NHibernate

A few days ago a friend emailed me the following question regarding NHibernate mappings for a solution he’s currently developing: “I have an idea entity that has a collection of comment entities and I need to get the comment count for each idea. I made a massive mistake at the beginning by calling idea.Comments.Count (even worse, I did it in the view!), which due to the collection being lazy-loaded caused about 10 database calls so performance was sluggish even with second level cache. I was therefore wondering how you would do it – would you use HQL and use Comments.size or would you do something differently?” ...

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. ...

The inimitable Ayende Rahien is close to releasing version 1.0 of his NHibernate Profiler tool, and it really is shaping up to be a rather lovely little addition to my developer toolbox. In much the same way that we can use SQL Server Profiler to monitor database activity, and ANTS Profiler to monitor the performance and memory usage of .NET applications, NHProf profiles the activity of the data access layer (NHibernate), and even goes as far as providing helpful hints for potential improvements. ...

Tobin blogged earlier this week about how quality ORM tools like NHibernate make it easier to code to normalized schemas. Here’s a corollary for you: The use of ORM tools doesn’t absolve the need to maintain good database design principles, and even NHibernate won’t save you from your own stupidity. Following an application upgrade release last night, I’ve spent a disproportionate amount of today trying to debug the following exception, which appeared to originate in an area of the codebase which I personally had heavily modified: ...

My name is Ian Nelson. I’m a recovering SQL addict. It’s been four weeks since my last stored procedure. One of my reasons for leaving my cosy permanent job and entering the scary cut-throat world of freelancing was to get a broader exposure to different tools, technologies and methodologies, while remaining with my feet planted firmly in the .NET universe. So, when I got offered a position in a team who were using Subversion, Monorail, Ext.JS, NUnit, Oracle and NHibernate, I jumped at the opportunity. ...

There’s so much good open-source .Net development going on these days – .Text, nGallery, nUnit, etc – it’s a really interesting time to be a developer. My colleague Colin just drew my attention to nHibernate, an object persistence library for relational databases. TheServerSide.net has an excellent article summarising its use. Having just finished a long project where a large amount of time was spent writing “plumbing” code to persist objects to and from a SQL Server database, I’m finding the idea of using an O/R mapper such as this very appealing the next time round. Just as incorporating the MS DAAB block into solutions has reduced the amount of data access code required, I’m hopeful that embracing frameworks such as nHibernate will leave us with more time to spend focusing on addressing the business needs and less on re-solving technical issues. ...