Creating a simple logging Interceptor using NInject 3.0

8. October 2013 20:52 by martijn in .net, DRY, ninject

One of the really cool aspects of Depency Injection is the ability to add functionality without changing existing code. A typical example of this might be implementing INotifyPropertyChanged or logging method calls. Using NInject 3.0 Interceptors it is very easy to do this. The interceptor intercepts all calls to the resolved object and allows you to add logging or whatever code you want to run. In NInject 3.0 the methods you intercept do NOT have to be virtual as well :) So how to set it up...

Getting the right assemblies.

Using Nuget just get NInject.Extensions.Interception.Linfu. This will also setup NInject 3.0 and NInject.Extensions.Interception.


Creating the logging Interceptor

This is just a sample interceptor that logs using Console.Writeline. Normally you would call something like Log4Net or your preferred logging framework. Implementing IInterceptor means you have to implement a Intercept method. The Intercept method gets a invocation as a parameter. By invocation.Proceed() the original method gets called. The logger first logs the method being called and the arguments it is called with. After the invocation.Proceed() it logs the result of the method call. The interceptor is pretty simple and can certainly be improved by creating nicer more custom messages.

public class LoggingInterceptor : IInterceptor


        public void Intercept(IInvocation invocation)


            var methodName = invocation.Request.Method.Name;



                var parameterNames = invocation.Request.Method.GetParameters().Select(p => p.Name).ToList();

                var parameterValues = invocation.Request.Arguments;


                var message = string.Format("Method {0} called with parameters ", methodName);

                for (int index = 0; index < parameterNames.Count; index++)


                    var name = parameterNames[index];

                    var value = parameterValues[index];

                    message += string.Format("<{0}>:<{1}>,", name, value);



                //log method called



                //run the intercepted method



                //log method return value

                if (invocation.Request.Method.ReturnType != typeof(void))


                    LogMessage(string.Format("Method {0} returned <{1}>", methodName, invocation.ReturnValue));




            catch (Exception ex)


                var message = string.Format("Method {0} EXCEPTION occured: {1} ", methodName, ex);






        private static void LogMessage(string message)


            Console.WriteLine(string.Format("{0:HH:mm} {1}", DateTime.Now, message));





Adding the logging interceptor to your NInject Configuration

In your kernel configuration you can add interceptors to your bindings like this :


Now when getting a IService using Kernel.Get<IService> the logginginterceptor will be interception all method calls :) A working sample console application can be found here: 

SampleLogging.rar (2.86 mb)

SampleLogging.rar (2.86 mb)




Using bundling to generate base64 encoded images in CSS

9. June 2013 14:59 by martijn in .net, bundling, css

Should I use base64?


In this era of optimization and mobilization having a lot of request to load your website is considered a bad thing. One of the things you can do is 'inline' your images in your CSS file using a base64 format. This way the browser can get the CSS and the images in one big request.

There are some cons to this :

  • Images are not cached separately and when you change your css the download will be bigger.
  • IE6 and IE7 don't support base64 images in CSS. You can use a fallback tag for these browsers.
  • Your development gets more complex as you have to remember to update the base64 images in your css when you modify an image.
  • Images in css are about 37% larger than in a separate file.
  • Works for images up to 37k in IE8
  • Stylesheets get really large 

Also you might consider using a spritesheet which can be cached seperately (like jQuery UI does for example) or create a separate stylesheet for your inlined-images so your cache will not be invalidated when you change something else in you stylesheet. Some more considerations and opinions at Stackoverflow....

Creating a bundle transform to inline the images

So still interested? Some of the development disadvantages can be avoided by using a bundle transform. A bundle transform is part of the System.Web.Optimization library by Microsoft. The basic idea of bundling is combining multiple css or jss files into one big file at runtime. You can configure System.Web.Optimization to only optimize when you are in release mode so that during development you have separate readably resources. This post is about creating a bundle that replaces background-image:url('/yourimage') which base64 urls during optimization.

