AppSettings - Six Ways To Read The Config In ASP.NET CORE 3.0

public sealed class MySettingsConfiguration  
{  
    public bool Log { get; set; }  
    public string ConnectionStringId { get; set; }  
    public Parameters Parameters { get; set; }  
}  

public sealed class Parameters  
{  
    public bool IsProduction { get; set; }  
}

Now it’s just to configure the binding between a MySettingsConfiguration instance and the configuration section using the Bind method, check it out.

[ApiController]
[Route("[controller]")]
public class Way4Controller : ControllerBase
{
    private readonly MySettingsConfiguration _settings;
   
    public Way4Controller(IConfiguration configuration)
    {
        _settings = new MySettingsConfiguration();
        configuration.GetSection("MySettings").Bind(_settings);
    }
   
    [HttpGet]
    public bool Get()
    {
        return _settings?.Parameters?.IsProduction ?? false;
    }
}

But we are still using the GetSection method, dependency injection of IConfiguration in the controller’s constructor. We can do better than that!

5. AppSettings IOptions

The next way to read the AppSettings.JSON file is by using the IOptions interface by typing the MySettingsConfiguration class that we created before.

[ApiController]
[Route("[controller]")]
public class Way5Controller : ControllerBase
{
    private readonly IOptions<MySettingsConfiguration> _configuration;
   
    public Way5Controller(
        IOptions<MySettingsConfiguration> configuration)
    {
        _configuration = configuration;
    }
   
    [HttpGet]
    public bool Get()
    {
        return _configuration.Value?.Parameters?.IsProduction ?? false;
    }
}

Remember, to use it that way it’s necessary to perform a small configuration on the Startup.cs file.

public void ConfigureServices(IServiceCollection services)
{
    // Way 5
    services.Configure<MySettingsConfiguration>(Configuration.GetSection("MySettings"));
    
    services.AddControllers();
}

That is a better way to read the AppSettings.JSON file, but we are still using an ASP.NET CORE internal interface, in this case, the IOptions interface.

It could be interesting that all controllers and business classes don’t use ASP.NET CORE internal references.

6. AppSettings PRE-Binding

In my opinion, the best way to read the AppSettings.JSON file is to inject the MySettingsConfiguration class that we created before.

[ApiController]
[Route("[controller]")]
public class Way6Controller : ControllerBase
{
    private readonly MySettingsConfiguration _configuration;
    
    public Way6Controller(MySettingsConfiguration configuration)
    {
        _configuration = configuration;
    }
    
    [HttpGet]
    public bool Get()
    {
        return _configuration.Parameters.IsProduction;
    }
}

This way is much more straightforward, and we don’t use any ASP.NET CORE internal interface.

To make this work, it’s necessary one configuration is in the Startup.cs file.

public void ConfigureServices(IServiceCollection services)
{
    // Way 6
    var mySettings = new MySettingsConfiguration();
    new ConfigureFromConfigurationOptions<MySettingsConfiguration>(Configuration.GetSection("MySettings")).Configure(mySettings);
    services.AddSingleton(mySettings);

    services.AddControllers();
}

That configuration seems too complex to understand, even more, if you need to repeat that code for other tags and classes.

To make it easy and not repeat any code, I created an Extension Method to encapsulate all these code blocks, and it becomes very easy to use it.

public void ConfigureServices(IServiceCollection services)
{
    // Way 6 extension
    services.AddConfiguration<MySettingsConfiguration>(Configuration, "MySettings");

    services.AddControllers();
}

public static class ConfigurationExtension
{
    public static void AddConfiguration<T>(
        this IServiceCollection services,
        IConfiguration configuration,
        string configurationTag = null)
        where T : class
    {
        if (string.IsNullOrEmpty(configurationTag))
        {
            configurationTag = typeof(T).Name;
        }

        var instance = Activator.CreateInstance<T>();
        new ConfigureFromConfigurationOptions<T>(configuration.GetSection(configurationTag)).Configure(instance);
        services.AddSingleton(instance);
    }
}

That’s it, thank you for reading, and I hope you enjoyed it.

Share and comment if you know other ways to read settings in the AppSettings.JSON file.

Thank you