Specifying AutoMapper mappings based on list of properties

Question

Hello fellow overflowers,

I'm not sure if it is even possible or I'm fighting against the windmills but what I would like to accomplish is sort of generic mapper based on AutoMapper.

Using this mapper I would be able to specify some types to be mapped and both source and destination types will be the same.

Then I would like to provide a list of properties as a param to method which would specify a subset of all properties on particular type.

So calling a method would look like this:

Given following method signature

public T Map<TProp>(T source1, T source2, params Expression<Func<T,TProp>>[] propsToMap)

amm stands for AutoModelMapper.

amm.Map<>(
        adminFeeSource,
        adminFeeDestination,
        fee => fee.FeeAmount,
        fee => fee.NoValueMessage);

How to achieve that in safe way (using generics)? Is that even possible?

Kind regards

Answer 1

I don't understand your question TBH since AFAIK you need to register your mappings for AutoMapper to work based on its documentation, but see if this will help you.

Use a static Mapper

public class MapperConfig
{
    public static MapperConfiguration MapperCfg { get; private set; }
    public static IMapper Mapper { get; private set; }

    public static void RegisterMappings()
    {
        MapperCfg = new MapperConfiguration(cfg =>
        {
            cfg.AllowNullCollections = true;
            cfg.AllowNullDestinationValues = true;

            #region Entity VMs

            cfg.CreateMap<Address, AddressVM>().MaxDepth(3).ReverseMap();
            cfg.CreateMap<ApplicationUserConfig, ApplicationUserConfigVM>().MaxDepth(3).ReverseMap();
            // ... You need to define the objects in the mapper config
            cfg.CreateMap<WarehouseConfig, WarehouseConfigVM>().MaxDepth(3).ReverseMap();

            #endregion
        });

        Mapper = MapperCfg.CreateMapper();
    }
}

On your application startup call MapperConfig.RegisterMappings(); to register the model mappings.

Then you can create an extension

public static class Extension
{
    public static IPagedList<TDestination> ToMappedPagedList<TSource, TDestination>(this IPagedList<TSource> list)
    {
        IMapper mapper = MapperConfig.Mapper;

        IEnumerable<TDestination> sourceList = mapper.Map<IEnumerable<TDestination>>(list);
        IPagedList<TDestination> pagedResult = new StaticPagedList<TDestination>(sourceList, list.GetMetaData());

        return pagedResult;
    }

    public static IEnumerable<TDestination> Map<TSource, TDestination>(this IEnumerable<TSource> list)
        where TSource : class
        where TDestination : class, new()
    {
        IMapper mapper = MapperConfig.Mapper;

        IEnumerable<TDestination> sourceList = mapper.Map<IEnumerable<TDestination>>(list);

        return sourceList;
    }

    public static TDestination Map<TSource, TDestination>(this TSource entity)
        where TSource : class
        where TDestination : class, new()
    {
        IMapper mapper = MapperConfig.Mapper;

        return mapper.Map<TDestination>(entity);
    }
}

Ideally you would register your IMapper in an IoC Container and not call MapperConfig.Mapper directly in your Extention.cs but this will do for the example.

Usage:

Address address = new Address();
AddressVM = address.Map<Address, AddressVM>();