How can I replace config file database links in one place in source code? (asp.net/razor) - asp.net-mvc-3

Question

I have an ASP.NET/Razor 3 web application which uses a SQL Server database via MS EntityFramework.
If/when I want to change the database connection string, for example to change the password or point to a different database (e.g. test vs. live), the string needs to replaced in about seven places in three different XML config files in the project (app.config, web.config, and app.release.config), which is an error-prone pain.
Worse, the default web server behavior on unhandled exceptions can include displaying sections of the config files to web users, which has in fact resulted in the web server displaying the lines that show the database path and password over the web. Not good.
For both reasons, and because this is not a product for which anyone would ever just edit the config file on the server (any change is pretty much, and may as well be, a build operation), I would much prefer to have the database connection information compiled into the web application and loaded from code rather than a config file, and to be able to do this such that when I want to change the database information, I can do it in one place instead of seven.
How would I achieve this?

Answer 1

The database connection string(s) can be set up centrally in 1 place, in the Global.asax.cs file, as part of the Application State, and then referenced from anywhere else in the project.
Step-1: Define the connection string(s) as static variables in Global.asax.cs:
namespace TestProject
{
// Note: For instructions on enabling IIS6 or IIS7 classic mode,
// visit http://go.microsoft.com/?LinkId=9394801
public class MvcApplication : System.Web.HttpApplication
{
public static string ConnectionString1;
public static string ConnectionString2;
protected void Application_Start()
{
#region Build application state for the app-specific items needed by us
ConnectionString1 = "Server=yourserver;Database=yourdb;etc etc";
ConnectionString2 = "Server=yourserver;Database=yourdb;etc etc";
#endregion
#region Code auto-generated and needed by system - do not change
AreaRegistration.RegisterAllAreas();
WebApiConfig.Register(GlobalConfiguration.Configuration);
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
RouteConfig.RegisterRoutes(RouteTable.Routes);
BundleConfig.RegisterBundles(BundleTable.Bundles);
AuthConfig.RegisterAuth();
#endregion
}
}
}
Step-2: Use the strings from anywhere else in the project:
string cnxStr1 = TestProject.MvcApplication.ConnectionString1;
string cnxStr2 = TestProject.MvcApplication.ConnectionString2;
(Please note that by default, the strings would be accessible only from within the same project. You will need to add references to the project if you need to use the strings from any other project within the same solution.)

Answer 2

The answer above by Krishna is pretty good. For me I would personally prefer to have them as static string in a static class and use it where ever is needed.

Answer 3

If you don't want to put the connection strings in the global file, you can:
Create a separate .config file for connection strings. e.g.
connectionStrings.config.
Create a hard-link to this file or the
folder containing this file that's in the same directory as your
other application.config and web.config files.
Set the configSource property on the connectionStrings element in each app.config or
web.config.
From then on, you only have one place to manage your connection strings that are common between apps.
The reason for the hard link is that configSource must reference a file in the same folder or sub-folder of the folder containing the application config.
Note that changing the connection strings will recycle all your web application pools that use them. For console, desktop, and service apps, you will have to restart for changes to take effect.
For the second problem you describe, you could have a separate connectionStrings.config file for each environment: development, test, production. Using config transforms or some other process, you only have to update the configSource property in each connectionString element to switch environments.