Feature Toggles

Feature toggles (also known as feature flags) let you enable or disable parts of your application at runtime, without deploying new code. Serenity provides a small abstraction (IFeatureToggles) and integrates it with configuration, type discovery, navigation, and MVC.

IFeatureToggles

The core abstraction is the IFeatureToggles interface:

public interface IFeatureToggles
{
    bool IsEnabled(string feature);
}

The default implementation, ConfigurationFeatureToggles, reads from the FeatureToggles section of the configuration. Unless a feature is explicitly set to "false", it is considered enabled:

{
  "FeatureToggles": {
    "DataAuditLog": false,
    "EmailQueue": true
  }
}

Registration

AddFeatureToggles() registers the IFeatureToggles service:

services.AddFeatureToggles(configuration);

In a typical Serene/StartSharp application you don't call it directly. The template calls AddApplicationPartsFeatureToggles(Configuration) in Startup.cs (see Initialization and Startup), which scans the application parts for feature key sets, applies defaults and dependencies, and registers the service:

services.AddApplicationPartsFeatureToggles(Configuration);

Defining Feature Keys

Features are usually defined as an enum marked with the FeatureKeySet attribute:

[FeatureKeySet]
public enum FeatureKeys
{
    [Description("Data Audit Log")]
    DataAuditLog,

    [Description("Email Queue")]
    EmailQueue,

    [DefaultValue(false)]
    DataExplorer
}

AddApplicationPartsFeatureToggles scans for such enums:

• Members marked with [DefaultValue(false)] are disabled by default (unless explicitly enabled in configuration).
• RequiresFeature attributes on the enum or its members declare dependencies: a feature is only enabled when all (or any, via RequireAny) of its dependencies are enabled.

Checking Features

Inject IFeatureToggles and call IsEnabled:

public class SomeService(IFeatureToggles featureToggles)
{
    public void DoSomething()
    {
        if (featureToggles.IsEnabled(FeatureKeys.DataExplorer))
        {
            // ...
        }
    }
}

The FeatureTogglesExtensions class provides overloads that accept enum values directly, or sets of features (requiring all or any of them).

Restricting Pages and Actions

The FeatureBarrierAttribute (in Serenity.Net.Web) can be placed on MVC controllers, actions, or Razor pages. When a required feature is disabled, the action/page is not accessible (returns 404):

[FeatureBarrier(FeatureKeys.DataExplorer)]
public class DataExplorerPage : Controller
{
    // ...
}

Filtering by the Type Source

The type source itself respects feature toggles. BaseAssemblyTypeSource (which ApplicationPartsTypeSource derives from) excludes assemblies and types marked with [RequiresFeature] whose features are disabled. This means a disabled feature's types — including its navigation attributes, rows, and services — are not discovered at all, so their navigation links and other UI elements simply don't appear.

In other words, placing [RequiresFeature] or [FeatureBarrier] on a page/controller is usually enough to hide everything related to it.

See Also

• Initialization and Startup
• Configuration