我有一个应用程序，我试图使用至少一个名义上的 DDD 类型的域模型来构建，并且正在努力解决某个部分。
我的实体有一些业务逻辑，这些逻辑使用我当前在某些域服务中拥有的一些财务计算和费率计算，以及我放入值对象中的一些常量值。
我正在努力解决如何让实体使用域服务内部的逻辑，或者这些服务内部的逻辑是否属于那里。这是我到目前为止所拥有的：
public class Ticket
{
public Ticket(int id, ConstantRates constantRates, FinancialCalculationService f, RateCalculationService r)
{
Id = id;
ConstantRates = constantRates;
FinancialCalculator = f;
RateCalculator = r;
}
private FinancialCalculationService FinancialCalculator { get; set; }
private RateCalculationService RateCalculator { get; set; }
private ConstantRates ConstantRates { get; set; }
public int Id { get; private set; }
public double ProjectedCosts { get; set; }
public double ProjectedBenefits { get; set; }
public double CalculateFinancialGain()
{
var discountRate = RateCalculator.CalculateDiscountRate(ConstantRates.Rate1, ConstantRates.Rate2,
ConstantRates.Rate3);
return FinancialCalculator.CalculateNetPresentValue(discountRate,
new[] {ProjectedCosts*-1, ProjectedBenefits});
}
}
public class ConstantRates
{
public double Rate1 { get; set; }
public double Rate2 { get; set; }
public double Rate3 { get; set; }
}
public class RateCalculationService
{
public double CalculateDiscountRate(double rate1, double rate2, double rate3 )
{
//do some jibba jabba
return 8.0;
}
}
public class FinancialCalculationService
{
public double CalculateNetPresentValue(double rate, params double[] values)
{
return Microsoft.VisualBasic.Financial.NPV(rate, ref values);
}
}
我觉得其中一些计算逻辑确实属于这些域服务，但我真的不喜欢这样，我必须从我的存储库手动注入这些依赖项。是否有其他建模方法？我不喜欢这样有错吗？
读过蓝皮书但之前没有真正以这种风格构建过任何东西，我正在寻找指导。
EDIT
感谢大家的反馈！根据我所听到的，听起来我的模型应该如下所示。这个看起来更好一些？
public class Ticket
{
public Ticket(int id)
{
Id = id;
}
private ConstantRates ConstantRates { get; set; }
public int Id { get; private set; }
public double ProjectedCosts { get; set; }
public double ProjectedBenefits { get; set; }
public double FinancialGain { get; set; }
}
public class ConstantRates
{
public double Rate1 { get; set; }
public double Rate2 { get; set; }
public double Rate3 { get; set; }
}
public class FinancialGainCalculationService
{
public FinancialGainCalculationService(RateCalculationService rateCalculator,
FinancialCalculationService financialCalculator,
ConstantRateFactory rateFactory)
{
RateCalculator = rateCalculator;
FinancialCalculator = financialCalculator;
RateFactory = rateFactory;
}
private RateCalculationService RateCalculator { get; set; }
private FinancialCalculationService FinancialCalculator { get; set; }
private ConstantRateFactory RateFactory { get; set; }
public void CalculateFinancialGainFor(Ticket ticket)
{
var constantRates = RateFactory.Create();
var discountRate = RateCalculator.CalculateDiscountRate(constantRates.Rate1, constantRates.Rate2,
constantRates.Rate3);
ticket.FinancialGain = FinancialCalculator.CalculateNetPresentValue(discountRate,
new[] {ticket.ProjectedCosts*-1, ticket.ProjectedBenefits});
}
}
public class ConstantRateFactory
{
public ConstantRates Create()
{
return new ConstantRates();
}
}
public class RateCalculationService
{
public double CalculateDiscountRate(double rate1, double rate2, double rate3 )
{
//do some jibba jabba
return 8.0;
}
}
public class FinancialCalculationService
{
public double CalculateNetPresentValue(double rate, params double[] values)
{
return Microsoft.VisualBasic.Financial.NPV(rate, ref values);
}
}
领域模型在这一点上最终变得相当贫乏，但当我添加功能时，它可能会有更多功能。
EDIT 2
好吧，我得到了更多反馈，也许我的“计算”服务更像是我的实体可以依赖的策略对象。这是另一种方式，将更多逻辑返回到实体中，并利用这些策略对象。对此有何想法？直接在实体中实例化这些助手有什么问题吗？我认为我不想在测试中模拟这些对象，但是我也无法在不测试这些策略对象的情况下测试CalculateFinancialGain 方法。
public class Ticket
{
public Ticket(int id, ConstantRates constantRates)
{
Id = id;
ConstantRates = constantRates;
}
private ConstantRates ConstantRates { get; set; }
public int Id { get; private set; }
public double ProjectedCosts { get; set; }
public double ProjectedBenefits { get; set; }
public double CalculateFinancialGain()
{
var rateCalculator = new RateCalculator();
var financeCalculator = new FinanceCalculator();
var discountRate = rateCalculator.CalculateDiscountRate(ConstantRates.Rate1, ConstantRates.Rate2,
ConstantRates.Rate3);
return financeCalculator.CalculateNetPresentValue(discountRate,
ProjectedCosts*-1,
ProjectedBenefits);
}
}
public class ConstantRates
{
public double Rate1 { get; set; }
public double Rate2 { get; set; }
public double Rate3 { get; set; }
}
public class RateCalculator
{
public double CalculateDiscountRate(double rate1, double rate2, double rate3 )
{
//do some jibba jabba
return 8.0;
}
}
public class FinanceCalculator
{
public double CalculateNetPresentValue(double rate, params double[] values)
{
return Microsoft.VisualBasic.Financial.NPV(rate, ref values);
}
}
