ASP.NET Core MVC Interview Question #129

What is the difference between constructor injection and action injection?

Dependency Injection, Services, Error Handling, Logging & Performance Senior Advanced

Quick Interview Answer

Constructor injection supplies dependencies when the controller is created and is appropriate for services used by several actions. Action injection supplies a service only to a particular action, commonly through FromServices or service-binding support.

Detailed Explanation

Constructor injection is usually clearer for core controller dependencies. Action injection can be useful for a dependency needed by only one action, but excessive use can make dependencies less visible at the controller level.

Code Example

public IActionResult Report(
    [FromServices] IReportGenerator generator)
{
    var report = generator.Generate();
    return View(report);
}