How to programmatically override web.config settings

Question

When I have a specific setting in web.config, say the session state configuration, and I want to programmatically determine the configuration at Application_Start, how would I go about this. I am trying to have a slightly different configuration per environment.

I do not want to overwrite the real web.config (prevent restarts)
I know the solution presented in Use XML includes or config references in app.config to include other config files' settings, but I don't want the whole system.web section in a separate file, and system.web does not implement a file attribute like appSettings and connectionStrings do.

Any ideas?

you don't wanna get any extra rep point --> 666 – JohnIdol Oct 15 '09 at 16:26 — JohnIdol, Oct 15 '09 at 16:26

score 3 · Accepted Answer · answered Oct 15 '09 at 16:44

I don't think that you can alter settings from the web.config at runtime without it reloading the application. As the article in @ChristopheD's answer shows, you can read and write web.config settings at runtime, but saving them restarts the application when it writes out the changes. I'm pretty sure that once your app gets to the point where you can do this ASP.NET has already read them in and changing them at runtime without saving them will have no effect.

FWIW, I'd recommend against this type of environment-specific manipulation at runtime. A better approach is to alter the web.config per environment at build or deployment time. MSDeploy has a way to do this, and that functionality is coming to VS2010.

Correct, for the config changes to take effect one must restart AppDomain. In case of ASP.NET that means restart of your application with all the consequences (loosing cache content, all user sessions for in-memory session, etc). — UserControl, Oct 16 '09 at 10:54
Thanks; clear answer. Not what I hoped for, but I will have a better look at MSDeploy. — Teun D, Oct 19 '09 at 09:22

score 1 · Answer 2 · edited Nov 05 '14 at 18:03

1

The following link should be helpful...

PS: It's the first thing you find when you type 'alter web.config programmatically' into google.

edited Nov 05 '14 at 18:03

bmm6o

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answered Oct 15 '09 at 16:33

ChristopheD

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That sample shows how to change web.config. However, as stated in the question, I don't want to overwrite the file to prevent restarts. ASP.NET will not see any of the changes you make this way until you save the file. – Teun D Oct 19 '09 at 09:20

How to programmatically override web.config settings

2 Answers2

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