Dynamically change connectionString in web.config

Question

I have the following in my web.config

Answer 1

Even if it's a bad idea to modify the web.config file from inside an app, you can try this:

System.Configuration.ConfigurationManager.AppSettings.Set("keyToBeReplaced", "newKeyValue");

Answer 2

• It's a bad idea to modify a *.config file from inside the program.
• It's a bad idea for a webpage to modify any file in the root folder of your website.
• It's a bad idea to have permission set allowing a web page the modification of files in the root folder of your website.

Basically, you need to forget about the web.config, and structure your code to use a connection string the exist only in memory.

Answer 3

If a user is able to change the value of the Setting, then the web.config file is the wrong place to store the setting.

You should check out a User Scoped value in a Settings file instead.

MSDN - Using Settings in C#

When using settings like this, changing the value at runtime is easy:

Properties.Settings.Default.LdapConnectionString = "New Connection String";
Properties.Settings.Default.Save();

Answer 4

var settings = ConfigurationManager.ConnectionStrings[ 0 ];

var fi = typeof( ConfigurationElement ).GetField( "_bReadOnly", BindingFlags.Instance | BindingFlags.NonPublic );

fi.SetValue(settings, false);

settings.ConnectionString = "Data Source=Something";