c# - AutoMapper 将目标对象上的属性设置为 null

Question

我有这样的东西:

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());

要从我使用的 DomainEntity 获取 ApiEntity var apiEntity = Mapper.Map<DomainEntity, ApiEntity>(myDomainEntity);

要从我使用的 ApiEntity 中获取合并的 DomainEntity var domainEntity = Mapper.Map(myApiEntity, myDomainEntity);

但是当使用它时，属性 OtherEntities和 AnotherEntities设置为 null - 即使它们在从 myApiEntity 调用映射之前具有值至 myDomainEntity .我怎样才能避免这种情况，使它们真正合并而不仅仅是替换值？

感谢您的帮助。

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());