What is transient in the context of C#?

In the context of C#, the keyword transient is not part of the language syntax. It likely refers to the concept of Transient Lifetime in dependency injection (DI) containers).

With Transient Lifetime, each time a service instance is requested, the DI container creates a new instance of that class.

Features of Transient Lifetime:

• New instance on each request: Isolates service usage, preventing unwanted side effects between different consumers.
• High overhead: Creation and destruction of objects happen more frequently.
• Suitable for lightweight, stateless services: Where there is no need to maintain state between calls.

Example of registering a Transient service in .NET Core/5+:

// In the ConfigureServices method of the Startup class
public void ConfigureServices(IServiceCollection services)
{
    services.AddTransient<IMyService, MyService>();
}

Comparison of Lifetime Scopes (Transient, Scoped, Singleton):

Lifetime Scope	Description	When used
Transient	A new instance is created on each service request.	For lightweight, stateless services.
Scoped	A new instance is created once per scope lifetime (e.g., per HTTP request).	For services tied to a specific context (e.g., database context).
Singleton	The same instance is used throughout the application's lifetime after the first request.	For services requiring state sharing or expensive initialization.