The Endless Obsession

better code

.NET: Getting the Project Root Directory at Runtime

When developing in .NET, whether it be an ASP.NET website, or a console application, you usually don’t have to access the file-system directly. One reason that you would is to read a configuration file, but, .NET configuration management handles this for you via ‘Web.config’ or ‘App.config’ and the ConfigurationManager. Another scenario is loading a resource, like an image or document, from disk. But, again, the framework provides a nice solution via embedded resources.

If you’re considering accessing the file-system you would do well to consider if there are better ways to do what you’re trying to do. That being said, you may occasionally have a legitimate reason to access the file-system directly.

Here are a few simple examples of how to do this:

ASP.NET

var root = HttpContext.Current.Server.MapPath("~/");

WinForms

var root = Application.ExecutablePath;

WPF, Console Application, etc.

var assembly = System.Reflection.Assembly.GetEntryAssembly();
var assemblyPath = new Uri(assembly.CodeBase).AbsolutePath;
var root = System.IO.Path.GetDirectoryName(assemblyPath);

So, why would you even want to do this?

Dev-Mode Overrides

The most useful example that comes to mind for me is overriding behavior in a development setting.

A few reasons that I’ve personally encountered…

  1. Avoid merge conflicts by keeping branch-specific config out of source control
  2. Avoid password leaking by keeping sensitive config out of source control
  3. Facilitate local testing via a “developer mode” triggered by a local file
  4. Track unit test data in source control and access files from tests

Merge conflicts are no fun. If you’re working in different branches you don’t want to have to hand-edit files when merging just because a file path, database name, website name, etc. varies by branch. Keep that stuff in non-tracked files.

It’s hard to keep passwords out of source control. Making it easy to provide them via files that are not tracked in source control is one way you could try to prevent that problem. A secure credential store of some kind would be even better, but ya know, KISS.

In some cases, real-world testing is hard, or nearly impossible. The presence of a local file is one way you could switch into a dev mode in order to simulate real-world conditions. Of course, just to be safe, you’ll probably want to toggle that based on ‘Debug’ mode or a custom build flag as well.

If your unit tests require some data to run, like the kind of stuff you might find in a database, you may want to consider source controlled files instead. This gives you the benefit of portability, the test data comes with the source code. Also, you can track changes over time if it’s in a human-readable format.

Bringing it Home

With that in mind, here’s an example of code that you can use to find the root directory of your project from your running application.

References:

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