C# - 使用泛型的IDataReader到Object映射

Question

如何使用泛型将DataReader对象映射到类对象？

例如,我需要执行以下操作:

public class Mapper<T>
    {
        public static List<T> MapObject(IDataReader dr)
        {
            List<T> objects = new List<T>();

            while (dr.Read())
            {
                //Mapping goes here...
            }

            return objects;
        }
    }

后来我需要调用这个类方法,如下所示:

IDataReder dataReader = DBUtil.Fetchdata("SELECT * FROM Book");

List<Book> bookList = Mapper<Book>.MapObject(dataReder);

foreach (Book b in bookList)
{
     Console.WriteLine(b.ID + ", " + b.BookName);
}

注意,Mapper - 类应该能够映射由T表示的任何类型的对象.

Answer 1

我为此使用ValueInjecter

我正在这样做：

 while (dr.Read())
  {
      var o = new User();
      o.InjectFrom<DataReaderInjection>(dr);
      yield return o;
  }

你需要这个 ValueInjection 才能工作：

public class DataReaderInjection : KnownSourceValueInjection<IDataReader>
    {
        protected override void Inject(IDataReader source, object target, PropertyDescriptorCollection targetProps)
        {
            for (var i = 0; i < source.FieldCount; i++)
            {
                var activeTarget = targetProps.GetByName(source.GetName(i), true);
                if (activeTarget == null) continue;

                var value = source.GetValue(i);
                if (value == DBNull.Value) continue;

                activeTarget.SetValue(target, value);
            }
        }
    }