.NET Configuration

The configuration system depends on configuration providers - the sources of configuration data.

Options

services.Configure<MyOptions>(Configuration.GetSection("MyOptions"));

The IOptions<T> instance is registered as a singleton.

The class/record for our options needs to have properties that:

• are public
• have getters
• have setters (or non-null value if complex type)
• are not indexers

Lambda

We are able to customize Options in runtime:

services.Configure<MyOptions>(Configuration.GetSection("MyOptions"));
services.Configure<MyOptions>(options =>
{
    options.Mode = Modes.Mode1;
});

The configuration system executes both operations. First, the IConfiguration is read and then Mode property is overwritten.

Without Options

Nuget packages:

• Microsoft.Extensions.Configuration;
• Microsoft.Extensions.Configuration.Files.Json
• Microsoft.Extensions.Configuration.Binder

Building

private static AppConfiguration GetConfiguration()
{
    var rawConfig = new ConfigurationBuilder()
        .SetBasePath(Directory.GetCurrentDirectory())
        .AddJsonFile("appsettings.json")
        .Build();

    return ConfigurationBinder.Get<AppConfiguration>(rawConfig);
}

References

• Options pattern guidance for .NET library authors (MSDN)