I am writing this blog post because I often see a configuration support proposal that uses hardcoded strings. Here’s a way to avoid it.

My way

This is a sample appsettings.json file:

{
    "ExampleConfig": {
        "ValueA": "aaa",
        "ValueB": "https://example.com",
        "ValueC": 1234
    }
}

This is our example model which we want to load from the configuration:

public class ExampleConfig
{
    public string ValueA { get; set; }
    public Uri ValueB { get; set; }
    public int ValueC { get; set; }
}

Here’s how I read the model from the configuration:

public class ExampleCommandHandler
{
    private readonly IConfiguration _configuration;

    public ExampleClass(IConfiguration configuration)
    {
        _configuration = configuration;
    }

    public Task Handle(ExampleCommand)
    {
        var exampleConfig = _configuration
            .GetSection(nameof(ExampleConfig))
            .Get<ExampleConfig>()
            ?? throw new ConfigurationException(nameof(ExampleConfig));

        // ...
    }
}

There is one thing you need to watch out for. To call the Get<T> method, use Microsoft.Extensions.Configuration.Binder NuGet package.

That’s it. No hardcoded strings in the code!