How to reduce number of parameter in constructor, half of them is to feed for base class

Question

I got this code smells from Sonarqube: "Constructor has 8 parameters, which is greater than the 7 authorized"

The class is not big, just under 100 lines of codes, but 4 parameters need to pass to the base class. These parameters were injected from DI, so I can not create another model and put them all into it.

I just have one solution is to use IServiceProvider in the base class, so I can reduce a lot of parameters. But in my opinion, use ServiceProvider make the code less clean

public class BaseClass : AuthenticationHandler (Microsoft class)
{
   private readonly IE e;
   private readonly IF f;
   private readonly IG g;

   protected BaseClass(IA a, IB b, IC c, ID d, IE e, IF f, IG g) 
       : base(a, b, c, d)
   {
      this.e = e;
      this.f = f;
      this.g = g;
   }

   //some method use e,f,g
}

public class ChildClass : BaseClass
{
   private readonly IH h;

   // code smell here
   public ChildClass(IA a, IB b, IC c, ID d, IE e, IF f, IG g) 
        : base(a, b, c, d, e, f, g)
   {
      this.h = h;
   }

   //some method use h
}

Is there any solution can help me reduce the parameter in this case but still keep the code clean and readable?

Thanks for attention.

This is an AuthenticationHandler class, it use in Startup.cs. Something like: ```.AddScheme``` — Thiện Sinh, Nov 06 '19 at 08:00
you could use reflection to set the value of h after the initialization of the Child Class — Frenchy, Nov 06 '19 at 09:23
How reflection can get an instance from the DI container, use reflection is not a good idea anyway, I would rather user IServiceProvider instead, I need some clean pattern — Thiện Sinh, Nov 06 '19 at 09:34

How to reduce number of parameter in constructor, half of them is to feed for base class

0 Answers0