Project description

CarTrackr is a sample application for the ASP.NET MVC framework using the repository pattern and dependency injection using the Unity application block. It was written for various demos in presentations done by Maarten Balliauw.

CarTrackr is an online software application designed to help you understand and track your fuel usage and kilometers driven.

You will have a record on when you filled up on fuel, how many kilometers you got in a given tank, how much you spent and how much liters of fuel you are using per 100 kilometer.

CarTrackr will enable you to improve your fuel economy and save money as well as conserve fuel. Fuel economy and conservation is becoming an important way to control your finances with the current high price.

Source code

Latest version: CarTrackr (ASP.NET MVC 1.0 version)

Author blog feed

 Maarten Balliauw {blog} News Feed 
Thursday, November 27, 2014  |  From Maarten Balliauw {blog}

When working in larger projects, you will sometimes encounter errors similar to this one: “Could not load file or assembly 'Newtonsoft.Json, Version=, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed' or one of its dependencies. The system cannot find the file specified.” Or how about this one? “System.IO.FileLoadException : Could not load file or assembly 'Moq, Version=3.1.416.3, Culture=neutral, PublicKeyToken=69f491c39445e920' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

Search all you want, most things you find on the Internet are from the pre-NuGet era and don’t really help. What now? In this post, let’s go over why this error sometimes happens. And I’ll end with a beautiful little trick that fixes this issue when you encounter it. Let’s go!

Redirecting Assembly Versions

In 90% of the cases, the errors mentioned earlier are caused by faulty assembly redirects. What are those, you ask? A long answer is on MSDN, a short answer is that assembly redirects let us trick .NET into believing that assembly A is actually assembly B. Or in other words, we can tell .NET to work with Newtonsoft.Json whenever any other reference requires an older version of Newtonsoft.Json.

Assembly redirects are often created by NuGet, to solve versioning issues. Here’s an example which I took from an application’s Web.config:


Code highlighting produced by Actipro CodeHighlighter (freeware)

--><?xml version="1.0" encoding="utf-8"?>
<!-- ... -->
<legacyHMACWarning enabled="0" />
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" culture="neutral" />
<bindingRedirect oldVersion="" newVersion="" />
<!-- Code inserted with Steve Dunn's Windows Live Writer Code Formatter Plugin. -->

When running an application with this config file, it will trick any assembly that wants to use any version < of Newtonsoft.Json into working with the latest version. Neat, as it solves dependency hell where two assemblies require a different version of a common assembly dependency. But… does it solve that?

NuGet and Assembly Redirects

The cool thing about NuGet is that it auto-detects whenever assembly redirects are needed, and adds them to the Web.config or App.config file of your project. However, this not always works well. Sometimes, old binding redirects are not removed. Sometimes, none are added at all. Resulting in fine errors like the ones I opened this post with. At compile time. Or worse! When running the application.

One way of solving this is manually checking all binding redirects in all configuration files you have in your project, checking assembly versions and so on. But here comes the trick: we can let NuGet do this for us!

All we have to do is this:

  1. From any .config file, remove the <assemblyBinding> element and its child elements. In other words: strip your app from assembly binding redirects.
  2. Open the Package Manager Console in Visual Studio. This can be done from the View | Other Windows | Package Manager Console menu.
  3. Type this one, magical command that solves it all: Get-Project -All | Add-BindingRedirect. I repeat: Get-Project -All | Add-BindingRedirect

NuGet Add Binding Redirect

NuGet will get all projects and for every project, add the correct assembly binding redirects again. Compile, run, and continue your day without rage. Enjoy!

PS: For the other cases where this trick does not help, check Damir Dobric’s post on troubleshooting NuGet references.

Wednesday, September 10, 2014  |  From Maarten Balliauw {blog}

Many developers prefer to strong name sign their assemblies. The reason for this is to establish trust with the consumers of their applications: the signature proves that the code was built by the person who claims to be the author, and can be verified using a certificate. Signing code also means that the dependencies that are consumed must be signed. Not all third-party dependencies are signed, though, for example when consuming packages from NuGet. Some are signed, some are unsigned, and the only way to know is when at compile time when we see this:

Referenced assembly does not have a strong name

That’s right: a signed assembly cannot consume an unsigned one. Now what if we really need that dependency but don’t want to lose the fact that we can easily update it usign NuGet… Turns out there is a NuGet package for that!

The Assembly Strong Naming Toolkit can be installed into our project, after which we can use the NuGet Package Manager Console to sign referenced assemblies. There is also the .NET Assembly Strong-Name Signer by Werner van Deventer, which provides us with a nice UI as well.

The problem is that the above tools only sign the assemblies once we already consumed the NuGet package. With package restore enabled, that’s pretty annoying as the assemblies will be restored when we don’t have them on our system, thus restoring unsigned assemblies…

NuGet Signature

Based on the .NET Assembly Strong-Name Signer, I decided to create a small utility that can sign all assemblies in a NuGet package and creates a new package out of those. This “signed package” can then be used instead of the original, making sure we can simply consume the package in Visual Studio and be done with it. Here’s some sample code which signs the package “MyPackage” and creates “MyPackage.Signed”:


Code highlighting produced by Actipro CodeHighlighter (freeware)

-->var signer = new PackageSigner();
"SampleKey.pfx", "password",
<!-- Code inserted with Steve Dunn's Windows Live Writer Code Formatter Plugin. -->

This is pretty neat, if I may say so, but still requires manual intervention for the packages we consume. Unless the NuGet feed we’re consuming could sign the assemblies in the packages for us?

NuGet Signature meets MyGet Webhooks

Earlier this week, MyGet announced their webhooks feature. After enabling the feature on our feed, we could pipe events, such as “package added”, into software of our own and perform an action based on this event. Such as, signing a package.

MyGet automatically sign NuGet package

Sweet! From the GitHub repository here, download the Web API project and deploy it to Microsoft Azure Websites. I wrote the Web API project with some configuration options, which we can either specify before deploying or through the management dashboard. The application needs these:

  • Signature:KeyFile - path to the PFX file to use when signing (defaults to a sample key file)
  • Signature:KeyFilePassword - private key/password for using the PFX file
  • Signature:PackageIdSuffix - suffix for signed package id's. Can be empty or something like ".Signed"
  • Signature:NuGetFeedUrl - NuGet feed to push signed packages to
  • Signature:NuGetFeedApiKey - API key for pushing packages to the above feed

The configuration in the Microsoft Azure Management Dashboard could look like the this:

Azure Websites

Once that runs, we can configure the web hook on the MyGet side. Be sure to add an HTTP POST hook that posts to <url to your deployed app>/api/sign, and only with the package added event.

MyGet Webhook configuration

From now on, all packages that are added to our feed will be signed when the webhook is triggered. Here’s an example where I pushed several packages to the feed and the NuGet Signature application signed the packages themselves.

NuGet list signed packages

The nice thing is in Visual Studio we can now consume the “.Signed” packages and no longer have to worry about strong name signing.

Thanks to Werner for the .NET Assembly Strong-Name Signer I was able to base this on.


 Maarten Balliauw {blog} News Feed 

Last edited Oct 15, 2008 at 8:15 AM by maartenba, version 4