As you can see the image is inlined (in the 28796 characters) and a fallback for IE6/IE7 is supplied as well. 

This can be done at development time easily with the web essentials extension by Mads Kristensen. The idea of this transform is to perform the operation at runtime. The main advantage is that your development is not cluttered with having to regenerate images and having optimization only on production code.

Here's the code

So let's get into the details. Sorry for the missing syntax highlighting. I have not fixed that yet.


 public class CssBaseEncodeTransform : IBundleTransform


        public void Process(BundleContext context, BundleResponse response)


            response.Content = InlineBase64BackgroundImages(response.Content, BundleTable.MapPathMethod);



        public static string InlineBase64BackgroundImages(string content, Func<string, string> mappath)


            //find background-images


            var parser = new CSSParser();

            var cssDocument = parser.ParseText(content);

            foreach (RuleSet rule in cssDocument.RuleSets)


                var declarations = rule.Declarations.ToList();

                foreach (var declaration in declarations)


                    if (declaration.Name == "background-image")








            return cssDocument.ToString();



        private static Declaration GetIe6Declaration(Declaration declaration)


            var copy = new Declaration();

            copy.Expression = new Expression()


                    Terms = new List<Term>{new Term() {Value = declaration.Expression.Terms.First().Value}}


            copy.Name = "*background-image";

            return copy;



        private static void EmbedUrlInBackground(Declaration declaration, Func<string, string> mappath)


            var imageUrl = declaration.Expression.Terms[0].Value;

            var image = Image.FromFile(Path.GetFullPath(mappath(imageUrl)));

            var data = ImageToBase64(image, ImageFormat.Jpeg);

            var url = string.Format(@"data:image/jpg;base64,{0}", data);



            declaration.Expression.Terms[0].Value = url;




        public static string ImageToBase64(Image image,ImageFormat format)


            using (MemoryStream ms = new MemoryStream())


                // Convert Image to byte[]

                image.Save(ms, format);

                byte[] imageBytes = ms.ToArray();


                // Convert byte[] to Base64 String

                string base64String = Convert.ToBase64String(imageBytes);

                return base64String;





  1. The code basically looks for background-image declarations in your style sheet.
  2. If found replace the url('/image') with the base64 equivalent.
  3. A *background-image declaration is added for IE6/7 support.


Just add the transform to the bundle :

The code use the simple css parser project which can be found here (and is included in the zip). The source code is also included at the bottom. Hope is this of some use or inspiration! (997.47 kb)


Getting typed JSon in TypeScript using Weld

1. June 2013 20:32 by admin in .net, DRY, jQuery, MVC, typescript, Weld
Imagine you have a MVC controller exposing a Person as following: 

public JsonResult GetPerson(int id)
return Json(new Person
First = "Barack",
Last = "Obama"
Now I want to use this client side. I want to update my "first" span with the First property of the person I get back from the server. After messing around I came up with the following: 
$(document).ready(function() {
$.getJSON("/Person/GetPerson/", { id: 4 }, function(data) {
This took me five minutes to get right (which JQuery method? -> Google, how to pass data? -> find example, plus a typo in the first/First member). Five minutes of stupid getting right what should be trivial. Why not let the compiler help? So using Weld I change my server side method to this :
public JsonResult<Person> GetPerson(int id)
return new JsonResult<Person>(Json(new Person
First = "Barack",
Last = "Obama"
}, JsonRequestBehavior.AllowGet)); ;
Basically I wrap my JsonResult in a generic wrapper JSonResult<T> (included with Weld) so that Weld knows what type to expect. Next I add the AjaxMethod Weld attribute. Client side I use TypeScript and use the generated proxy class.  
/// <reference path="Weld/PersonController.ts" />/// <reference path="typings/jquery/jquery.d.ts" />
$(document).ready(function () {
PersonController.prototype.GetPerson(2, (person) => {
Now person is a JavaScript object or a TypeScript 'any' type. No, Person is a fully defined TypeScript interface with a First and Last member just like my C# class. Here's the generated code:
/// <reference path="../typings/jquery/jquery.d.ts" />
class PersonController
GetPerson(id: number, callback: (data: Person) => any)
var url = "/Person/GetPerson";var data = { id: id };
url: url,
type : "POST",
data: data,
success: callback,
interface Person
First: string;
Last: string;
As always in the end there is still JavaScript code generated which you can easily debug. Weld code is simple and clean. Easy huh? And there are more benefits:
  1. If I remove or rename my action-method the TypeScript compiler will detect my breaking client side code at compile time. If you just use javascript you will (hopefully) find out at runtime.
  2. If I add or remove properties from my Person class my changes will cascade to the clientside immediately. 
  3. I get a nice interface clientside making code completion really work 
  4. No more Googling JQuery methods
  5. This is more DRY (Don't Repeat Yourself). For example if you don't like JQuery you can build a Weld template using a different method. Regenate and you are ready
Weld is fully open source and can be found at

