VBScript Replace specific value with regex and modify text file - vbscript

Question

I know there are a lot questions similar to this one but i couldn't find the right answer for me. I need to replace all phrases in xml file that starts and ends with % (e.g. %TEST% or %TEST-NEW% )
So far i have these tryouts:
This was my test one that works in the console but has only 1 line of string
zone = "<test>%TEST%</test>"
MsgBox zone
'Setting the regex and cheking the matches
set regex = New RegExp
regex.IgnoreCase = True
regex.Global = True
regex.Pattern = "%.+%"
Set myMatches = regex.execute(zone)
For each myMatch in myMatches
Wscript.echo myMatch
result = Replace(zone,myMatch,"")
next
MsgBox result
but when i try to do the same from a file with this...
Dim objStream, strData, fields
Set objStream = CreateObject("ADODB.Stream")
objStream.CharSet = "utf-8"
objStream.Open
objStream.LoadFromFile("C:\test\test.xml")
strData = objStream.ReadText()
Wscript.echo strData
set regex = New RegExp
regex.IgnoreCase = True
regex.Global = True
regex.Pattern = "%.+%"
Set myMatches = regex.execute(strData)
For each myMatch in myMatches
Wscript.echo myMatch
result = Replace(strData,myMatch,"")
next
Wscript.echo result
...the first echo returns correctly the contains of the file and then the second echo in the loop echoes all the matches that i need to replace , but the last echo return the same result as the first (nothing is being replaced)
The xml looks like this (just for example):
<script>%TEST%</script>
<value>%VALUE%</value>
<test>%TEST%</test>
P.S. I need to loop through xml files in a specific folder and replace the phrase from above. Can anyone help?
The final script that works for me(big thanks to Tomalak):
Option Explicit
Dim path, doc, node, placeholder,srcFolder,FSO,FLD,fil
Set placeholder = New RegExp
placeholder.Pattern = "%[^%]+%"
placeholder.Global = True
srcFolder = "C:\test"
Set FSO = CreateObject("Scripting.FileSystemObject")
Set FLD = FSO.GetFolder(srcFolder)
For each fil In FLD.Files
if LCase(FSO.GetExtensionName(fil.Name)) = "xml" Then
path = "C:\test\" & fil.Name
' 1. parse the XML into a DOM
Set doc = LoadXmlDoc(path)
' 2. select and modify DOM nodes
For Each node In doc.selectNodes("//text()|//#*")
node.nodeValue = SubstitutePlaceholders(node.nodeValue)
Next
' 3. save modified DOM back to file
doc.save path
End If
Next
' --------------------------------------------------------------------------
Function LoadXmlDoc(path)
Set LoadXmlDoc = CreateObject("MSXML2.DomDocument.6.0")
LoadXmlDoc.async = False
LoadXmlDoc.load path
If LoadXmlDoc.parseError.errorCode <> 0 Then
WScript.Echo "Error in XML file."
WScript.Echo LoadXmlDoc.parseError.reason
WScript.Quit 1
End If
End Function
' --------------------------------------------------------------------------
Function SubstitutePlaceholders(text)
Dim match
For Each match In placeholder.Execute(text)
text = Replace(text, match, GetReplacement(match))
Next
SubstitutePlaceholders = text
End Function
' --------------------------------------------------------------------------
Function GetReplacement(placeholder)
Select Case placeholder
Case "%TEST%": GetReplacement = "new value"
Case "%BLA%": GetReplacement = "other new value"
Case Else: GetReplacement = placeholder
End Select
End Function
' --------------------------------------------------------------------------

Answer 1

Never use regular expressions on XML files, period.
Use an XML parser. It will be simpler, the code will be easier to read, and most importantly: It will not break the XML.
Here is how to modify your XML document in the proper way.
Option Explicit
Dim path, doc, node, placeholder
Set placeholder = New RegExp
placeholder.Pattern = "%[^%]+%"
placeholder.Global = True
path = "C:\path\to\your.xml"
' 1. parse the XML into a DOM
Set doc = LoadXmlDoc(path)
' 2. select and modify DOM nodes
For Each node In doc.selectNodes("//text()|//#*")
node.nodeValue = SubstitutePlaceholders(node.nodeValue)
Next
' 3. save modified DOM back to file
doc.save path
' --------------------------------------------------------------------------
Function LoadXmlDoc(path)
Set LoadXmlDoc = CreateObject("MSXML2.DomDocument.6.0")
LoadXmlDoc.async = False
LoadXmlDoc.load path
If LoadXmlDoc.parseError.errorCode <> 0 Then
WScript.Echo "Error in XML file."
WScript.Echo LoadXmlDoc.parseError.reason
WScript.Quit 1
End If
End Function
' --------------------------------------------------------------------------
Function SubstitutePlaceholders(text)
Dim match
For Each match In placeholder.Execute(text)
text = Replace(text, match, GetReplacement(match))
Next
SubstitutePlaceholders = text
End Function
' --------------------------------------------------------------------------
Function GetReplacement(placeholder)
Select Case placeholder
Case "%TEST%": GetReplacement = "new value"
Case "%BLA%": GetReplacement = "other new value"
Case Else: GetReplacement = placeholder
End Select
End Function
' --------------------------------------------------------------------------
The XPath expression //text()|//#* targets all text nodes and all attribute nodes. Use a different XPath expression if necessary. (I will not cover XPath basics here, there are plenty of resources for learning it.)
Of course this solution uses regular expressions, but it does that on the text values that the XML structure contains, not on the XML structure itself. That's a crucial difference.