将DataRow转换为继承DataRow的自定义类 [英] Cast DataRow To Custom Class That Inherits DataRow

问题描述

美好的一天所有!!!



我有一个我正在循环的DataTable：

Good day all!!!

I have a DataTable that I'm looping through:

foreach (DataRow r in table.Rows)
{
}

我还有一个继承DataRow的类：

I also have a class that inherits DataRow:

public class OutlookDataRow : System.Data.DataRow
{
    public OutlookGridRow OutlookRow { get; set }

    public OutlookDataRow(System.Data.DataRowBuilder builder)
       : base(builder)
    {
    }
}

我如何将DataRow r转换为OutlookDataRow，因为它循环通过DataTable ???



执行任何后续抛出施法错误：

How would I go about casting DataRow r to OutlookDataRow as it loops through the DataTable???

Doing any of the follow throws a casting error:

OutlookDataRow dr = r;

OutlookDataRow dr = (OutlookDataRow)r;

OutlookDataRow dr = r as OutlookDataRow;

foreach (OutlookDataRow r in table.Rows)
{
}

推荐答案

你不能 - 你不能把继承作为系统投射up必须发明派生类中新项目的信息。因为它不知道你添加了什么或者你想用它做什么，它甚至都不会尝试。



最好的解决方案可能是定义派生类的构造函数，它将DataRow作为参数，并根据该信息构造新的OutlookDataRow。

You can't - you cannot cast "up" the inheritance tree as the system would have to "invent" information for new items in the derived class. Since it doesn't have a clue what you added or what you want to do with it, it won't even try.

The best solution is probably to define a constructor for your derived class which takes a DataRow as the parameter and constructs a new OutlookDataRow based on that information.

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