Delete a specific XML Element

Question

I'd like to delete a whole "TableData" Elemt with a specific ID (ID 10 in this case) from my xml:

<DataPaths>
  <TableData>
    <ID>10</ID>
    <TablePath>C:\Users\Tom\Test.xls</TablePath>
    <TableName>TestName</TableName>
    <Mode>TestMode</Mode>
  </TableData>
</DataPaths>

I tried two different solutions and I think I'm almost there.

Solution 1:

Dim XmldocDel As New XmlDocument()
        XmldocDel.Load("" & buildSettingsPath)
        Dim node As XmlNode
        node = XmldocDel.SelectSingleNode("//DataPaths/TableData[ID = '10']")

        If MessageBox.Show("Are you sure you want to delete:", MessageBoxButtons.YesNo) = DialogResult.Yes Then
            If node IsNot Nothing Then
            node.ParentNode.RemoveChild(node)
            'node.ParentNode.RemoveAll()

            XmldocDel.Save("" & buildSettingsPath)
            Reload()
        Else
            MessageBox.Show("No node found")
        End If

        Else
            Exit Sub
        End If

I'm getting a null Exception here.

Solution 2:

Dim clientNodes = XmldocDel.SelectNodes("//ID")
        For Each elem As Xml.XmlElement In clientNodes
            If elem.InnerText = "10" Then
                elem.ParentNode.RemoveChild(elem)
                Exit For
            End If
        Next

This will simply do nothing.

TomWayne · Accepted Answer · 2014-10-19 13:45:13Z

3

Using solution 1, since you want to delete the whole TableData element, the XPath should've selected TableData element instead of ID element :

.....
node = XmldocDel.SelectSingleNode("//DataPaths/TableData[ID = '10']")
.....

*) updated above XPath a bit. Looking at the XML posted, the first step should be DataPaths instead of DataSetPaths.

UPDATE :

Your actual XML has default namespace. So in this case, you need to register a prefix mapped to the default namespace URI using XmlNamespaceManager. Use the registered prefix in the XPath, and pass the namespace manager as 2nd parameter of SelectSingleNode() method :

Dim nsManager As New XmlNamespaceManager(New NameTable())
nsManager.AddNamespace("d", "http://tempuri.org/DataPaths.xsd")
.....
node = XmldocDel.SelectSingleNode("//d:DataPaths/d:TableData[d:ID = '10']", nsManager)
.....

[.NET fiddle demo]

edited Oct 19, 2014 at 13:45

TomWayne

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answered Oct 18, 2014 at 14:17

har07

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6 Comments

Tomalak Over a year ago

@TomWayne This code will certainly not result in a null exception. Your unchecked use of node one line later however would. Your fault, never use variables that can be null without checking if they are valid.

TomWayne Over a year ago

Was a pasting mistake by myself (the path should be correct) see updated question. Now it gives me the MessageBox "No node found"

har07 Over a year ago

@TomWayne Your actual XML must have significant difference from the one posted here (I suspect it has default namespace?). The code should work against XML posted here, see the demo : dotnetfiddle.net/ZTvcIT

har07 Over a year ago

xmlns="tempuri.org/DataPaths.xsd" is the default namespace. check updated answer for one possible solution

TomWayne Over a year ago

updated comment: @har07 I also think so....even this code will select nothing: 'node = XmldocDel.SelectSingleNode("/DataPaths/TableData[1]/ID")' the xml begins with: '<?xml version="1.0" standalone="yes"?> <DataPaths xmlns="tempuri.org/DataPaths.xsd">' I also have to admit that I am completly new to VB and working with XML Data. I never understood why the namespace only works with that content. Do I even have to use the namespace?

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