Question

I have 3 entity: Obj1, Obj2, Obj3

How to map 3 entity to one with automapper?

Answer 1

This post describes how to map multiple objects into a single new object, using the following helper class:

public static class EntityMapper
{
    public static T Map<T>(params object[] sources) where T : class
    {
        if (!sources.Any())
        {
            return default(T);
        }

        var initialSource = sources[0];

        var mappingResult = Map<T>(initialSource);

        // Now map the remaining source objects
        if (sources.Count() > 1)
        {
            Map(mappingResult, sources.Skip(1).ToArray());
        }

        return mappingResult;
    }

    private static void Map(object destination, params object[] sources)
    {
        if (!sources.Any())
        {
            return;
        }

        var destinationType = destination.GetType();

        foreach (var source in sources)
        {
            var sourceType = source.GetType();

            Mapper.Map(source, destination, sourceType, destinationType);
        }
    }

    private static T Map<T>(object source) where T : class
    {
        var destinationType = typeof(T)
        var sourceType = source.GetType();

        var mappingResult = Mapper.Map(source, sourceType, destinationType);

        return mappingResult as T;
    }
}  

Simple usage:

var personViewModel = EntityMapper.Map<PersonViewModel>(person, address, comment);