Question

I m 在现有XML doc中添加一个内容,其代码如下:

        Dim theXMLSource As String = Server.MapPath("~/Demo/") & "LabDemo.xml"
    Dim nodeElement As XElement

    Dim attrAndValue As XElement = _
        <LabService>
            <ServiceType>
                <%= txtServiceType.Text.Trim %>
            </ServiceType>
            <Level>
                <%= txtLevel.Text.Trim %>
            </Level>
        </LabService>

    nodeElement.Add(New XElement(attrAndValue))
    nodeElement.Save(theXMLSource)

这是错误的:

System.NullReferenceException: Object reference not set to an instance of an object.

Object reference not set to an instance of an object.

Error line: nodeElement.Add(New XElement(attrAndValue))

我 it倒了这一错误,但我却拿不出错误。你们能否表明问题是什么? 谢谢。

Answer 1

你们需要装上现有的档案,例如:

Dim theXMLSource As String = Server.MapPath("~/Demo/LabDemo.xml")
Dim document As XDocument = XDocument.Load(theXMLSource)

...

document.Root.Add(attrAndValue)
document.Save(theXMLSource)

Answer 2

您定义内容,但随后在请你说明其方法之前不会立即进行。

Answer 3

首先需要:

Dim nodeElement As New XElement

Answer 4

“Dim nodeElement As New XElement”

实际上,新式并非要素的有效方法。即使它穿透了 de(我怀疑是这样),它也会导致卸载。

和S Laks一样,你可以打开现有的档案(我认为档案可能像你在岗位上所说的那样存在)。

你们要么可以使用

document.Root.Add(attrAndValue)

或

Dim nodeElement As XElement = document.<theXMLroot>(0)

nodeElement.Add(attrAndValue)

之后

document.Save(theXMLSource)

both w或k the same way. since you re using literals, I thought you might want to know the "second way" It s useful mainly because you can change to the where you want to insert the element.

f或 instance

Dim nodeElement As XElement = document.<theXMLroot>.<parent>(0)

或

Dim nodeElement As XElement = document...<parent>(0)

希望它有助于

友情链接