AutoMapper map 从嵌套集合到另一个集合，其中元素需要来自源的值

Question

给定以下类和一些示例数据，有没有办法获取 Foo 的实例并创建一个 Bar 集合来获取 Foo.Id？

public class CreditsAndDebits
{
    public decimal Credits { get; set; }
    public decimal Debits { get; set; }
}

public class Foo
{
    public int Id { get; set; }
    public Dictionary<int, CreditsAndDebits> CreditsAndDebitsByYear { get; set; }
}

public class Bar
{
    public int FooId { get; set; }
    public int Year { get; set; }
    public decimal Increase { get; set; }
    public decimal Decrease { get; set; }
}

示例数据：

    var dGrohl = new Foo
    {
        Id = 13,
        CreditsAndDebitsByYear = new Dictionary<int, CreditsAndDebits>() {
        { 2019, new CreditsAndDebits { Credits = 100, Debits = 40 } } ,
        { 2020, new CreditsAndDebits { Credits = 80, Debits = 20 } } }
    };

使用以下配置，我可以将 CreditsAndDebitsByYear 字典 map 转换为“Bars”集合，但我想让 Bar.FooId 填充来自 dGrohl 的 Id 值，并且我一生都无法弄清楚该怎么做。 .

    var config = new AutoMapper.MapperConfiguration(cfg =>
    {
        cfg.CreateMap<KeyValuePair<int, CreditsAndDebits>, Bar>()
            .ForMember(dest => dest.Year, opt => opt.MapFrom(src => src.Key))
            .ForMember(dest => dest.Increase, opt => opt.MapFrom(src => src.Value.Credits))
            .ForMember(dest => dest.Decrease, opt => opt.MapFrom(src => src.Value.Debits));
    });

    var mapper = new AutoMapper.Mapper(config);

    var bars = mapper.Map<IEnumerable<KeyValuePair<int, CreditsAndDebits>>, IEnumerable<Bar>>(dGrohl.CreditsAndDebitsByYear);

Answer 1

根据@LucianBargaoanu 的评论，我可以通过执行以下操作来使其工作：

// Not necessary but for consistency
public const string FOO_ID_KEY = "FOO_ID_KEY";

    var dGrohl = new Foo
    {
        Id = 13,
        CreditsAndDebitsByYear = new Dictionary<int, CreditsAndDebits>() {
        { 2019, new CreditsAndDebits { Credits = 100, Debits = 40 } } ,
        { 2020, new CreditsAndDebits { Credits = 80, Debits = 20 } } }
    };

    var config = new AutoMapper.MapperConfiguration(cfg =>
    {
        cfg.CreateMap<KeyValuePair<int, CreditsAndDebits>, Bar>()
            // Added following line:
            .ForMember(dest => dest.FooId, opt => opt.MapFrom((src, dest, destMember, context) => context.Items[FOO_ID_KEY]))
            .ForMember(dest => dest.Year, opt => opt.MapFrom(src => src.Key))
            .ForMember(dest => dest.Increase, opt => opt.MapFrom(src => src.Value.Credits))
            .ForMember(dest => dest.Decrease, opt => opt.MapFrom(src => src.Value.Debits));
    });

    var mapper = new AutoMapper.Mapper(config);

    // added the opt=>opt.Items part below
    var bars = mapper.Map<IEnumerable<KeyValuePair<int, CreditsAndDebits>>, IEnumerable<Bar>>(dGrohl.CreditsAndDebitsByYear, opt=>opt.Items[FOO_ID_KEY] = dGrohl.Id);