Need to create parameterized constructor in webAPI

Question

I need some sample example with parameterized constructor using reprository and web-API

I tried this:

public class TestUserController : ApiController
{

private readonly IUserRepository UserRepository;

public TestUsersController()
{

}
public TestUsersController(IUserRepository UserRepository)
{
this.UserRepository = UserRepository;.........this parameterized constructor is not hitting and getting always null
}

Anjali Kumari · Answer

I was trying to do what have you shared but didn't get I was asking to give the sample example that in my above code involving the dependency injection what I need to do work?

Saravanan V · Answer

Thought you had already know some basics about DI by seeing your code. Dependency Injection (DI) is a design pattern that demonstrates how to create loosely coupled classes. It is a technique for achieving loose coupling between objects and their collaborators or dependencies. You should be able to get hold of DI after reading this article. http://www.c-sharpcorner.com/UploadFile/ff2f08/dependency-injection-pattern/ In your code you are trying to inject an object of a class that implements the IUserRepository interface. The advantage of using DI is if you want to change the implementation logic for user repository you could just create another class which has the new implementation. In this regard you don't have change all of your controllers class code ( which has IUserRepository as parameter in constructor) since the dependency or the new implementation will be dynamically injected by the DI framework. Lot of DI frameworks are available in the market. Unity (from Microsoft) Autofac StructureMap Ninject are few of the popular frameworks in the market. You need to figure out which one best suits for your project. Once you pick a DI framework you can install it to your solution using the Nuget package manager in Visual Studio. Then you need to register all the types (classes) that implements the interfaces. Once this configuration is done and you run the application the DI framework would inject the dependencies for all of the required controllers. You can use the DI framework for the regular MVC controllers and Web API controllers. Other Useful Links for references: https://msdn.microsoft.com/en-us/library/hh323705(v=vs.100).aspx https://docs.microsoft.com/en-us/aspnet/core/fundamentals/dependency-injection http://www.c-sharpcorner.com/UploadFile/33b051/dependency-injection-using-microsoft-unity/ http://www.c-sharpcorner.com/UploadFile/eec362/dependency-injection-in-mvc/ When You Shouldn’t Use Dependency Injection https://msdn.microsoft.com/en-us/library/dn178469(v=pandp.30).aspx Please mark this answer as accepted if it fullfills your question.

Anjali Kumari · Answer

I already search the links what you shared but I didn't get what is dependency Injection please explain clearly How to use it also.I tried in google am not able to do

Saravanan V · Answer

It looks like you are trying to inject the dependency for Web API controller. You need to remove the parameterless constructor and keep the parameterized constructor. Then you have to make sure the dependency injection is rightly configured for all of your repositories before actually using them in the controllers. Having all of these in place the dependency for the constructor will be properly injected by the framework when an object for the controller is created. Please find below links for your reference on implementing Dependency Injection in Web API. https://docs.microsoft.com/en-us/aspnet/web-api/overview/advanced/dependency-injection http://www.c-sharpcorner.com/UploadFile/1492b1/restful-day-2-inversion-of-control-using-dependency-injecti/ https://stackoverflow.com/questions/33614296/mvc-web-api-and-unity-for-dependency-injection https://www.devtrends.co.uk/blog/using-unity.mvc5-and-unity.webapi-together-in-a-project Hope this helps you.