Generating TypeScript proxy classes for Ajax Methods using Weld

1. June 2013 19:30 by martijn in .net, jQuery, MVC, typescript, Weld

In this post I want to talk about a little tool called Weld I wrote to make integrating client-side TypeScript and server side MVC C# easy. 

Imagine you have a server-side method that calculates some value you want to use client side. In this sample project I want to calculate the sum of two values I have in input fields.



Server-side I have this action-method in my home controller.

public int Sum(int x,int y)
return x + y;
Now to access this method client I just need to add a Weld attribute. For this I first install Weld using NuGet. 
Just “Install-Package Weld” in your NuGet package manager console. This will install Weld as well a TypeScript.Compile and JQuery typings into your project. 
TypeScript.Compile auto compiles all your typescript files post-build. This enables you to detect any problems caused by server side changes. 
The basic process :
  1. Normal compilation
  2. Weld generates TypeScript code for the classes your decorated with Weld attributes
  3. TypeScript compiles all files in your project with build actions 'TypeScriptCompile'
For this sample I add the AjaxMethod (Weld.Attributes.AjaxMethod) attribute to the ‘Sum’ action. 
Compile the project. Weld now has generated a proxy class for my home controller. I just need to include it and used it in the project. It is located in the /Scripts/Weld folder. 
I add the generated homecontroller.ts to my project. I my main TypeScript file I write the following to hook it all up:
/// <reference path="Weld/HomeController.ts" />/// <reference path="typings/jquery/jquery.d.ts" />
$(document).ready(function () {
$("#btnSum").click(function () {
HomeController.prototype.Sum($("#number1").val(), $("#number2").val(), (result) => {
As you can see the details of the Ajax communication are handled by weld and you get a nice interface to your server side API :)

Creating a Yes/No toggle switch for a boolean property in ASP.MVC

11. May 2013 13:20 by admin in .net, jQuery, JQuery UI, MVC

When editing boolean values in MVC the default option is to use a checkbox. This results in the following Create page when using the default scaffolding


This is fine and works OK but sometimes you want something more..’fancy’. ASP.NET MVC ships with Jquery.UI so why no use the slider of JQuery.UI to create a nice toggle switch?

In this post I will use and modify a JQuery.UI plugin that will result in the following. The plugin is based on which had some errors in my opinion.


