如何使用 Automapper 映射导航属性视图模型

Question

我正在尝试使用 Automapper return 导航属性 ViewModel

型号：

public class Month

{
    public int Id { get; set; }
    public string MonthName { get; set; }
    public int YearId { get; set; }
    public Year Year { get; set; }
}

public class Year

{
    public int Id { get; set; }
    public string YearName { get; set; }
}

视图模型：

public class MonthViewModel

{
    public int Id { get; set; }
    public string MonthName { get; set; }
    Display(Name = "Financial Year")
    public int YearId { get; set; }
    public YearViewModel Year { get; set; }
}

public class YearViewModel

{
    public int Id { get; set; }
    Display(Name = "Financial Year Name")
    public string YearName { get; set; }
}

我目前有一个 ASP.NET MVC 视图映射，显示 table 中的月份列表，我需要将年份名称作为列包含在内

public  IActionResult Index()
    {

        var months =  _monthRepo.GetAll().Include(m=>m.Year);

        IEnumerable<MonthViewModel> monthsVms = MonthViewModel.MapToViewModel(months);

        return View(monthsVms);
    }



 public static IEnumerable<MonthViewModel> MapToViewModel(IEnumerable<Month> dm)
    {
        Mapper.CreateMap<Month, MonthViewModel>();
        Mapper.CreateMap<Year, YearViewModel>();
        return Mapper.Map<IEnumerable<Month>, IEnumerable<MonthViewModel>>(dm);
    }

   However in my view when I want to refer to the year name like below:


@foreach (var item in Model)
{

    @Html.EditorFor(modelItem => item.YearViewModel.YearName)

}

然而 item.YearViewModel 是 null。

问题：

如何设置 AutoMapper 以将相关导航属性 ViewModel 的模型映射到它的 ViewModel 并将其作为导航属性包含到我的 ViewModel？

主要 class 与其导航属性之间存在 1 对 0/1 的关系。例如我想显示一个月份列表，其中列月份名称和年份名称彼此相邻。（因为我只想使用 ViewModels 数据注释）

我发现了一个类似的问题 here 但是我无法让它工作

 Mapper.CreateMap<Month, MonthViewModel>().ForMember(dest => dest.YearViewModel.YearName, opt => opt.MapFrom(src => src.Year.YearName));

 Mapper.CreateMap<Year, YearViewModel>();

 return Mapper.Map<IEnumerable<Month>, IEnumerable<MonthViewModel>>(dm);

但我明白了

ArgumentException: Expression 'dest => dest.FinancialYearViewModel.FinancialYearName' must resolve to top-level member and not any child object's properties. Use a custom resolver on the child type or the AfterMap option instead. Parameter name: lambdaExpression

我尝试时遇到同样的问题

 Mapper.CreateMap<Year, YearViewModel>();
 AutoMapper.Mapper.CreateMap<Month, MonthViewModel>()
     .ForMember(a => a.YearViewModel.YearName, b => b.ResolveUsing(c => c.Year.YearName));

答案中提供的解决方案是映射整个导航属性:

Mapper.CreateMap<Year, YearViewModel>();
AutoMapper.Mapper.CreateMap<Month, MonthViewModel>()
     .ForMember(a => a.YearViewModel, b => b.ResolveUsing(c => c.Year));

Answer 1

可能这就是你想要的 -

AutoMapper.Mapper.CreateMap<Year, YearViewModel>();
AutoMapper.Mapper.CreateMap<Month, MonthViewModel>()
            .ForMember(a => a.Year, b => b.ResolveUsing(c => c.Year));
var o = AutoMapper.Mapper.Map<MonthViewModel>(new Month
            {
                Id = 1,
                MonthName = "January",
                YearId = DateTime.Now.Year,
                Year = new Year
                {
                    Id = DateTime.Now.Year,
                    YearName = DateTime.Now.Year.ToString()
                }
            }); // should map year as well.

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