Tips

Here’s a PowerShell trap that needs better publicity - if you have both x64 and x86 versions of PowerShell installed (say, as you would on Windows Server 2008 R2), their security policies are independent.

I've been spending much of my time working on a multi-tier system that makes use of special purpose data transfer objects for communication between the service tier and various clients.

These dedicated data transfer objects need to be properly marked up with [DataContract] and [DataMember] attributes, else the object is incomplete when transferred over the wire.

Unfortunately, any errors in the markup weren't apparent at compile time. Instead, they were being discovered either at runtime, when a service call failed outright, or while writing client code, when an expected property was missing from a proxy generated by svcutil.

Enter NUnit to save the day with a cunning unit test.

If you're working on an application that uses custom window chrome - whether you're using Windows.Forms or WPF - then make sure you check out the Marlett font, already installed on your system.

Here's a Visual Studio tip that falls into the category of "obvious once you know it" ...

When you get this error:

Found conflicts between different versions of the same dependent assembly.

To find out further information about which assembly has been found, and which projects are affected, look in the Output window under "Build". You'll find a dense paragraph of information that tells you everything you need to know.

Looking for a way to databind to a paragraph of text in WPF, I first learnt about FlowDocuments, then about Run and how it doesn't support databinding. Further consultation with Professor Google led me to Scott Hanselman's The Weekly Source Code #40 where I found links telling me how to make binding work.

While upgrading the NAntGraph solution to .Net 4, my build script started failing with an inexplicable error:

C:\Projects\NAntGraph\NAntGraph2.sln.metaproj : error MSB4126:
The specified solution configuration "Debug|BNB" is invalid.
Please specify a valid solution configuration using the Configuration and Platform properties
(e.g. MSBuild.exe Solution.sln /p:Configuration=Debug /p:Platform="Any CPU")
or leave those properties blank to use the default solution configuration.

Ever encountered this error?

System.IO.FileLoadException: Could not load file or assembly {0} or one of its dependencies.

I find this particularly frustrating because it doesn't tell you which dependency couldn't be loaded. Aarrgghh!!

Richard Dingwall to the rescue - go download libcheck, a small but very useful tool he's just released on github.

Here's a trap if you're setting up an existing web application on a new IIS 7.5 installation ...

If your web application fails on startup with this error:

The requested page cannot be accessed because the related configuration data for the page is invalid.
There is a duplicate 'system.web.extensions/scripting/scriptResourceHandler' section defined

The likely cause is that you are trying to run a web application written to run on the .NET 2.0 runtime on the .NET 4.0 runtime.

There are three solutions.

If you're crazy enough(*) to be using SSIS to import information from an Excel workbook into a database, you may get an error like this:

Error: SSIS Error Code DTS_E_CANNOTACQUIRECONNECTIONFROMCONNECTIONMANAGER.
The AcquireConnection method call to the connection manager "Time Series XLSX" failed with error code 0xC00F9304.

Creating an IIS hosted web service that uses callbacks and publishes metadata.

Did you know that Visual Studio can play a sound to tell you when the build completed - in fact, different noises to tell you about success and failure? I didn't - but here's how to do it.

Here's a pattern that I've seen occur a number of times - a pair of method overloads, one accepting IEnumerable<T> and the other accepting params T[].

I'm working on a little project at the moment which is dynamically building a WPF user interface based on a configuration file loaded when the application starts. This involves code to manually create all of the bits and pieces that are normally specified directly in a Xaml file.

One useful shortcut I've found is to leverage .NETs built in TypeConverter framework - the same technique used by the Xaml loader itself.

I'm one of the many who've been trying out the Windows 7 Release candidate - yes, I know that it's available retail now, it's on the Christmas list.

One thing that's bugged me is the apparent lack of follow through with Multi-monitor support. You see, if you drag windows around with the mouse, Windows 7 offers some useful auto-dock functionality, but only at the outer edges of the screens.

Sometimes a quick consultation with Professor Google or Doctor Bing just doesn't bring you any satisfaction - and you end up having to work.

Richard Dingwall suggests that when this happens, you should consider blogging about the issue, sharing your experience so that others can benefit. (In many ways, this is a capsule description of all human progress!)

Here's a subtlety of NHibernate mapping that I ran into this morning.

When you map a one-to-many relationship as a list, you can have null values in that list when loaded.

Watch $exception

Here's a useful tip that I didn't know - you can use the pseudo-variable $exception in the Watch window to see the exception that's just been caught.

There's a lot of "goodness" buried in WinForms databinding that doesn't get to see the light of day. Here's one example I discovered just today ...

customer.png

The Class Diagram tooling built into Visual Studio is worth its weight in gold as documentation.

What I didn't know, and discovered today, is that using Copy Image populates the clipboard with not only a raster version of the image, but a vector version as well. Fantastic for embedding into Word documents when writing documentation.

Of all the new features in C# 3.0, Lambda expressions have to be one of my favourites.

One non-obvious way that they can be used is as event handlers, in just the way that anonymous delegates could be.

Here’s a useful technique for finding the location of configuration files.

Each AppDomain has a base directory from which it loads assemblies – when you double click a WinForms or WPF application, the new process that starts up has an AppDomain whose base directory is the directory in which your exe is located.

My whitepaper on WiX techniques has been updated to correct an error.

The previous version of the whitepaper omitted the definition of the "PreventDowngrading" custom action, necessary for proper upgrade behaviour.

The related blog posts (on versioning and upgrading) have also been updated.

A question came up recently on the NZ dot Net mailing list:

Any one use listbox.DataSource = myList for data binding to a List box?

I cannot refresh the data source "myList". If I use the following code to update the data source:

listbox.DataSource = null;
listbox.DataSource = newList;

The items in the listbox are object types rather than data values.

Can any one tell me how to refresh the data in the list box when binding to the control?

My reply was:

Over on 43 Folders (great site, well worth a spelunk or two) there's a great post on getting focused.

I feel these techniques before, and find them quite useful - at least, when I remember to apply them. :-)

One key that has been really useful for me is to pay attention on how I phrase things I add to my TODO list - the template <em>I need to $FOO because I want to $BAR</em> is helpful here.

The .NET framework has lots and lots of built in goodies that aren't well enough known - like built in support for [ensuring only a single copy of the application runs at a time](http://www.hanselman.com/blog/TheWeeklySourceCode31SingleInstanceWinForm...).

Too often, we developers spend ages coding up support for operations that are already there!

I'm sure that most of you know that you can't call methods on a null reference, so you'll expect that this code will fire a nasty exception:

IPath p = null;
int l = p.Length();

Except, it doesn't.

Why?

Following up on my previous post, I've found the cause of the problem.

Here's a quick tip I was shown by a friendly Help Desk guy this week (thanks, Ben!).

Next time you get an error dialog from some random piece of software, don't reach for a pen to write down the relevant details.

Now here's a trick that I didn't know - you can use the [Conditional] attribute to suppress a method unless a given symbol is defined at compile time.

From the MSDN documentation:

Applying ConditionalAttribute to a method indicates ... the method should not be compiled into Microsoft intermediate language (MSIL) unless the conditional compilation symbol that is associated with ConditionalAttribute is defined.

Mostly of use when you're writing logging and other diagnostic code - indeed, major use in the framework seems to be in the Debug and Trace classes.