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

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;
    }
}

ASP.NET provides its own way of passing around configuration settings.

Suppose you have the this in your appSettings.json:

{
  "Config": {
    "Setting1": 1,
    "Setting2": "SO"
  }
}

Then you need a class like this:

public class MyConfiguration
{
    public int Setting1 { get; set; }

    public string Setting2 { get; set; }
}

This allows you to configure your service with this configuration by adding the following line

services.Configure<MyConfigurationDto>(Configuration.GetSection("Config"));

to ConfigureServices.

You can then inject the configuration in constructors by doing the following:

public class SomeController : Controller
{
    private readonly IOptions<MyConfiguration> config;

    public ServiceLocatorController(IOptions<MyConfiguration> config)
    {
        this.config = config;
    }

    [HttpGet]
    public IActionResult Get()
    {
        return new HttpOkObjectResult(config.Value);
    }
}

This example is for controllers. But you can do the same with other layers of you application.

I have a constructor in my repository class that accepts the db connection string as a parameter. This works for me when I add my repository for injection. In ConfigureServies() of the startup.cs file add this:

services.AddScoped<IRepos>(c => new Repos(Configuration["DbConnections:ConnStr1"]));

IRepos.cs is the interface, Repos.cs is the class that implements it. And of course Configuration is just a reference to the built IConfigurationRoot object.