使用Automapper更新集合是指在自定义映射时，需要同时更新现有集合中的项。为实现这一目的，可使用Automapper的自定义映射功能，并使用AddCollectionMapping()方法。下面是一个示例代码：

//定义对象模型 public class Source { public ICollection Destinations { get; set; } }

public class Destination { public string Name { get; set; } }

//定义自定义映射 var config = new MapperConfiguration(cfg => { cfg.CreateMap() .ForMember(dest => dest.Destinations, opt => opt.MapFrom(src => src.Destinations)) .ForAllMembers(opts => opts.Condition((src, dest, srcMember) => srcMember != null)); });

var mapper = config.CreateMapper();

//测试代码 var source = new Source { Destinations = new List { new Destination { Name = "Destination 1" }, new Destination { Name = "Destination 2" } } };

var destination = new Source { Destinations = new List { new Destination { Name = "Destination 3" }, new Destination { Name = "Destination 4" } } };

//调用Mapper mapper.Map(source, destination);

//输出测试结果 foreach (var item in destination.Destinations) { Console.WriteLine(item.Name); }

输出结果为： Destination 1 Destination 2

可以看到，使用自定义映射更新集合时，现有集合的项并未被覆盖。