如何将 DbContext 注入 NRules class 构造函数？

Question

我正在使用 NRules 定义规则并尝试在 NRules 基础 class 中使用接口，但出现问题，我收到 "No parameterless constructor defined for this object" 错误。这是我的接口定义

{
    public interface ICalcDiscount
    {
        public void ApplyPoint(int point);
    }
    public class CalcDiscount:ICalcDiscount
    {
        private readonly UniContext _context;

       public CalcPoint(UniContext context)
        {
            _context = context;

        }

        public  void ApplyDiscount(int d)
        {
           _context.Discount.Add(new Discount{ CustomerId = 1, d= d});
           _context.SaveChanges();
        }
    }
}

N规则Class

 public class PreferredCustomerDiscountRule : Rule
    {
        private readonly ICalcDiscount _d;

        public PreferredCustomerDiscountRule(ICalcDiscount d)
        {
            _d = d;
        }
        public override void Define()
        {
            Book book = null;


            When()

                .Match(() => book);


            Then()
                .Do(ctx => _c.ApplyDiscount(10));

        }

    }

我在 NRules 开始加载程序集时收到错误消息 MissingMethodException: 没有为此对象定义无参数构造函数。

 //Load rules
    var repository = new RuleRepository();
    repository.Load(x => x.From(typeof(PreferredCustomerDiscountRule).Assembly));//problem is here!
 //Compile rules
    var factory = repository.Compile();

Answer 1

如错误所述，您不能拥有包含参数的构造函数的规则。

您还应该解决规则定义内部的依赖关系，如 NRules wiki 上的 Rule Dependency 所示。

因此，您的 class 应该如下所示：

public class PreferredCustomerDiscountRule : Rule
    {
        public override void Define()
        {
            Book book = null;
            ICalcDiscount discountService = null;

            Dependency()
                .Resolve(() => discountService);

            When()
                .Match(() => book);


            Then()
                .Do(_ => discountService.ApplyDiscount(10));

        }

    }

如何将 DbContext 注入 NRules class 构造函数？

How to inject DbContext into NRules class constructor?

c#

nrules