C# – Why are application settings read-only in app.config

Any configuration that might differ across environments should be stored at the machine level, not the application level. (More info on configuration levels.)

These are the kinds of configuration elements that I typically store at the machine level:

• Application settings
• Connection strings
• retail=true
• Smtp settings
• Health monitoring
• Hosting environment
• Machine key

When each environment (developer, integration, test, stage, live) has its own unique settings in the c:\Windows\Microsoft.NET\Framework64\v2.0.50727\CONFIG directory, then you can promote your application code between environments without any post-build modifications.

And obviously, the contents of the machine-level CONFIG directory get version-controlled in a different repository or a different folder structure from your app. You can make your .config files more source-control friendly through intelligent use of configSource.

I've been doing this for 7 years, on over 200 ASP.NET applications at 25+ different companies. (Not trying to brag, just want to let you know that I've never seen a situation where this approach doesn't work.)

As per Prerak K's update comment (since deleted):

I guess I have not presented the question properly.

Situation is this: I want to load data into a global variable based on the value of a control. I don't want to change the value of a control from the child thread. I'm not going to do it ever from a child thread.

So only accessing the value so that corresponding data can be fetched from the database.

The solution you want then should look like:

UserContrl1_LOadDataMethod()
{
    string name = "";
    if(textbox1.InvokeRequired)
    {
        textbox1.Invoke(new MethodInvoker(delegate { name = textbox1.text; }));
    }
    if(name == "MyName")
    {
        // do whatever
    }
}

Do your serious processing in the separate thread before you attempt to switch back to the control's thread. For example:

UserContrl1_LOadDataMethod()
{
    if(textbox1.text=="MyName") //<<======Now it wont give exception**
    {
        //Load data correspondin to "MyName"
        //Populate a globale variable List<string> which will be
        //bound to grid at some later stage
        if(InvokeRequired)
        {
            // after we've done all the processing, 
            this.Invoke(new MethodInvoker(delegate {
                // load the control with the appropriate data
            }));
            return;
        }
    }
}