. ...

This blog post comes to you live from a Starbucks in the north of England. Yesterday I wrapped up another eight months’ stint contracting at my old haunt Marshalls Plc. It’s been a genuinely interesting gig, working on two distinct greenfield projects using bang up to date technologies including .NET 4.0 and MVC2. But it hasn’t just been a benefit for my CV, I think Marshalls might have got a little something out of the arrangement too, as Marshalls’ Development Manager Sion Harrison commented yesterday: ...

I’ve just become aware of this MoreLINQ project containing some neat IEnumerable extensions authored by the inimitable Jon Skeet. I particularly like the look of DistinctBy – that’s gotta be a lot easier than passing custom instances of IEqualityComparer into Distinct(). Fun fact – I used to work with someone who went to school with Jon Skeet! True Story!

A couple of weeks ago, early one morning, my friend and fellow coder Scott asked a curious question: “Do you think that programming computers for a living gives you a negative outlook on life?” Now, Scott is unfortunately responsible for administering occasional TLC to a codebase that I cut as long ago as 2004, so I assumed he was referring to this and was about to raise some complaints about my hand-rolled query object criteria framework or other coding horror. I steeled myself to defend my work as he continued to explain: ...

Oh, the irony!

@Jez tweeted last night: @ianfnelson admit it: you use Castle Windsor primarily to highlight and lampoon Google’s poor selection of adwords?! — 𝚂𝚑𝚘𝚘𝚝𝚒𝚗𝚐 𝚂𝚌𝚒𝚕𝚕𝚢 (@shootingscilly) October 26, 2009 Funny, but not true. I am enamoured with the Castle Windsor project because its power makes it fairly simple for me to develop loosely-coupled systems which are easily maintained and tested. The wide range of Facilities and Contrib projects also integrate nicely with the other parts of my current development stack (NHibernate, WCF, WF, log4net). ...

The shiny new system which I’ve recently been developing makes heavy use of the Chain of Responsibility pattern, and as such a number of service classes take an array of objects in the constructor: I’m using Castle Windsor for dependency management, so I’ve been fluently registering all instances of ILeadAllocator: Easy, right? And yet at runtime Windsor surprised me by throwing this exception in my face: C M K – a a e s r y l t s s e l h a e a ( d . l c A M l o l i s m l c . p o r L o c o e n a K a e t e d n o r s t r n . s s e A l p w w . p i h H l t i a i h c n c h d a s l t p w e i e a r o c s s n i . S f n H e i o a r c t n v d i k r l c e e e e y g r . s i E L ) s x e t c a e e d r p A e t l d i l . o o n c : a t C i a o n n ’ S t e r c v r i e c a e t e i s c o w m a p i o t n i e n n g t f & o # r 8 2 t 1 h 6 e ; M f a o r l s l h o a w l i l n s g . L d e e a p d e s n . d A e p n p c l i i e c s a : t i o n S e r v i c e . L e a d A l l o c a t i o n S e r v i c e ’ a s i t h a s d e p e n d e n c i e s t o b e s a t i s f i e d . Huh?! What gives? Well, a little Googling revealed this post from Castle founder Hamilton Verissimo explaining that by default the Castle MicroKernel expects me to define what should be included in the array. But he goes on to explain that the behaviour I desire can be achieved by registering a custom subresolver with the microkernel. That subresolver has since been included in the Castle Windsor distro, so in actual fact all I needed to do was add the following line of code when configuring my container: ...

Benny George, our precocious two-year-old, is quite the fan of Mister Maker, and enjoys spending time doing arty crafty stuff with his mum. Now, the great thing about the BBC is that they tend to suggest projects which can be created using bits and bobs that you’re likely to have around the home – old cereal boxes and the like. But occasionally some specialist resources have to be procured in the name of Ben’s art, and so it was that Joce today spent £1.99 on a pack of the “googly eyes” so beloved of Maker. ...

I always knew my lifestyle choices would come back to bite me some day… I’ve been making heavy use of the Castle Windsor container to handle dependency and configuration management in the shiny new system that I’m currently developing. For the most part it’s been an absolute blast, allowing me to easily create a loosely-coupled system architecture and focus my efforts on what the system should be achieving for the client, rather than worrying about how it all hangs together. ...