AutoMapper忽略映射有条件地，当ViewModel中的List属性为null时

Question

我的视图模型如下：

File file = new File(Environment.getExternalStorageDirectory() + "/ExpensesApp/expensesData.xls");

实体：

public class CarViewModel
{
    public Guid Id { get; set; }
    public string CarName { get; set; }
    public List<EngineTypeViewModel> Engine { get; set; }
}

public class EngineTypeViewModel
{
    public int Id { get; set; }
    public string name { get; set; }
}

我想将CarViewModel映射到Car Entity类型，如下所示：

public class Car
{
    public Guid Id { get; set; }
    public string CarName { get; set; }
    public virtual ICollection<EngineType> Engine { get; set; }
}
public class EngineType
{
    public int Id { get; set; }
    public string name { get; set; }
}

在映射配置中，我想从CreateMap<CarViewModel, Car>() .ForMember(dest => dest.Engine, src => src.Ignore()); 映射到CarViewModel。 但是如果引擎Car那么映射应该被忽略。

count is 0

这意味着在我使用CreateMap<CarViewModel, Car>() .ForMember(dest => dest.Engine, src => src.Ignore()); //Map only when src.Engine.Count > 0 other wise Ignore // What should be my approach here?? 进行更新时。像

GetById

Auto mapper中是否有此任务的扩展名。我已按上述public Update(CarViewModel model) { var car = obj.GetById(model.Id); var mapped = map.Map(model,car); //if the model.Engine.Count = 0 car.Engine //should be same as mapped.Engine, there should not be mapping with the //object(Engine) from the `CarViewModel` } 进行了尝试，它也将在src.Ignore()期间忽略。

因此，我不想在更新期间映射空值。或者，它应保留为目标值

编辑：

AutoMapper配置：

ADD

映射记录：

CreateMap<CarViewModel, Car>().ForMember(dest => dest.Engine, o =>
{
    o.Condition(src => src.Engine.Count > 0);

    //mapping
    o.MapFrom(src => src.Engine);
});

您可以查看var carmodel = new CarViewModel(); carmodel.CarName = "Maruti"; carmodel.Id = Guid.NewGuid(); var carentity = new Car(); carentity.CarName = "Maruti"; carentity.Id = Guid.NewGuid(); carentity.Engine.Add(new EngineType { Id = 1, name = "PetrolEngine" }); carentity.Engine.Add(new EngineType { Id = 2, name = "DieselEngine" }); carentity.Engine.Add(new EngineType { Id = 3, name = "CranotEngine" }); var mapped = _mapper.Map(carmodel, carentity); 。 mapped

预期产出：