.Net Core : Class Library to connect to DB, DAL, User Secret and Asp.Net Core's Configuration - asp.net-core

Question

I have the following :
a class library with connection classes such as connection, command, parameter
a DAL with entities, mapper, interface, services as well as a static class that holds hard coded connectionString and InvariantName.
an Asp.Net Core project
References :
DAL has a reference to the class library to make use of its connection class to which it provides connectionString and InvariantName thanks to its static class etc..
Asp.Net has a reference to the DAL.
What I want :
I now want to use the User Secrets to store hard coded sensitive data connections and get rid off the static class.
I know I can use the the Asp.Net Core startup.cs to read the settings from Configuration and make use of binding to store them into a class and use DI.
My guess :
DI seems "easy" when used inside an Asp controller. But I need the settings values (connectionString and InvariantName) outside the Asp.Net Core to be injected into a constructor of a class somewhere in my DAL.
I guess I would then need to have to reference the Asp.Net Core project to my DAL. But then I would end up with a circular reference (DAL to Asp.Net Core and the opposite).
So what's the solution?
Have an intermediate library class into which I would retreive the settings values from Asp.Net Core and then pass them to my DAL (to prevent circular reference)?
Manually recreate the "Configuration process" inside the DAL and get settings there directly
Or something else that I don't know?
Ps : I am new in development and only have a few projects'experience in Asp.Net Framework so far..and it's my first Asp.Net Core project

Answer 1

I know I can use the the Asp.Net Core startup.cs to read the settings from Configuration and make use of binding to store them into a class and use DI
You already answered your own question with this. This is the correct and recommended behavior to setup DI for 3rd party libs and configurations. If you want to avoid clutter in Startup class, create an extension method:
namespace Microsoft.Extensions.DependencyInjetion
{
public static MyLibraryCollectionExtensions
{
public static IServiceCollection AddMyLibrary(this IServiceCollection services)
{
services.AddDbContext<MyDbContext>(...);
}
}
}
to register your classes. Alternatively, extend the method to accept a parameter delegate to configure it
namespace Microsoft.Extensions.DependencyInjetion
{
public static MyLibraryCollectionExtensions
{
public static IServiceCollection AddMyLibrary(this IServiceCollection services, Action<MyOptions> setup)
{
var defaultOptions = ... // i.e. new MyOptions();
// pass default options to be modified by the delegate
setup?.Invoke(defaultOptions);
// your registrations
services.AddDbContext<MyDbContext>(...);
}
}
}
And all the user has to do in your library is add
services.AddMyLibrary();
// or with setup
services.AddMyLibrary(config =>
{
config.MyConnectionString = Configuration.GetConnectionString("MyContext");
});
and store the connection string in the appsettings.json.
{
"ConnectionStrings":
{
"MyContext" : "MyConnectionString here"
}
}

Answer 2

I finally used the ConfigurationBuilder to get values from the appsettings.json file.
It's probably not the right way to do it but it is working with my DAL and Connection dlls.
In case it helps anyone else :