Legacy .NET Server SDK

Setup the SDK

1. Install the SDK

   The package is hosted on Nuget. Install it through Visual Studio's Nuget package manager or through the NuGet CLI:

   bash

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   nuget install Statsig
   

2. Initialize the SDK

   After installation, initialize the SDK using a Server Secret Key from the Statsig console.

   Do NOT embed your Server Secret Key in client-side applications, or expose it in any external-facing documents. If you accidentally expose it, you can create a new one in the Statsig console.

   csharp

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   using Statsig;
   using Statsig.Server;
   
   await StatsigServer.Initialize(
       "server-secret-key",
       // optionally customize the SDKs configuration via StatsigOptions
       new StatsigOptions(
           environment: new StatsigEnvironment(EnvironmentTier.Development)
       )
   );
   

   initialize performs a network request. After initialize completes, virtually all SDK operations are synchronous (refer to Evaluating Feature Gates in the Statsig SDK). The SDK fetches updates from Statsig in the background, independently of API calls.

Working with the SDK

Checking a Feature Flag/Gate

var user = new StatsigUser { UserID = "some_user_id", Email = "user@email.com" };
var useNewFeature = await StatsigServer.CheckGate(user, "use_new_feature");
if (useNewFeature)
{
  // Gate is on, enable new feature
}
else
{
  // Gate is off
}

Reading a Dynamic Config

var config = await StatsigServer.GetConfig(user, "awesome_product_details");
var itemName = config.Get<string>("product_name", "Awesome Product v1");
var price = config.Get<double>("price", 10.0);

Getting a Layer/Experiment

// Values via GetLayer
var layer = await StatsigServer.GetLayer(user, "user_promo_experiments");
var title = layer.Get<string>("title", "Welcome to Statsig!");
var discount = layer.Get<double>("discount", 0.1);

// or, via GetExperiment
var experiment = await StatsigServer.GetExperiment(user, "new_user_promo");
var expTitle = experiment.Get<string>("title", "Welcome to Statsig!");
var expDiscount = experiment.Get<double>("discount", 0.1);

var price = msrp * (1 - discount);

Logging an Event

To track custom events and measure how features or experiment groups affect those events, call the Log Event API. Specify the user and event name to log, and optionally provide a value and metadata object:

StatsigServer.LogEvent(user, "add_to_cart", "SKU_12345", 
    new Dictionary<string, string> {
        { "price", "9.99" },
        { "item_name", "diet_coke_48_pack" }
    });

Statsig User

In addition to userID, email, ip, userAgent, country, locale, and appVersion are available as top-level fields on StatsigUser. You can also pass any key-value pairs in an object/dictionary to the custom field to create targeting based on them.

Typing on the StatsigUser object is lenient: you can pass numbers, strings, arrays, objects, and even enums or classes. However, evaluation operators only work on primitive types, mostly strings and numbers. The SDK attempts to cast custom field types to match the operator, but evaluation results for other types are not guaranteed. For example, an array set as a custom field is only compared as a string: there is no operator to match a value within that array.

Private Attributes

To keep sensitive user PII data out of logs, use the privateAttributes field on the StatsigUser object. This field accepts an object/dictionary of private user attributes. Any attribute set in privateAttributes is used only for evaluation/targeting and is removed from all logs before Statsig sends them to its servers.

For example, if a feature gate should only pass for users with emails ending in "@statsig.com", but you don't want to log email addresses to Statsig, add the key-value pair { email: "my_user@statsig.com" } to privateAttributes on the user.

Shutdown

To gracefully shutdown the SDK and ensure all events are flushed:

await StatsigServer.Shutdown();