Question

Describe the role of the IConfiguration interface in .NET Core and provide examples of how to read configuration values from different sources.

Answer 1

The IConfiguration interface in .NET Core plays a crucial role in managing application settings and configurations. It provides a unified API to access configuration data from various sources, such as JSON files, environment variables, or command-line arguments.

To read configuration values, first install the required NuGet packages for the desired configuration providers (e.g., Microsoft.Extensions.Configuration.Json). Then, create a ConfigurationBuilder instance, add the necessary providers, and build the configuration object.

Example using appsettings.json:

var builder = new ConfigurationBuilder()

.SetBasePath(Directory.GetCurrentDirectory())

.AddJsonFile("appsettings.json");

IConfiguration configuration = builder.Build();

string value = configuration["MySetting"];

Example using environment variables:

var builder = new ConfigurationBuilder().AddEnvironmentVariables();

IConfiguration configuration = builder.Build();

string value = configuration["MY_ENVIRONMENT_VARIABLE"];

Example using command-line arguments:

string[] args = { "--mysetting=value" };

var builder = new ConfigurationBuilder().AddCommandLine(args);

IConfiguration configuration = builder.Build();

string value = configuration["mysetting"];