如何设置匹配属性名称为字符串集合的配置约定？

Question

I have two models:

public class UserModel
{
    public Guid Id { get; set; }
    public string Name { get; set; }
    public string NetId { get; set; }
    public string Email { get; set; }
    public string Departments { get; set; }
    public string Titles { get; set; }
}


public class UserReport : Entity
{
    public string Name { get; set; }
    public string NetId { get; set; }
    public string Email { get; set; }
    public List<string> Departments { get; set; }
    public List<string> Titles { get; set; }
}

And as such I can write my automapper mapping like this:

CreateMap<UserReport, UserModel>()
            .ForMember(x => x.Departments, x => x.MapFrom(y => string.Join("\n", y.Departments)))
            .ForMember(x => x.Titles, x => x.MapFrom(y => string.Join("\n", y.Titles)));

However, I don't want to do this for every instance of this, because this approach is going to be used on pretty much every POCO to DTO conversion. Is there a way I can write a convention in the config to check if the destination property name is of type string and it matches a property on the source type of list<string> to do the string join?

Answer 1

Mappings can nest so you just define an additional map for List<string> to string :

CreateMap<List<string>, string>().ConvertUsing(strings => {
    if (strings != null)
      return string.Join("\n", strings);
    return "";
});