当源之一为空时，自动映射器从多个源转换

Question

Similar to the question posted here , I would like to map multiple sources to one destination object. In my case there is possibility of few source object could be null, in that case i want automapper to map rest of the properties from other sources.

public class People {
   public string FirstName {get;set;}
   public string LastName {get;set;}
}

public class Phone {
   public string HomeNumber {get;set;}
   public string Mobile {get;set;}
}

public class PeoplePhoneDto {
    public string FirstName {get;set;}
    public string LastName {get;set;}
    public string HomeNumber {get;set;}
    public string Mobile {get;set;}
}

var people = repository.GetPeople(1);
var phone =  repository.GetPhone(4); // assume this returns null object

Mapper Config:

Mapper.CreateMap<People, PeoplePhoneDto>()
        .ForMember(d => d.FirstName, a => a.MapFrom(s => s.FirstName))
        .ForMember(d => d.LastName, a => a.MapFrom(s => s.LastName));
Mapper.CreateMap<Phone, PeoplePhoneDto>()
        .ForMember(d => d.HomeNumber, a => a.MapFrom(s => s.HomeNumber))
        .ForMember(d => d.Mobile, a => a.MapFrom(s => s.Mobile));

Extension Method:

public static TDestination Map<TSource, TDestination>(this TDestination destination, TSource source)
{
    return Mapper.Map(source, destination);
}

Usage:

var response = Mapper.Map<PeoplePhoneDto>(people)
                .Map(phone);

Now if the phone is null, response is also coming out as null . Is there any way response should contain at least values from People ?

Not sure but can we do something in the extension method:

public static TDestination Map<TSource, TDestination>(this TDestination destination, TSource source)
{
    if(source == null) //Do something;
    return Mapper.Map(source, destination);
}

Answer 1

public static TDestination Map<TSource, TDestination>(this TDestination destination, TSource source)
{
    if(source == null)
        return destination;

    return Mapper.Map(source, destination);
}