Setup filter attribute for dependency injection to accept params in constructor

Question

I'm following a ninject filter attribute setup on this page.

For them, they have:

.WithConstructorArgumentFromControllerAttribute<LogAttribute>(
      "logLevel", attribute => attribute.LogLevel);

The second parameter is expecting a Func<LogAttribute, object> callback. Their actual param list is setup as follows:

Log(LogLevel = Level.Debug)

But my filter attribute is setup as follows:

public class AuthAttribute : FilterAttribute { }

public class AuthFilter : IAuthorizationFilter
{

    private readonly IUserService userService;
    private string[] roles;

    //Stuck on the constructor also. How do I accept params?
    public AuthFilter(IUserService userService, params string[] roles)
    {
        this.userService = userService;
        this.roles = roles;
    }
    public void OnAuthorization(AuthorizationContext filterContext)
    {
        throw new NotImplementedException();
    }
}

Somehow this is wrong. Because I want my filter to look like:

[Auth("Admin", "Contrib")]

My bindings:

 kernel.BindFilter<AuthFilter>(FilterScope.Controller, 0)
            .WhenControllerHas<AuthAttribute>()
            .WithConstructorArgumentFromControllerAttribute<AuthAttribute>("roles", /*Stuck here*/)

Answer 1

You need to make roles into a property in your attribute.

Attribute:

public class AuthAttribute : FilterAttribute 
{ 
  public string[] Roles { get; set; }

  public AuthAttribute(params string[] roles)
  {
      this.Roles = roles;
  }
}

Filter:

public class AuthFilter : IAuthorizationFilter
{

  private readonly IUserService userService;
  private readonly string[] roles;

  public AuthFilter(IUserService userService, string[] roles)
  {
    this.userService = userService;
    this.roles = roles;
  }

  public void OnAuthorization(AuthorizationContext filterContext)
  {
    //do stuff
  }
}

Controller

   [AuthAttribute("a", "b")]
   public class YourController : Controller 
   {

   }

Binding:

kernel.BindFilter<AuthFilter>(FilterScope.Controller, 0)
            .WhenControllerHas<AuthAttribute>()
            .WithConstructorArgumentFromControllerAttribute<AuthAttribute>("roles", attribute => attribute.Roles);