There are a two parts to this:

  1. Create a HTMLHelper extension method that renders a <select> element for the boolean property with <option> elements for true and false
  2. Change the rendered <select> element to a jquery slider using a JQuery.UI plugin

Creating the HTMLHelper

public static class HtmlHelperExtensions
public static MvcHtmlString ToggleSwitchFor<TModel>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, bool>> expression)
return htmlHelper.DropDownListFor(expression, new[]
new SelectListItem { Text = "No", Value = "false" },
new SelectListItem { Text = "Yes", Value = "true" } 
}, new { @class = "toggleswitch" });

This adds a HTMLHelper method that renders a dropdown list which comes down to a single select HTML element. There are two options in the select : one for true and one for false. To use it we just do 

@Html.ToggleSwitchFor(model => model.CommentsEnabled)

And we get the following html

<select class="toggleswitch" data-val="true" data-val-required="The CommentsEnabled field is required." id="CommentsEnabled" name="CommentsEnabled"><option value="false">No</option><option value="true">Yes</option></select>

This is all what we need to get our JQuery plugin going.

Creating the JQuery plugin

The plugin uses the JQuery.UI slider to create a toggle switch. This means that any styling or theme you might have for the slider will work for the toggle as well. The plugin transforms the select element into two labels with a slider in between. When you click on a label or move the slider the select control will be updated as well and when you do form post the values get updated. The had two errors when I tried it

  1. The change event was just passing the change event of the slider. This meant even if the boolean property did not change (you moved the slider a little) you would still get a change event. In this version the change event is only fired when the value really changed.
  2. The plugin did not allow chaining.
  3. The normal ‘change’ event of JQuery was no longer fired. This is fixed by not having a change event on the control itself but just fire the existing change event.

To use it you need to add the CSS and JS of the plugin to your page. You also need the default JQuery UI js and css (which is not referenced by default!). Once you have done that you can activate the plugin for a control:

$(document).ready(function () {
$("#CommentsEnabled").toggleSwitch().change(function() {

I attached a sample MVC application as well as the JQuery.UI.ToggleSwitch plugin. (771,1 KB) (1,73 KB)

Adding and removing build targets from NuGet powershell

1. May 2013 15:56 by admin in .net, msbuild, nuget
In NuGet packages you can add powershell scripts to alter the .csproj file of the project in which your package is installed. Recently I had quote some trouble getting this exactly right but nailed it in the end. So here's a sample to share with google so I can find it later ;) This sample adds a target that runs after the AfterBuild target: The Get-Project and Get-MSBuildProject are from the nuget powertools by David Fowlder. (This script is part of the install.ps1 script from a open source project called Weld).

Adding a build target to a project

$project = Get-Project
$buildProject = Get-MSBuildProject
$target = $buildProject.Xml.AddTarget("WeldAfterbuild")
$target.AfterTargets = "AfterBuild"
$task = $target.AddTask("Exec")
$task.SetParameter("Command", "`".\..\packages\Weld.1.0.0\tools\Weld.console`" bin\`$(TargetFileName) `"`$(ProjectDir)\Scripts\Weld`"")
$project.Save() #persists the changes
Notice how the ` (backtick) is used to escape the " and $ characters. This result in the .csproj like this:
<Target Name="WeldAfterbuild" AfterTargets="AfterBuild">
<Exec Command="&quot;.\..\packages\Weld.1.0.0\tools\Weld.console&quot; bin\$(TargetFileName) &quot;$(ProjectDir)\Scripts\Weld&quot;" />
This effectively calls the Weld.Console application passing it the current project .dll name and a target folder.

Removing a build target from a project

In uninstall.ps1 we can remove the same target like this:
$project = Get-Project
$buildProject = Get-MSBuildProject
$projectRoot = $buildProject.Xml;
Foreach ($target in $projectRoot.Targets)
If ($target.Name -eq "WeldAfterbuild")
$project.Save() #persists the changes
Basically we search for target called "WeldAfterbuild" and then remove that from the project! Easy once you know how :)

Setting up LinqToXSD in Visual Studio 2012

28. March 2013 20:29 by admin in .net, linqtoxsd, vs2012, linq


Linq To XSD is a code generation library for accessing xml in a strongly typed manner. Linq to XSD allows you to query and xml file like this:

Offcourse you need a XSD to define the structure of your xml but once you have that the API is much nicer than the general LinqToXML.

