DocumentElement.AppendChild抛出未设置为对象实例的对象引用 [英] DocumentElement.AppendChild throws object reference not set to an instance of an object

问题描述

我试图创建一个新的xml文件，将数据写入并保存。

I'm trying to create a new xml file, write data into it and than save.

这里是代码：

XmlDocument doc= new XmlDocument();
XmlDeclaration dec = doc.CreateXmlDeclaration("1.0", null, null);
doc.AppendChild(dec);

XmlElement rootnode = doc.CreateElement("Root");

foreach (var item in list)
{
   XmlElement parent = ordersNIA.CreateElement("ParentElement");

   XmlElement childOne = ordersNIA.CreateElement("childOne");
   childOne.InnerText = "This is the first child";
   parent.AppendChild(childOne);

   XmlElement childTwo = ordersNIA.CreateElement("childTwo");
   childOne.InnerText = "This is the second child";
   parent.AppendChild(childTwo);

   XmlElement childThree = ordersNIA.CreateElement("childThree");
   childOne.InnerText = "This is the third child";
   parent.AppendChild(childThree);

   rootnode.AppendChild(parent);

}

doc.DocumentElement.AppendChild(rootnode);
doc.Save("xmlDocument.xml");

doc.DocumentElement.AppendChild（rootnode）; 是抛出

对象引用未设置为对象实例的行

"object reference not set to an instance of an object"

我一直在互联网上，但我似乎找不到一个答案为什么这个错误被抛出。

I've been looking on internet but I don't seem to find an answer to why this error is being thrown.

当我检查rootnode时，我看到它的innerHTML完全填充了我的xml，所以似乎是正确的。我没有看到任何空对象，但也许我错过了一些东西。

When I check the rootnode I see it's innerHTML completely filled with my xml so that seems to be correct. I don't see any null-objects but maybe I'm missing something

任何帮助是非常赞赏。

推荐答案

你还没有文档元素，因为你添加的唯一的孩子是一个声明。替换

You haven't document element yet, because the only child you've been added is a declaration. Replace

doc.DocumentElement.AppendChild(rootnode);

其中：

doc.AppendChild(rootnode);

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