CODEWITHSUNDEEP
c#dependency-injectioninversion-of-control
RealityDysfunction
RealityDysfunction

Reputation: 2639

Dependency injection, but not into a controller

I recently began experimenting with DI. I am using Unity Ioc to inject an EmailService from by Business Logic Layer into EmailServiceWrapper in the presentation layer which is then instantiated, my code is as follows: 

public class EmailServiceWrapper : IIdentityMessageService
{
    private readonly IEmailService _emailService;
    public EmailServiceWrapper(IEmailService emailService)
    {
        this._emailService = emailService;
    }
    public async Task SendAsync(IdentityMessage message)
    {
        await _emailService.configSendGridasync(message.Body, message.Subject, new MailAddress(message.Destination));
    }
}

I register the mapping like so: 

    public static void RegisterTypes(IUnityContainer container)
    {
        container.RegisterType<IEmailService, EmailServiceGmail>();
    }

Finally in my ApplicationUserManager.cs I try to do the following: 

    appUserManager.EmailService = new EmailServiceWrapper(); //Dependency injection?

I get an error: "EmailServiceWrapper" does not have a constructor that takes 0 arguments. I am aware of what this means, but I am not sure how to set this up, I've seen many examples online about injecting dependencies into controllers but what about this case? Any help?

Upvotes: 1

Views: 44

Answers (1)

Julia Hayward
Julia Hayward

Reputation: 2155

The aim of Unity is that you don't explicitly construct objects yourself, with all the inner constructors that would require; instead you get the container to do it for you:

appUserManager.EmailService = container.Resolve<EmailServiceWrapper>();

The point of 

container.RegisterType<IEmailService, EmailServiceGmail>();

is to give the container the information it needs to new up any object that requires an IEmailService.

Upvotes: 3

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