c# - Passing application's connection string down to a Repository Class Library in ASP.NET 5 using the IConfigurationRoot

Question

I have an ASP.NET 5 MVC Web Application and in Startup.cs I see that the public property

IConfigurationRoot Configuration 

is being set to builder.Build();

Throughout the MVC Web Application I can simply do

Startup.Configuration["Data:DefaultConnection:ConnectionString"]

to get the conn string from the appsettings.json file.

How can I get the connection string specified in the ASP.NET 5 MVC appsettings.json passed down to my Repository Class Library using constructor injection?

UPDATE:
Here is the base repository that all other repositories inherit from (as you can see I have a hardcoded connection string in here for now):

public class BaseRepo
{
    public static string ConnectionString = "Server=MYSERVER;Database=MYDATABASE;Trusted_Connection=True;";

    public static SqlConnection GetOpenConnection()
    {
        var cs = ConnectionString;
        var connection = new SqlConnection(cs);
        connection.Open();
        return connection;
    }
}

In my asp.net 5 web application in my appsettings.json file I have the following which is equivalent to adding a connection string to a web.config in a .net 4.5 webapp:

  "Data": {
    "DefaultConnection": {
      "ConnectionString": "Server=MYSERVER;Database=MYDATABASE;Trusted_Connection=True;"
    }
  }

Additionally in my asp.net 5 web application I have the following default code in my Startup.cs which loads the sites configuration into a public property of type IConfigurationRoot:

 public IConfigurationRoot Configuration { get; set; }
// Class Constructor
        public Startup(IHostingEnvironment env)
        {
            // Set up configuration sources.
            var builder = new ConfigurationBuilder()
                .AddJsonFile("appsettings.json")
                .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true);

            if (env.IsDevelopment())
            {
                // For more details on using the user secret store see http://go.microsoft.com/fwlink/?LinkID=532709
                builder.AddUserSecrets();
            }

            builder.AddEnvironmentVariables();
            Configuration = builder.Build();
        }

Now in my asp.net web application if I would like to access any of the appsettings I can simple do the following: Startup.Configuration["Data:DefaultConnection:ConnectionString"]

But unfortunately I can't do this from my class library..

If someone wants to try and figure this out here are the steps to reproduce:

1. Create a new ASP.NET 5 MVC Web App.
2. Add another project of type Class Library (Package) to the project.
3. Figure out a way to pass appsettings from the ASP.NET 5 MVC App to the Class Library

After updating I still can't quite get it. Here is my code:

public class BaseRepo
{
    private readonly IConfigurationRoot config;

    public BaseRepo(IConfigurationRoot config)
    {
        this.config = config;
    }
}

This class declaration does not work since BaseRepo requires a constructor param now.

public class CustomerRepo : BaseRepository, ICustomerRepo
{
    public Customer Find(int id)
    {
        using (var connection = GetOpenConnection())
        {
            ...
        }
    }
}

Answer 1

on your Startup.cs file add the following method

public void ConfigureServices(IServiceCollection services) {
    services.AddSingleton(_ => Configuration);
}

then update your BaseRepo class like this

public class BaseRepo {
    private readonly IConfiguration config;

    public BaseRepo(IConfiguration config) {
        this.config = config;
    }

    public SqlConnection GetOpenConnection() {
        string cs = config["Data:DefaultConnection:ConnectionString"];
        SqlConnection connection = new SqlConnection(cs);
        connection.Open();
        return connection;
    }
}