Forcing Entity Framework and ASP.MVC to use the connection string from app.config of another assembly

Question

Set & settings:

I use Entity Framework 5 and have a dll project with edmx file. In this project I have App.config with connection string for the EF model. I have also second project, ASP.MVC 4 web application which is a startup project. It references the database project. Important thing is - db is Oracle and EF uses Oracle custom providers.

Problem:

If I place my connection string in the ASP.MVC startup project is works fine. It's common advice to do this. But I don't want to. I don't see reason why I should. How can I force MVC/EF to find the connection string in App.config of the external library (which as a matter of fact is a data access layer)?

Answer 1

App.Config is used by WinForms, WPF and executable applications.

Web.Config is used in IIS (and is able to set IIS environment specific configurations)

It seems no App.Config will ever be merged to the Web.Config ( source ):

In using an App.config, file the configuration system merges the App.config file with content of the Machine.config file when the application starts and the configuration is applied. This mechanism allows machine-wide settings to be defined in the Machine.config file. The App.config file can be used to override the settings of the Machine.config file; you can also lock in the settings in Machine.config file so that they get used. In the Web.config case , the configuration system merges the Web.config files in all directories leading up to the application directory into the configuration that gets applied. For more information about configuration and the setting priorities, see topics in the System.Configuration namespace.

Perhaps you'll find a solution more appropriate to your needs by using Application Configuration Files .

Answer 2

Finally, after facing multiple issues, I've decided to move connection string of DAL into the Web.config of the web application. I was convinced by some arguments you can read here in the post of Chris Ammerman.