Question

I’m trying to load modules into my application dynamically, but I want to specify separate app.config files for each one.

Say I have following app.config setting for main app:

<appSettings>
  <add key="House" value="Stark"/>
  <add key="Motto" value="Winter is coming."/>
</appSettings>

And another for library that I load using Assembly.LoadFrom:

<appSettings>
  <add key="House" value="Lannister"/>
  <add key="Motto" value="Hear me roar!"/>
</appSettings>

Both libraries have a class implementing the same interface, with the following method:

public string Name
{
    get { return ConfigurationManager.AppSettings["House"]; }
}

And sure enough calls to Name from both main class and loaded assembly class output Stark.

Is there a way to make main app use its own app.config and each loaded assembly use theirs? Names of config files are different in the output, so that should be possible I think.

Answer 1

Ok, here’s the simple solution I ended up with:
Create the follow function in the utility library:

public static Configuration LoadConfig()
{
    Assembly currentAssembly = Assembly.GetCallingAssembly();
    return ConfigurationManager.OpenExeConfiguration(currentAssembly.Location);
}

Using it in dynamically loaded libraries like this:

private static readonly Configuration Config = ConfigHelpers.LoadConfig();

No matter how that library gets loaded it uses the correct config file.

Edit:
This might be the better solution for loading files into ASP.NET applications:

public static Configuration LoadConfig()
{
    Assembly currentAssembly = Assembly.GetCallingAssembly();
    string configPath = new Uri(currentAssembly.CodeBase).LocalPath;
    return ConfigurationManager.OpenExeConfiguration(configPath);
}

To copy file after build you might want to add the following line to post-build events for asp app (pulling the config from library):

copy "$(SolutionDir)<YourLibProjectName>\$(OutDir)$(Configuration)\<YourLibProjectName>.dll.config" "$(ProjectDir)$(OutDir)"