NOTE: If you are looking for how to generate an instance of ServiceProvider, outside of NET Core runtime, like for a unit test, see this: [Duplicating .NET Core DI](https://wiki.galaxydump.com/link/229 "https://wiki.galaxydump.com/link/229")
Here’s a good reference on how DI scoping works: [The dangers and gotchas of using scoped services in IConfigureOptions](https://andrewlock.net/the-dangers-and-gotchas-of-using-scoped-services-when-configuring-options-in-asp-net-core/) See this for resolving services during startup: [Consuming Services Inside Startup](https://wiki.galaxydump.com/link/225 "https://wiki.galaxydump.com/link/225") Any service added in ConfigureServices via startup.cs or program.cs, can be access multiple ways. ## Controller Constructor Injected into the constructor of a controller, and used by an action: ```c# public class HomeController : Controller { private INotificationHelper helper = null; public HomeController(INotificationHelper helper) { this.helper = helper; } public IActionResult Index() { helper.Notify(); return View(); } } ``` ## Controller Action Injected into an action (if only a few actions of a controller need the service): ```c# public IActionResult Index([FromServices]INotificationHelper helper) { helper.Notify(); return View(); } ``` ## Unknown Service Needs If many services are needed by a controller, or it is unknown which services will be required, the service provider can be injected instead: ```c# public class HomeController : Controller { private IServiceProvider provider = null; public HomeController(IServiceProvider provider) { this.provider = provider; } public IActionResult Index() { INotificationHelper helper = (INotificationHelper) provider.GetService(typeof(INotificationHelper)); helper.Notify(); return View(); } } ``` ## From an Http Context Any service can be used where an HTTP context is available: NOTE: Be sure to test that the returned service instance is NOT null before use. ```c# public IActionResult Index() { INotificationHelper helper = (INotificationHelper) HttpContext.RequestServices.GetService(typeof(INotificationHelper)); return View(); } ``` ### Services from New Scope Here’s a method of how to create a service or data context from a new scope. This can be useful if spawning an asynchronous database operation from a web controller, that must run independently (fire-and-forget). Such a scenario would normally trigger a disposed exception because the data context would get disposed with the rest of the resources in the web call (because they went out of scope). This method creates a new scope, from a service provider. ```c# static private void Accept_UserDevice_TokenData(IServiceScopeFactory svcscopefactory, DeviceToken_DTO tokendata, string corelationid) { // Run all this inside its own thread... _ = Task.Run(() => { ClientToken_v1 ct = null; IServiceScope newscope = null; try { // Create the service scope in a try-finally, so it will get automatically disposed... newscope = svcscopefactory.CreateScope(); Bliss.Notifications.DataContexts.DataContext dbctx = null; try { // Create the data context inside a try-finally, so it can be automatically disposed... dbctx = newscope.ServiceProvider.GetRequiredService