在通用存储库中加载导航属性

Question

I have a problem when using AutoMapper and EF Core together to map navigation properties from the model to the DTO. My EF classes are:

public class Meal
{
    public DateTime Day { get; set; }

    public MealType MealType { get; set; }

    public int MealId { get; set; }
}

public class MealType
{
    public string Name { get; set; }

    public int MealTypeId { get; set; }
}

And the corresponding DTO classes:

public class ExistingMealDto
{
    public DateTime Day { get; set; }

    public ExistingMealTypeDto MealType { get; set; }

    public int MealId { get; set; }

    public string MealTypeName { get; set; }
}

public class ExistingMealTypeDto
{
    public string Name { get; set; }

    public int MealTypeId { get; set; }
}

This is my AutoMapper mapping:

config.CreateMap<DataLayer.EfClasses.MealType, ExistingMealTypeDto>();
config.CreateMap<DataLayer.EfClasses.Meal, ExistingMealDto>()
      .ForMember(x => x.MealType, x => x.MapFrom(x=>x.MealType))
      .ForMember(x => x.MealTypeName, x => x.MapFrom(y => y.MealType.Name));

I'm loading the data within a generic method that looks like this:

public IEnumerable<TDtoOut> GetAllAsDto<TIn, TDtoOut>()
        where TIn : class
    {
        var allEntities = DbContext.Set<TIn>();

        return Mapper.Map<IEnumerable<TDtoOut>>(allEntities);
    }

When calling this code, all Meal instances are loaded from the database and MealId and Day are filled correctly. However, MealType is null and therefore ExistingMealDto.MealType is null as well. I can work around this problem by explicitly calling DbContext.MealTypes.ToList() , but since the method should be generic for TIn , this is not a production solution.

How can I solve this issue? Thanks!

Answer 1

For getting the related data in generic method, you can judge the Type of the passed type. The following is a test demo, you could refer to:

public IEnumerable<TIn> GetAllAsDto<TIn>()
    where TIn : class
    {
        Type typeParameterType = typeof(TIn);
        if (typeParameterType == typeof(User))
        {
            var Entities = _context.Set<User>().Include(u=>u.Orders);
            return (IEnumerable<TIn>)Entities;
        }

        else
        {
            var allEntities = _context.Set<TIn>();
            return allEntities;
        }
    }

public void Test()
{
     var data = GetAllAsDto<User>();
     var data1 = GetAllAsDto<Status>();
}

Result