How to access the app.config value in the class library?

Question

I have a web application which is using a dll of a class library. I am unable to access the app.config value in the class library

How I'm trying to access app.config:

ConfigurationSettings.AppSettings["conStr"].ToString();

this is returning a null value

Also when I try to use ConfigurationManager it says not found or missing assembly reference.

using System.Configuration is also added .

Answer 1

You must put the AppSettings value inside the web.config of the application, because it override the app.config from the class library.

Add a reference to System.Configuration namespace in the class library project, them get the value you're expecting from the web.config file, not from the app.config file.

Answer 2

Add a reference to the System.Configuration library in your project, then get your key like this

ConfigurationManager.AppSettings["conStr"]

Notice that a web application will search for a web.config file and not an app.config!