如何将 DTO 对象转换为通用 T 类型

Question

i have this peace of code where i am returning a list of objects. but the return type is not allowing to return. this my interface class

interface SEC_Interface<T>
    {
        bool Add(T data);
        bool Update(T data);

        bool Delete(T data);

        List<T> GetAll();

        T GetById(int id);

        List<T> Search(string SearchTerm);
    }

Here is the method of class.My class is also generic type class and implementing this interface which is also generic.

public List<T> GetAll()
        {
            try
            {
                using (SqlConnection conn = new SqlConnection(CS))
                {
                    DataSet ds = SqlHelper.ExecuteDataset(conn, "SEC_GetAllUsers", null);

                    List<DTO_GetAll> result = ds.Tables[0].AsEnumerable()
                        .Select(dataRow => new DTO_GetAll
                        {
                          id = dataRow.Field<int>("id"),
                          FirstName = dataRow.Field<String>("FirstName"),
                            LastName = dataRow.Field<String>("LastName"),
                            Email = dataRow.Field<String>("Email"),
                            Address = dataRow.Field<String>("Address"),
                            Password = dataRow.Field<String>("Password"),
                            UserName = dataRow.Field<String>("UserName"),
                            Role_Id = dataRow.Field<int>("Role_Id"),
                            Status_Id = dataRow.Field<int>("Status_Id")
          }).ToList();

        return result;
      }
   }

Answer 1

Your implementing class can just declare the return type as List<DTO_GetAll> :

class SEC_DTO_GetAll : SEC_Interface<DTO_GetAll>
{
    public List<DTO_GetAll> GetAll()
    {

    }
}

You declare that T will be DTO_GetAll when you implement the interface.