Factory_Service_3.cs

using Microsoft.AspNetCore.Mvc;
using System;

namespace JrTech.AspNetCore.Web.Controllers
{
    [Route("api/[controller]")]
    public class ValuesController : Controller
    {
        private readonly Func<IRandomNumberGenerator> _numberGeneratorFactory;

        public ValuesController(Func<IRandomNumberGenerator> numberGeneratorFactory)
        {
            _numberGeneratorFactory = numberGeneratorFactory;
        }

        // GET api/values
        [HttpGet]
        public string Get()
        {
            var generator = _numberGeneratorFactory();

            return $"randomNumber - {generator.Get()}" ;
        }
    }
}