c# - Automapper 不与 .MapFrom 一起使用三元和计算值与 Net Core 2.2

Question

我正在使用；

AutoMapper.Extensions.Microsoft.DependencyInjection 6.0.0

在运行 net core 2.2 的 web api 项目中

在映射我的 DTO 对象时，我使用 Automapper 来映射几个字段；

public class AutoMapperProfile : AutoMapper.Profile
{
    public AutoMapperProfile()
    {     
        CreateMap<ReviewPostInputModel, Review>()
            .ForMember(x => x.ReceiveThirdPartyUpdates, opt => opt.MapFrom(src => src.ReceiveThirdPartyUpdates ? (DateTime?)DateTime.UtcNow : null))
            .ForMember(x => x.ReceiveUpdates, opt => opt.MapFrom(src => src.ReceiveUpdates ? (DateTime?)DateTime.UtcNow : null))
            .ForMember(x => x.AverageScore, opt => opt.MapFrom(src => (decimal)Math.Round((src.Courtsey + src.Reliability + src.Tidiness + src.Workmanship) / 4, 2)));
        // ...
    }
}

在哪里；

using System;
using System.Collections.Generic;
using System.Text;

public class Review 
{
    // ...

    public decimal Reliability { get; set; }
    public decimal Tidiness { get; set; }
    public decimal Courtsey { get; set; }
    public decimal Workmanship { get; set; }

    public decimal AverageScore { get; set; }
    public DateTime? ReceiveUpdates { get; set; }
    public DateTime? ReceiveThirdPartyUpdates { get; set; }
} 

但是，当我尝试使用映射时；

var review = _mapper.Map<Review>(model);

除上面列出的我的 ForMember 外，所有标准成员都已映射，其中 DateTimes 设置为 DateTime 的新实例，Averagescore 设置为 0。

为了完整起见，我将映射器 DI 到我的 Controller 中，如下所示；

private readonly IMapper _mapper;

public ReviewController( IMapper mapper)
{
    _mapper = mapper;
}

我在 StartUp.cs 中配置 Automapper，如下所示；

services.AddAutoMapper();

我还尝试向 Controller 添加测试以确认输入的值不是问题(在映射后完成并可以确认此值已正确更新)；

review.AverageScore = (decimal)Math.Round((model.Courtsey + model.Reliability + model.Tidiness + model.Workmanship) / 4, 2);

有人知道为什么会发生这种情况吗？

Answer 1

您需要使用“ResolveUsing”而不是“MapFrom”

public class AutoMapperProfile : AutoMapper.Profile
{
    public AutoMapperProfile()
    {     
        CreateMap<ReviewPostInputModel, Review>()
            .ForMember(x => x.ReceiveThirdPartyUpdates, opt => opt.ResolveUsing(src => src.ReceiveThirdPartyUpdates ? (DateTime?)DateTime.UtcNow : null))
            .ForMember(x => x.ReceiveUpdates, opt => opt.ResolveUsing(src => src.ReceiveUpdates ? (DateTime?)DateTime.UtcNow : null))
            .ForMember(x => x.AverageScore, opt => opt.ResolveUsing(src => (decimal)Math.Round((src.Courtsey + src.Reliability + src.Tidiness + src.Workmanship) / 4, 2)));
        // ...
    }
}

你可以看看这个答案: AutoMapper: What is the difference between MapFrom and ResolveUsing?

我们过去在从“ConfigureServices”添加自动映射器时遇到过问题，可能对您来说也是如此。你可以试着把这个:

AutoMapperConfiguration.Init();

在启动函数中并添加这个类:

    using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using AutoMapper;

namespace yournamespace.ViewModels.Mappings
{
    public static class AutoMapperConfiguration
    {
        public static void Init()
        {
            Mapper.Initialize(cfg =>
            {
                cfg.CreateMap<ReviewPostInputModel, Review>()
                .ForMember(x => x.ReceiveThirdPartyUpdates, opt => opt.MapFrom(src => src.ReceiveThirdPartyUpdates ? (DateTime?)DateTime.UtcNow : null))
                .ForMember(x => x.ReceiveUpdates, opt => opt.MapFrom(src => src.ReceiveUpdates ? (DateTime?)DateTime.UtcNow : null))
                .ForMember(x => x.AverageScore, opt => opt.MapFrom(src => (decimal)Math.Round((src.Courtsey + src.Reliability + src.Tidiness + src.Workmanship) / 4, 2)));
            });
        }
    }
}