asked on

C# - Interface instantiating question

Hello all,

I have a question in regard to calling a method signature in my interface. We have a BaseController class where in that we have interfaces defined such as:

protected ICustomerService CustomerService;
protected IGroupService GroupService;

Then in controllers in an MVC project we instantiate in the constructor for example:

public class HomeController : BaseController
{
public HomeController(ICustomerService customerService, IGroupService grpService)
{
CustomerService = customerService;
GroupService = grpService;
}

//then in my action I can do for example
var qry = CustomerService.GetAllCustomers(0);
}

May not be 100% on syntax but that should make sense. Now I have a class I am using to implement a custom role provider for the project. Such as this:

public class MyRoleProvider : RoleProvider
{
}

How do I instantiate the same interfaces as done in the controller example? I can't inherit the BaseController in this case it is outside my controller and it would not make sense. This is just a class nothing to do with controllers. Hope this makes some sense. :). Just need to see how can I call the GetAllCustomers in my CustomerService interface in the MyRoleProvider class here?

ASKER CERTIFIED SOLUTION

Armand G

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Dmitry G

In some sense there are no difference between just a class and controller - both are classes.

In your controller class there is no instantiation for ICustomerService interface. You just pass an instance of ICustomerService into a constructor. ICustomerService and IGroupService objets are instantiated somewhere else (obviously, there are classes that implemeny these interfaces).

Similarly, in your RoleProvider or MyRoleProvider you may add a constructor that takes ICustomerService as an argument.

Dmitry G

2 armchang

Not quite correct code. The line

var qry = CustomerService.GetAllCustomers(0);

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should be inside of some method,otherwise you'll have an error.

Armand G

@anarki_jimbel

Yes, I know. That is why he had a comment on it, that it should be put inside a method that returns an ActionResult but thanks anyway.

sbornstein2

ASKER

I will try these tomorrow. I was getting an object not set to an instance of an object type error I think though Armchang on the GetCustomer call trying like what you have but I will check again tomorrow. I had to add a blank parameter constructor then below it like what you have but the call was not getting into it with an Object ref error. I will check again.

sbornstein2

ASKER

Yes these don't work. The role provider is defined in the web config and it says 'no parameter less constructor' So I add that such as this:

public class MyRoleProvider : RoleProvider
{
protected ICustomerService CustomerService;
protected IGroupService GroupService;

public MyRoleProvider()
{
}

public MyRoleProvider(ICustomerService customerService, IGroupService grpService)
{
CustomerService = customerService;
GroupService = grpService;
}

private User GetCurrentUser()
{
var qry = CustomerService.GetAllCustomers(0); //error happens - Object reference not set to an instance of an object.
}
}

sbornstein2

ASKER

thanks