<a>当a＆b使用LINQ具有类似签名时，可以列出类型转换</a>

Question

I'm having some basic problem with linq, I tried to google but didn't get the desired reuslt.

Lets say We have two class with almost similar signature like these:

public class A
    {
        public int a { get; set; }
        public int b { get; set; }
        public int c { get; set; }
    }

    public class B
    {
        public int x { get; set; }
        public int y { get; set; }
        public int z { get; set; }
    }

Here A is data context class which is generated by the framework while creating the .edmx file & B is my custom class to carry data to UI. I'm querying the data base using A & getting a iqueryable list. Now I need to convert this list into another list of type B. How can I do that?

Answer 1

You need to use Select to project from one type to another, then ToList to create a list:

// Property names changed to follow .NET naming conventions
var list = query.Select(a => new B { X = a.A, Y = b.B, Z = c.C })
                .ToList();

The compiler and runtime wouldn't care if your types had the same properties (not that they do in this case - they have different names) - they're still entirely separate types.

Answer 2

Assume your query method returns an IEnumerable<A> you can do the following.

IEnumerable<A> myList = SomeMethod();

var myModelList = myList.Select(a => new B(){x = a.A, y = a.B, z = a.C});

Answer 3

You will use projections when selecting.

var myQuery = (from a in context.A
              select new B{
                  x = a.A,
                  y = a.B,
                  z = a.C
               });

return myQuery.ToList();