Config files in .NET Core 2.2

.NET Core console application

This doesn’t use a dep injector. KISS (Keep It Simple S…): stackoverflow.com/a/46437144

Install NuGet package: Microsoft.Extensions.Configuration.Json

Program.cs

static void Main(string[] args)
{
    var builder = new ConfigurationBuilder()
        .SetBasePath(Directory.GetCurrentDirectory())
        .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true);

    IConfigurationRoot configuration = builder.Build();

    foreach(var repo in configuration.GetSection("repositories").GetChildren())
    {
        string projectName = repo["projectName"];
        string repositoryId = repo["repositoryId"];
    }
}

Example appsettings.json

Ensure this files properties are set to: “Copy to Output Directory” aka <CopyToOutputDirectory>

"repositories": [
  {
    "projectName": "repo0",
    "repositoryId": "b1821e2e-94c5-4cf0-824c-41d41966207e"
  },
  {
    "projectName": "repo1",
    "repositoryId": "2f6145f9-3472-441d-bb8e-0271b4d82e28"
  },
  {
    "projectName": "repo2",
    "repositoryId": "2b029778-281f-4bb6-82fc-961dfa0f0ad0"
  }
]

See real example: Salsa/Program.cs

ASP.NET Core projects

Dep injection of config: aspnet/core/fundamentals/configuration

Startup.cs

public Startup(IConfiguration configuration)
{
    Configuration = configuration;
}

public IConfiguration Configuration { get; }

public void ConfigureServices(IServiceCollection services)
{
    ...

    services.Configure<MyProject.Models.AppSettings>(Configuration.GetSection("MySection"));
}

Example appsettings.json

{
  "MySection": {
    "ApiUrl": "http://api.myapp.mydomain.org",
    "ApiVersion": 2
  }
}

AppSettings.cs

public class AppSettings
{
    public string ApiUrl { get; set; }
    public int ApiVersion { get; set; }
}

Controller.cs

public class MyController : Controller
{
    private readonly AppSettings _appSettings;

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

    public IActionResult Index()
    {
        string apiUrl = _appSettings.ApiUrl;
        return View();
    }
}

See real example: Core/Startup.cs

Single string

If you are just accessing a few things in the Startup.cs such as adding auth you can use the following to retrieve one string:

Configuration.GetValue<string>("Authority");

{
  "Authority": "https://youridentityserver3instance.com/identity"
}

Nested single string

If you want to retrieve a nested single string you can do the following. Notice how here we are using a index style access [] instead of the GetValue or GetSection methods. This is yet another way to retrieve config strings. If you used XML Web.config in .NET Framework this will be more familiar.

Configuration["ConnectionStrings:MyDatabase"];

{
  "ConnectionStrings": {
    "MyDatabase": "Data Source=localhost;Initial Catalog=MyDatabase;Integrated Security=True"
  }
}

Note worthy stuff

Use camelCase to conform to JSON standards but it seems MS cant decide if they want to stick to their old school PascalCase days.

Update: They seem to mostly give camelCase example code snippets now. Originally they had PascalCase JSON property names in the scaffolding templates.

• Call it: appsettings.json
• Untested example migration from web.config: stackoverflow.com/a/52341105 I say untested because I believe I did try this and it didn’t work however I didn’t spend much time at all testing maybe 5 mins.