VB.NET XML Search, Read, Write.

[coleman01]

Hi,
Im trying to search through an XML file. When it finds the record it needs it then updates a specific field in that record. I have made it find the specified record but do not know how to update it and write it back to file. I am new to XML coding. Any help would be most appreciated.

Dim xpathDoc As XPathDocument
Dim xmlNav As XPathNavigator
Dim xmlNI As XPathNodeIterator
Dim filePath As New OpenFileDialog

filePath.ShowDialog()
xpathDoc = New XPathDocument(filePath.FileName)
xmlNav = xpathDoc.CreateNavigator()
xmlNI = xmlNav.Select("/Message/Pupils/PupilCode")

While (xmlNI.MoveNext())
System.Console.WriteLine(xmlNI.Current.Name + " : " + xmlNI.Current.Value)

If (xmlNI.Current.Value) = "A123981456002" Then

'ONCE ITS FOUND THE RECORD - DISPLAY A MESSAGE
'SELECT THE DIFFERENT FIELD WITHIN THE RECORD
MsgBox("Found")
xmlNav.Select("/Message/Pupils/PupilAge")
'THIS IS WHERE IT NEEDS TO UPDATE IT. NO IDEA HOW TO DO THIS BIT
End If
End While


This may be the wrong way to do it - I'm not sure. I just need it to search for a specific pupil ID and update their age with a specified value. After that it has to write the entire XML file to a new file.

Many thanks.
Chris

 

[levyuk]

You can do this by using a dataset. you can read an xml file into a dataset and then search the dataset for your field. once you have found it you can edit it and write the changes back to the xml file.

 [size=2]
[/size][size=2][color=#0000ff]Dim[/color][/size][size=2] ds [/size][size=2][color=#0000ff]As[/color][/size][size=2] DataSet = [/size][size=2][color=#0000ff]New[/color][/size][size=2] DataSet()

[/size][size=2][color=#0000ff]Dim[/color][/size][size=2] dv [/size][size=2][color=#0000ff]As[/color][/size][size=2] DataView

[/size][size=2][color=#0000ff]Dim[/color][/size][size=2] id [/size][size=2][color=#0000ff]As[/color][/size][size=2] [/size][size=2][color=#0000ff]Integer[/color][/size]
[size=2][color=#0000ff][/color][/size] 
[size=2][color=#0000ff][size=2]ds.ReadXml(Server.MapPath([/size][size=2][color=#800000]"XMLFile.xml"[/color][/size][size=2]))

dv = ds.Tables(0).DefaultView

dv.Sort = [/size][size=2][color=#800000]"id"[/color][/size]
[size=2][color=#800000][size=2]id = dv.Find(TextBoxID.Text)
[size=2]ds.Tables(0).Rows(id).Item([/size][size=2][color=#800000]"Name"[/color][/size][size=2]) = TextBoxName.Text

ds.WriteXml(Server.MapPath([/size][size=2][color=#800000]"XMLFile.xml"[/color][/size][size=2]))

[/size][/size][/color][/size][/color][/size]

I hope that helps. If not let me know because i've just cut that out of my code.

 

[coleman01]

Hi,

Thank you very much for your quick response. I thought about using a dataset but the xml file has nested relations with the same name and I just get an error ("the same table (tableName) cannot be the child table in two nested relations"). I cant really rename the other tables as it is a structured file that is set and cannot be realistically changed.

If you have any ideas that I can use to get around this I would be REALLY grateful.

Many thanks.
Chris