Getting the |DataDirectory| folder in C sharp

One of the cool things about sql server express’s connection strings is the ability to relatively path database files for sql express databases. Often one might see something in the connection string that looks like ” AttachDbFilename=|DataDirectory|\file.mdf “. The pipes and DataDirectory is parsed to equate to a relative data directory file path that changes depending on the application type (i.e. an application deployed by click once, vs an application that is installed to a folder).

However sometimes you might want to know where that data directory is, like in my case, I want to take a look at a connection string and attempt to create a database based off the connection string in order to speed up development using database migrations. This could also come in handy deploying small applications.

So after some research via google, I found this gem on msdn about where the DataDirectory is, though not guaranteed to be accurate. It basically follows 3 simple hierarchal rules. If the AppDomain.SetData method has been used, then the directory is set there. Otherwise if the application is a click once application the data directory is set or its in the application root folder.

So below is what the code might possibly look like in order to get the applications data directory no matter what type of application it is and it gives you ability to set the DataDirectory as well.

namespace Amplify
{
 using System;
 using System.Configuration;
 using System.Collections.Generic;
 using System.Collections.Specialized;
 using System.Deployment;
 using System.Deployment.Application;
 using System.IO;
 using System.Text;
 using System.Reflection;
 using System.Web;

 public class ApplicationContext {

  private static NameValueContext s_properties;

  public static bool IsWebsite { get; internal set; }

  static ApplicationContext()
  {
   IsWebsite = (System.Web.HttpContext.Current != null);

  }

  public static string DataDirectory
  {
   get
   {
    string dataDirectory = GetProperty("DataDirectory") as string;

    if (string.IsNullOrEmpty(dataDirectory))
    {
     dataDirectory = AppDomain
      .CurrentDomain.GetData("DataDirectory") as string;

     if (dataDirectory == null)
     {
      if (ApplicationDeployment.IsNetworkDeployed)
       dataDirectory = ApplicationDeployment
        .CurrentDeployment.DataDirectory;
      else
       dataDirectory = Path.GetDirectoryName(
        Assembly.GetExecutingAssembly()
         .GetName().CodeBase);
     }
     dataDirectory = dataDirectory.Replace(@"file:\", "");
     SetProperty("DataDirectory", dataDirectory);
    }
    return dataDirectory;
   }
   set
   {
    string dataDirectory = GetProperty("DataDirectory") as string;
    value = value.Replace(@"file:\", value);

    if (!System.IO.Directory.Exists(dataDirectory))
     System.IO.Directory.CreateDirectory(dataDirectory);

    SetProperty("DataDirectory", value);
    AppDomain.CurrentDomain.SetData("DataDirectory", value);
   }
  }

  public static object GetProperty(string propertyName)
  {
   if (IsWebsite)
    return HttpContext.Current.Application[propertyName];
   else
    return Context[propertyName];
  }

  public static void SetProperty(string propertyName, object value)
  {
   if (IsWebsite)
    HttpContext.Current.Application[propertyName] = value;
   else
    Context[propertyName] = value;
  }

  private static NameValueContext Context
  {
   get
   {
    if (s_properties == null)
     s_properties = new NameValueContext();
    return s_properties;
   }
  }
 }
}