Setting it up in Visual Studio

Since it took me way too long and way too much googling to setup LinqToXSD in VS 2012 I thought I'd do 
a HOWTO setup for VS2012. So here's the step by step
  1. Download linqtoxsd from (I used
  2. Extract the zip to ($SolutionDir)\LinqToXSD
  3. Next unload the project in which you want use LinqToXSD (right click -> Unload Project) and edit the project file (right click->edit myproject.csproj)
  4. Now you have to reference the targets file in the LinqToXSD folder. At the top of the file insert the following line:

     <LinqToXsdBinDir Condition="'$(LinqToXsdBinDir)' == ''">$(SolutionDir)\LinqToXSD\</LinqToXsdBinDir>

    So it looks like this
    5. Finally at the bottom of the project file add   

        <Import Project="$(LinqToXsdBinDir)\LinqToXsd.targets" /> 

        below <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
    6. Reload the project
    7. If all is well you can now change the build action of xsd files in your project like this:

    8. Once this is done code is generated which you should be able use immediately. Your xsd/xml has to obey certain restrictions. I included two sample files which should work out of the box here :
books.xsd (,92 KB)
books.xml (,93 KB)

Hope this is of some use and happy easter!

Type safer databinding in legacy forms projects

22. February 2013 10:56 by admin in .net, vs2010 vs2012
I love compilers. I love ReSharper. And that's why i hate statements like this:

<%# DataBinder.Eval(Container.DataItem,"FirstName") %>
If I was to change the name of the FirstName property or would try to find all references to this property this would not work! In 4.5 there is a ItemType property on databinding controls which you can use so the dataitem gets a proper type. See for an explanation about this. Unfortunately not all code is 4.5 and we can not use this feature everywhere. 

In pre 4.5 projects we can use a different construct. On the container of the databinding control we expose a type-safe version on the current dataitem like this:
public Person CurrentDataItem
get { return (Person) Page.GetDataItem(); }
Now in our binding control we can use:
 <%# CurrentDataItem.FirstName %>
No strings involved :) See the attached vs2008 sample project for an example. (27,75 KB)

Closing all sql connections from Solution Explorer.

27. September 2012 17:21 by admin in .net, vs2010 vs2012
In my development work I get the following message quite a lot : Cannot drop database "XXX" because it is currently in use. This usually means I have an existing website or tool with a connection to the database I want to drop. Especially with Entity Framework Code-First I tend to rewrite the whole DB quite often. Instead of killing the 'guilty' process I decided to create a VS shortcut to deal with it. So here's what I have now:

What does this do?

  1. Look for a App.Config or Web.Config of the selected project
  2. Look for connection strings in the configuration file
  3. Use the first connection string and try to connect to the corresponding master db
  4. Close existing connections to the database specified in 3

So HOW does it work?

For this purpose i created a small console application and integrated it into my Visual Studio as an external command. 

The application (source code) is included as a zip file here: (211,17 KB)
This consists of a VS2012 solution but it should be easy to open it in VS2010 as nothing special is done. (For VS2010 just import the .cs files into a 'fresh' project) The heart of the application is the following:

Basically switching between SINGLE_USER and MULTI_USER closes all active connections. 

Next (and final) step is to integrate the program into vs2012. The steps are the same on VS2010 and afaik VS2008. Here's how:
1 Add the program as external tool
Via Tools->External tools click add. Point to the point where you have connection-killer exe file and change the initial directory of the application. Move connection killer up so it is the first external tool (you'll see why later). It should look like this:

2 Create a short in the Solution Explorer context menu
  1. Go Tools->Customize and click the Commands tab. 
  2. Click the context menu 'Project and Solution Context Menus | Project'
  3. Add command select category 'tools' and select command 'External Command 1'
  4. Click 'Modify Selection' and rename the menu item to kill connection or something
  5. Close the dialog and you're done