In C#, when registering services in the dependency injection container (usually in the
ConfigureServices method of the
Startup class), you have three options:
AddSingleton. These methods determine the lifetime of the registered services, meaning how long instances of the service will be kept in memory and how they will be shared among different parts of your application.
AddTransientmethod registers a new instance of the service every time it is requested by any part of the application.
// Assume we have a service called MyTransientService implementing IMyService interface. // When a service is registered as transient, a new instance is returned every time it is resolved. services.AddTransient<IMyService, MyTransientService>();
See Using a Transient Scope with repositories or data access services for a more robust example of when to use a transient scope.
AddScopedmethod registers a single instance of the service per scope. A scope could be an HTTP request or any other defined scope, depending on the application setup (e.g., web applications with web requests, or using an explicit scope in other scenarios).
// Assume we have a service called MyScopedService implementing IMyService interface. // When a service is registered as scoped, the same instance is returned within the same scope. services.AddScoped<IMyService, MyScopedService>();
See Using a Scoped service to deal with stateful operations or maintaining data across multiple method calls for a more robust example of when to use a scoped service.
AddSingletonmethod registers a single instance of the service for the entire lifetime of the application.
// Assume we have a service called MySingletonService implementing IMyService interface. // When a service is registered as singleton, the same instance is returned for the entire application lifetime. services.AddSingleton<IMyService, MySingletonService>();
See Use a singleton service to manage a shared resource or state that needs to be accessed by multiple parts of the application throughout its lifetime for a more robust example of using a singleton service in C#.
Choosing the appropriate lifetime for your services is essential for managing resource usage and ensuring the correctness of your application. Always consider the statefulness and the desired behavior of your services when selecting between