基于源和目标的 AutoMapper 条件映射

Question

我需要将UpdateViewModel映射到它的Model 。 Model是

public class Model
{
    // ...
    public DateTime? Disabled
}

UpdateViewModel是

public class UpdateViewModel
{
    // ...
    Status Status
}
public enum Status
{
    Disabled,
    Active
}

我现在有这个代码

if(uvm.Status == Status.Active)
{
    model.Disabled = null;
}
else
{
    if(model.Disabled == null)
    {
        model.Disabled = DateTime.UtcNow;
    }
}

我想在我的地图中得到这个，但我很难有一个 if/else 条件，我很难将Disabled设置为null 。

它应涵盖以下情况：

Model.Disabled == null 和 uvm.Status == Status.Disabled -> 将 model.Disabled 设置为 DateTime.UtcNow

Model.Disabled == null 和 uvm.Status == Status.Active -> 保持 model.Disabled = null

Model.Disabled != null 和 uvm.Status == Status.Disabled -> 保持当前 model.Disabled

Model.Disabled != null 和 uvm.Status == Status.Active -> 将 model.Disabled 设置为 null

Answer 1

我设法使用 IValueResolver 解决了这个问题

public class DisabledResolver : IValueResolver<UpdateViewModel, Model, DateTime?>
{
    public DateTime? Resolve(UpdateViewModel uvm, Model entity, DateTime? value, ResolutionContext context)
    {
        if(uvm.Status == Status.Active)
        {
            return null;
        }
        else
        {
            if(entity.Disabled == null)
            {
                return DateTime.UtcNow;
            }
            return entity.Disabled;
        }
    }
}

和

CreateMap<UpdateViewModel, Model>()
    .ForMember(model => model.Disabled, opt => opt.MapFrom<DisabledResolver>());

Answer 2

您可以为类型之间的映射创建自定义配置规则。 例如，

 var configuration = new MapperConfiguration(cfg => {
                cfg.CreateMap<UpdateViewModel, Model>()
                  .ForMember(dest => dest.Disabled, opt => opt.MapFrom((src,dest)=>
                  {
                      return src.Status switch
                      {
                          Status.Active => null,
                          Status.Disabled when dest.Disabled is null => DateTime.UtcNow,
                          Status.Disabled => dest.Disabled,
                          _ => throw new ArgumentException()
                      };

                  }));
            });

接着

var mapper = new Mapper(configuration);
var result = mapper.Map<UpdateViewModel,Model>(uModel,model);