How to access appsettings from another project

Question

In the startup file I need a way to access IConfiguration in another project. I have been told the Business Logic should not know about IConfiguration. If thats the case then how do I inject data from appsettings down to the business logic projects.

appsettings.json

{
  "AdminEmail": "[email protected]"
}

How would I access AdminEmail in a class library I created in the same solution?

Answer 1

• Define a model for settings

  public sealed class EmailSettings
  {
      public string AdminEmail { get; set; }
  }
  

• Configure settings

  public sealed class Startup
  {
      private readonly IConfiguration configuration;
  
      public Startup(IConfiguration configuration) => this.configuration = configuration;
  
      public void ConfigureServices(IServiceCollection services)
      {
          services
              .Configure<EmailSettings>(configuration)
              .AddSingleton(sp => sp.GetRequiredService<IOptions<EmailSettings>>().Value);
      }
  }
  

• Inject and use it

  public class ClassLibraryInTheSameSolution
  {
      public ClassLibraryInTheSameSolution(EmailSettings emailSettings)
      {                         
      }
  }
  

Answer 2

You could inject it quite easily:

public class EmailSettings
{
    public string AdminEmail { get; set; } // encapsulate as needed
}

public void ConfigureServices(IServiceCollection services)
{
    var settings = new EmailSettings
    {
        AdminEmail = Configuration["AdminEmail"]
    };

    services.AddSingleton(settings);
}

public class WhereverYouNeedThis
{
    private readonly EmailSettings _emailSettings;

    public WhereverYouNeedThis(EmailSettings emailSettings)
    {
        _emailSettings = emailSettings;
    }

    public void Use()
    {
        Debug.Log(_emailSettings.AdminEmail);
    }
}

Answer 3

You can use Microsoft.Extensions.Configuration to achieve this. https://docs.microsoft.com/en-us/aspnet/core/fundamentals/configuration/?tabs=basicconfiguration

1 - Create a model for the settings

public class AppSettings 
{
    public string AdminEmail { get; set; }
}

2 - Configure it on Startup.cs

services.Configure<AppSettings>(Configuration);

3 - Use DI in your class library to retrieve the settings

private readonly AppSettings _appSettings;

public MyClass(IOptions<AppSettings> appSettings)
{
    _appSettings = appSettings.Value;
}