.net 5 appsettings.json code example

Example 1: use appsettings.json in console app

All that’s required is to add the following NuGet packages and an appsettings.json file.

Microsoft.Extensions.Configuration
Microsoft.Extensions.Configuration.FileExtensions
Microsoft.Extensions.Configuration.Json

The appsettings.json files “Copy to Output Directory” property should also be set to “Copy if newer” so that the application is able to access it when published.

Example 2: .net using appsettings variables

var connectionString = ConfigurationManager.ConnectionStrings["Default"].ConnectionString;
connectionString.Expand() // returns "server=db01.mycompany.com;uid=uid;pwd=pwd;Initial Catalog=master;"

Example 3: .net using appsettings variables

<configuration>
    <appSettings>
        <add key="Domain" value="mycompany.com"/>
        <add key="ServerName" value="db01.{Domain}"/>
    </appSettings>
    <connectionStrings>
        <add name="Default" connectionString="server={ServerName};uid=uid;pwd=pwd;Initial Catalog=master;" provider="System.Data.SqlClient" />
    </connectionStrings>
</configuration>

Example 4: .net core read appsettings.json console app

class Program
{
    public static IConfigurationRoot configuration;

    static int Main(string[] args)
    {
        // Initialize serilog logger
        Log.Logger = new LoggerConfiguration()
             .WriteTo.Console(Serilog.Events.LogEventLevel.Debug)
             .MinimumLevel.Debug()
             .Enrich.FromLogContext()
             .CreateLogger();

        try
        {
            // Start!
            MainAsync(args).Wait();
            return 0;
        }
        catch
        {
            return 1;
        }
    }

    static async Task MainAsync(string[] args)
    {
        // Create service collection
        Log.Information("Creating service collection");
        ServiceCollection serviceCollection = new ServiceCollection();
        ConfigureServices(serviceCollection);

        // Create service provider
        Log.Information("Building service provider");
        IServiceProvider serviceProvider = serviceCollection.BuildServiceProvider();

        // Print connection string to demonstrate configuration object is populated
        Console.WriteLine(configuration.GetConnectionString("DataConnection"));

        try
        {
            Log.Information("Starting service");
            await serviceProvider.GetService<App>().Run();
            Log.Information("Ending service");
        }
        catch (Exception ex)
        {
            Log.Fatal(ex, "Error running service");
            throw ex;
        }
        finally
        {
            Log.CloseAndFlush();
        }
    }

    private static void ConfigureServices(IServiceCollection serviceCollection)
    {
        // Add logging
        serviceCollection.AddSingleton(LoggerFactory.Create(builder =>
        {
            builder
                .AddSerilog(dispose: true);
        }));

        serviceCollection.AddLogging();

        // Build configuration
        configuration = new ConfigurationBuilder()
            .SetBasePath(Directory.GetParent(AppContext.BaseDirectory).FullName)
            .AddJsonFile("appsettings.json", false)
            .Build();

        // Add access to generic IConfigurationRoot
        serviceCollection.AddSingleton<IConfigurationRoot>(configuration);

        // Add app
        serviceCollection.AddTransient<App>();
    }
}