ASP.NET Automapper 添加到地图配置文件中的对象列表

Question

创建 PersonalChatDto

1. 我首先创建 dto 并将 Chat 类映射到其中
2. 将成员选项映射到现有 dto
3. 将合作伙伴（我与之交谈的用户）映射到现有的 dto
4. 如果合作伙伴在通讯录中，我希望映射器获取

   List<AvatarDto> Avatars

   的值并将联系人中的头像添加到其中。

var partner = chat.Members.Single(u => u.Id != user.Id);

        var contact = await contactRepository.GetContactAsync(user.Id, partner.Id);

        var member = await personalChatMemberRepository.GetMemberAsync(chat.Id, user.Id);

        var dto = mapper.Map<PersonalChatDto>(chat);
        mapper.Map(member, dto);
        mapper.Map(partner, dto);
        mapper.Map(contact, dto);

        return Result<PersonalChatDto>.Success(dto);

问题出在它向我显示的映射配置文件中

var avatars = destMember ?? [];
var contactAvatar = src.CustomAvatar;

所有 props 都有正确的值，甚至返回正确的值。

1. 
2. 
3. 

但是在所有映射之后 dto 的 Avatars 字段是空列表

1. 
2. 

这是映射配置文件

CreateMap<Contact, PersonalChatDto>()
            .ForMember(dest => dest.Id,
                opt => opt.Ignore())
            .ForMember(dest => dest.FirstName, opt =>
                opt.MapFrom(src => src.CustomFirstName))
            .ForMember(dest => dest.LastName, opt =>
                opt.MapFrom(src => src.CustomLastName))
            .ForMember(dest => dest.Avatars, opt =>
                opt.MapFrom((src, _, destMember, context) =>
                {
                    var avatars = destMember ?? [];
                    var contactAvatar = src.CustomAvatar;

                    if (contactAvatar is null) return avatars;
                    
                    avatars.Add(context.Mapper.Map<AvatarDto>(contactAvatar));
                    
                    return avatars;
                }));

联系班级

public sealed class Contact : IEntity<Guid>
{
    public Guid OwnerId { get; set; }

    public User Owner { get; set; }

    public Guid UserId { get; set; }

    public User User { get; set; }

    public string CustomFirstName { get; set; }

    public string? CustomLastName { get; set; }

    public Guid CustomAvatarId { get; set; }

    public ContactAvatar? CustomAvatar { get; set; }

    public Guid Id { get; set; } = Guid.NewGuid();
}

个人聊天记录

public sealed record PersonalChatDto(
    [Required] Guid Id,
    [Required] string UserName,
    [Required] string FirstName,
    string? LastName,
    string? Biography,
    List<AvatarDto>? Avatars,
    [Required] bool IsMuted)
{
    public PersonalChatDto() 
        : this(default, default!, default!, null, null, null, default)
    {
    }
};

我试图配置地图配置文件以添加到现有项目列表，而不是设置新值。

Answer 1

您应该通过自动映射器使用 ValueResolver

CreateMap<Contact, PersonalChatDto>()
        .ForMember(dest => dest.Id,
            opt => opt.Ignore())
        .ForMember(dest => dest.FirstName, opt =>
            opt.MapFrom(src => src.CustomFirstName))
        .ForMember(dest => dest.LastName, opt =>
            opt.MapFrom(src => src.CustomLastName))
        .ForMember(dest => dest.Avatars, opt => opt.MapFrom<CustomResolver>());

Resolver 类看起来像这样

public class CustomResolver : IValueResolver<Source, Destination, int>
{
    public int Resolve(Source source, Destination destination, int member, ResolutionContext context)
    {
        return source.Value1 + source.Value2;
    }
}

您应该根据需要更改 TDestmember

您还应该将此客户解析器注册为程序中的服务。cs

builder.Services.AddTransient<CustomResolver>();


       

检查https://docs.automapper.org/en/stable/Custom-value-resolvers.html#custom-value-resolvers