c# - AutoMapper 将目标对象上的属性设置为 null

Question

我有这样的事情：

public class DomainEntity
{
    public string Name { get; set; }
    public string Street { get; set; }
    public IEnumerable<DomainOtherEntity> OtherEntities { get; set; }
    public IEnumerable<DomainAnotherEntity> AnotherEntities { get; set; }
}

public class ApiEntity
{
    public string Name { get; set; }
    public string Street { get; set; }
    public int OtherEntitiesCount { get; set; }
}

以及以下映射器配置：

Mapper.Configuration.AllowNullCollections = true;

Mapper.CreateMap<DomainEntity, ApiEntity>().
    ForSourceMember(e => e.OtherEntities, opt => opt.Ignore()).
    ForSourceMember(e => e.AntherEntities, opt => opt.Ignore()).
    ForMember(e => e.OtherEntitiesCount, opt => opt.MapFrom(src => src.OtherEntities.Count()));

Mapper.CreateMap<ApiEntity, DomainEntity>().
    ForSourceMember(e => e.OtherEntitiesCount, opt => opt.Ignore()).
    ForMember(e => e.OtherEntities, opt => opt.Ignore()).
    ForMember(e => e.AnotherEntities, opt => opt.Ignore());

从我正在使用的 DomainEntity 获取 ApiEntityvar apiEntity = Mapper.Map<DomainEntity, ApiEntity>(myDomainEntity);

从我正在使用的 ApiEntity 获取合并的 DomainEntityvar domainEntity = Mapper.Map(myApiEntity, myDomainEntity);

但是当使用它时，属性OtherEntities和AnotherEntities被设置为null- 即使它们在调用映射 from myApiEntityto之前有值myDomainEntity。我怎样才能避免这种情况，以便它们真正合并而不仅仅是替换值？

谢谢你的帮助。

Answer 1

我认为您正在寻找UseDestinationValue而不是Ignore：

Mapper.CreateMap<ApiEntity, DomainEntity>().
    ForSourceMember(e => e.OtherEntitiesCount, opt => opt.UseDestinationValue()).
    ForMember(e => e.OtherEntities, opt => opt.UseDestinationValue()).
    ForMember(e => e.AnotherEntities, opt => opt.UseDestinationValue());