如何在FluentValidation中实现OR条件的属性验证？

需求明确：

• 当EquipmentId > 0时，ActualEquipmentTypeId必须匹配FirstRequestedEquipmentTypeId 或 SecondRequestedEquipmentTypeId
• 若两个请求类型都与实际类型不匹配，返回验证错误

尝试过两种写法都无效：
第一种写法中.Or不是FluentValidation的有效语法：

public class BookingEquipmentModelValidator : AbstractValidator<BookingEquipmentModel>
{
    public BookingEquipmentModelValidator()
    {
        RuleFor(be => be.BookingId).GreaterThan(0);
        RuleFor(be => be.BookingSlotId).GreaterThan(0);
        RuleFor(be => be.GeneralVentSetting).MaximumLength(50);
        RuleFor(be => be.Comments).MaximumLength(254);
        RuleFor(be => be.SealNumber).MaximumLength(15);
        
        When(be => be.EquipmentId > 0, () =>
        {
            RuleFor(be => be.ActualEquipmentTypeId).Equals(be => be.FirstRequestedEquipmentTypeId).Or
                .Equals(be => be.SecondRequestedEquipmentTypeId).WithMessage("No Match on either Req1 or Req2");
        });
    }
}

第二种写法逻辑错误，无法正确触发验证：

When(be => be.EquipmentId is > 0, () =>
{
    RuleFor(be => be.ActualEquipmentTypeId != be.SecondRequestedEquipmentTypeId && be.ActualEquipmentTypeId != be.FirstRequestedEquipmentTypeId).Equals(true);
});

希望找到无需冗余代码的简洁实现方式。

简洁解决方案 #

使用Must方法结合Lambda表达式直接实现OR逻辑，这是最直接的方式：

public class BookingEquipmentModelValidator : AbstractValidator<BookingEquipmentModel>
{
    public BookingEquipmentModelValidator()
    {
        RuleFor(be => be.BookingId).GreaterThan(0);
        RuleFor(be => be.BookingSlotId).GreaterThan(0);
        RuleFor(be => be.GeneralVentSetting).MaximumLength(50);
        RuleFor(be => be.Comments).MaximumLength(254);
        RuleFor(be => be.SealNumber).MaximumLength(15);
        
        When(be => be.EquipmentId > 0, () =>
        {
            RuleFor(be => be.ActualEquipmentTypeId)
                .Must((model, actualTypeId) => 
                    actualTypeId == model.FirstRequestedEquipmentTypeId || 
                    actualTypeId == model.SecondRequestedEquipmentTypeId)
                .WithMessage("No Match on either Req1 or Req2");
        });
    }
}

说明 #

Must方法支持同时接收当前属性值和整个模型实例，让你可以轻松对比多个属性间的关系，完美实现OR逻辑，代码简洁且易读。

内容的提问来源于stack exchange，提问作者Rob Ainscough