ExpressMapper-null到string.Empty

Question

I'm using ExpressMapper to map a Linq-To-Sql object to another object - but null values in my strings are causing issues. Is there any way to convert these null values to string.Empty from within ExpressMapper?

Eg Given the following classes:

class A
{
    string a = null;
}

class B
{
    string a;
}

When doing the conversion

B b = Mapper.Map<A, B>(new A(), new B());

I want to get ba == "" not ba == null

Answer 1

您可以使用Member功能：

Mapper.Register<A,B>().Member(dest => dest.a, src => src.a == null ? string.Empty : src.a);

Answer 2

You can use the null-coalescing operator .

string a = "";
string b = null;

string c = a ?? "xyz"; //a is not null, so empty string is assigned to c
string d = b ?? "xyz"; //b is null, so "xyz" is assigned to d

This way you can simplify your call to this:

B b = Mapper.Map<A, B>(new A(), new B());
b.a = b.a ?? "";
//"" can be String.Empty, whichever you prefer for your code style.