创建通用存储库 <T> 用反射

Question

How can I create a repository object for a custom object? I don't know the CustomEntity type when I am creating repo object.

I am trying something below.

var _unitofWork = new UnitOfWork();
var objRepository = new Repository<Type.GetType("EntityName")>(_unitofWork);

Can anyone help with this?

Answer 1

You cannot reasonably create a Repository for any arbitrary type.

If the objects need have nothing in common, the repository code would not know how to treat them. How would you write code to handle Customer, ComplexNumber, and System.Object?

If the objects you are concerned with do have enough in common to be able to treat them in a common manner, express that commonality with a common base class or with an interface that they all implement. Then you can do

var rep = new Repository<IMyCommonalities>(_unitOfWork);

Answer 2

You can create a generic object at runtime by using MakeGenericType and Activator

var _unitofWork = new UnitOfWork();
var objRepository = Activator.CreateInstance(typeof(Repository<>).MakeGenericObject(Type.GetType("EntityName")), _unitofWork);

The only problem is that Activator.CreateInstance returns an object. There is no easy way to access any member without a common interface of all generic types. Maybe you have an interface like IRepository that doesn't need a generic which you can work with. In that case cast the return value of CreateInstance to it. If you don't have such an interface you have to use reflection or dynamic what leeds to runtime errors if you call an invalid member.