Showing posts from 2014

Why GUIDs Are a Bad Choice for SQL Server Key and Identity Columns

I've spent many years debating with my fellow developers across all manor of subjects (I do love to talk), but one subject that comes up time and time again is the usage of the UNIQUEIDENTIFIER data type in SQL Server; especially when they're used as identity and key columns. In fact, I see this more often than you would expect, and misconfigured UNIQUEIDENTIFIER columns can create "hidden" problems that can be difficult to discover and / or rectify, depending on the SQL experience throughout your team. If you care to ask around your colleagues, it's almost guaranteed that you'll get multiple conflicting opinions on why you should or should not use GUIDs in SQL Server, but few developers actually realise the impact of such a design choice. In the interests of science, I'll try and keep this as factual as possible, and I'll focus on the topic at hand, rather than GUIDs / UUIDs in general. Here's a list of common reasons for using a GUID in your d

Moq'ing Successive Calls to a Method - void method exception handling

My last post expanded on a piece of code I found on Phil Haack's blog that extends Moq to allow you to return different values on each successive call to a method - I also improved it to allow you mock up any of the iterations to throw an exception in place of the return value. This is great for methods that actually return values, but what happens when you want to throw optional exceptions when you invoke void methods in Moq? Well, void methods on Moq mocks return ISetup<TMock> instead of ISetup<TMock, TResult>, which means that you can't use the ReturnsInOrder method to handle exceptions. Normally, you would just append a .Throws() to the respective Setup method, but Throws() has no params[] parameter, and no Action based override (as Returns() does), so the only way to apply this kind of rule is with recursive callbacks, which are both cumbersome and hard to read. This is demonstrated below; I'm mocking up a call to an FTP class. The first and third calls