Dependency Injection in Episerver and .Net
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The document discusses dependency injection in Episerver and .NET, emphasizing its importance for testability and loose coupling. It covers various techniques such as constructor injection, property injection, and method injection, while also mentioning anti-patterns and best practices in implementing dependency injection. Additionally, it highlights the significance of frameworks and proper setup for achieving effective dependency management.
![@tech_fellow
Main(string[] args)
Global.asax & IControllerFactory
Startup.cs & RouterMiddleware
..rely on framework..](https://image.slidesharecdn.com/2017-10-episerverpartnerclose-up-dependencyinjection-171216191558/85/Dependency-Injection-in-Episerver-and-Net-24-320.jpg)
![[Fact]
public void TestMethod1()
{
var kpi = new Kpi();
kpi.Evaluate(this, new EventArgs());
...
}](https://image.slidesharecdn.com/2017-10-episerverpartnerclose-up-dependencyinjection-171216191558/85/Dependency-Injection-in-Episerver-and-Net-38-320.jpg)
![@tech_fellow
[ServiceConfiguration( … )]](https://image.slidesharecdn.com/2017-10-episerverpartnerclose-up-dependencyinjection-171216191558/85/Dependency-Injection-in-Episerver-and-Net-64-320.jpg)
Dependency Injection in Episerver and .Net
- 6. wałdis iljuczonok (aka technical fellow) tech guy at getadigital.com (Microsoft .Net + Episerver) ◦ MVP @tech_fellow
- 7. Why?
- 8. Testability
- 11. public class Class1 { public Class1() { } public Answer Method1(string directory) { // .... return ...; } }
- 12. @tech_fellow «DI is a set of principles and patterns that enable loose coupling* » * - http://blog.ploeh.dk/2010/04/07/DependencyInjectionisLooseCoupling/
- 15. Patterns
- 16. public class Class1 { private readonly ISomeService _service; public Class1(ISomeService service) { _service = service; } public IAnotherService AnotherService { private get; set; } public Answer Method1(IThirdService thridService) { return thridService.CouldBe() ? Answer.Yes() : Answer.No(); } } Constructor Injection Property Injection Method Injection
- 17. public static class AmbientContext { public static ISomeService TheService { get; } = new SomeService(); } Ambient Context
- 20. Layered
- 21. Onion
- 22. hexagonal
- 23. pizza
- 24. @tech_fellow Main(string[] args) Global.asax & IControllerFactory Startup.cs & RouterMiddleware ..rely on framework..
- 26. Anti-Patterns
- 28. public class Class1 { private readonly ISomeService _service; public Class1(ISomeService service) { _service = service; } public IAnotherService AnotherService { private get; set; } public Answer Method1(IThirdService thridService) { return thridService.CouldBe() ? Answer.Yes() : Answer.No(); } }
- 29. public class Class1 { private readonly ISomeService _service; public Class1() { _service = new SomeService(); } public IAnotherService AnotherService { private get; set; } public Answer Method1() { var thridService = new ThirdService(); return thridService.CouldBe() ? Answer.Yes() : Answer.No(); } }
- 31. public class Class1 { private readonly ISomeService _service; public Class1() { _service = new SomeService(); } public IAnotherService AnotherService { private get; set; } public Answer Method1() { var thridService = new ThirdService(); return thridService.CouldBe() ? Answer.Yes() : Answer.No(); } }
- 32. public class Class1 { private readonly ISomeService _service; public Class1(ISomeService service) { _service = service; } public Class1() { _service = new SomeService(); } public IAnotherService AnotherService { private get; set; } public Answer Method1() { var thridService = new ThirdService(); return thridService.CouldBe() ? Answer.Yes() : Answer.No(); } }
- 33. @tech_fellow Control Freak Bastard Injections Constrained Construction
- 35. @tech_fellow Control Freak Bastard Injections Constrained Construction Service Locator
- 38. [Fact] public void TestMethod1() { var kpi = new Kpi(); kpi.Evaluate(this, new EventArgs()); ... }
- 39. @tech_fellow
- 43. Don’t ask, we will call you! Hollywood Principle
- 44. DI in Episerver
- 51. @tech_fellow Episerver Developer Tools AddOn
- 53. @tech_fellow Libraries are designed to be «consumed»
- 59. public delegate object SingleInstanceFactory(Type target); public class TypeAbstractFactory { private readonly SingleInstanceFactory _factory; public TypeAbstractFactory(SingleInstanceFactory factory) { _factory = factory; } private void CreateTargetType() { var s = (ISomeService)_factory(typeof(ISomeService)); } }
- 60. context.Container.Configure( c => c.For<SingleInstanceFactory>() .Use<SingleInstanceFactory>(ctx => ctx.GetInstance));
- 61. public delegate object SingleInstanceFactory(Type target); public class TypeAbstractFactory { private readonly SingleInstanceFactory _factory; public TypeAbstractFactory(SingleInstanceFactory factory) { _factory = factory; } private void CreateTargetType() { var s = (ISomeService)_factory(typeof(ISomeService)); } }
- 67. public delegate object SingleInstanceFactory(Type target); public class TypeAbstractFactory { private readonly SingleInstanceFactory _factory; public TypeAbstractFactory(SingleInstanceFactory factory) { _factory = factory; } private void CreateTargetType() { var s = (ISomeService)_factory(typeof(ISomeService)); } }
- 69. Extra Bonus with DI
- 72. @tech_fellow Validation Pre/post processing Authorization Logging Auditing Event dispatching Notifications Unit of work/transactions ...
- 73. @tech_fellow Create loose-coupling code Demand dependencies from consumer Leverage DI container features Look for anti-patterns
- 74. @tech_fellow Be a BOY SCOUT!
Editor's Notes
- #14: DI fuels SOLID
- #15: DI fuels SOLID Dependency Inversion Principle (the D in SOLID) is the guiding principle behind DI.
- #20: Compose whole graph and get DI container out of way in layers below. Read bottom-up = to understand dependency graph and required dependencies for other services.
- #28: Cannot replace dependencies after application has been compiled (in unit tests). Drags unnecessary dependencies.
- #31: Main problem – it uses FOREIGN DEFAULT
- #34: We lose flexibility. Fx does not know what exactly component will need for composition.
- #36: The essence here – is not how component is constructed, but how it’s used.
- #49: EPiServer.Forms.Core.PostSubmissionActor.ActorsExecutingService
- #64: Refactor to Facasde Services, makes it easy to see and react on violation of SRP.
- #65: Frameworks are designed with Dependency Inversion in mind. You implement interface, register it (in composition root) and framework calls you. Framework is the consumer of the client code. It CREATES instances of the client code!
- #66: It hides registration details that would be explicitly visible in composition root (no room for 2 in container) How to unregister (clear out) previous registrations for an object? It’s hard to know lifetime of the dependency (wrong assumptions could be made)
- #72: Respects Open/Closed Principle, Liskov comes into play