Closing an XML file after reading so it can be deleted - vb.net

Question

I have a problem deleting an XML file after loading it into .XMLDocument.
My code parses the XML file for specific nodes and allocates their values to variables.
Once complete the code processes data based on the values from the XML file.
This works fine until the end when i try to delete the XML file as it is still open and i then get a error "The process cannot access the file because it is being used by another process" which i guess is the XMLDocument reader.
Here is a section of the the XML processing code - this works fine.
`Dim xmlDoc As XmlDocument = New XmlDocument()
xmlDoc.Load(strFileName)
intPassed = xmlDoc.SelectSingleNode("//CalibrationPassed").InnerText
boolCheck = xmlDoc.SelectSingleNode("//ChecksComplete").InnerText
intCertRequired = xmlDoc.SelectSingleNode("//Schedule").InnerText
Console.WriteLine("Calibration Passed: " & intPassed)
Console.WriteLine("Checks Complete:" & boolCheck)
Console.WriteLine("Schedule: " & intCertRequired)
strFirstName = xmlDoc.SelectSingleNode("//FirstName").InnerText
strEMail = xmlDoc.SelectSingleNode("//Email").InnerText
strCusEmail = xmlDoc.SelectSingleNode("//CustomerEmail").InnerText
strCompanyName = xmlDoc.SelectSingleNode("//CompanyName").InnerText
strContractNumber = xmlDoc.SelectSingleNode("//ContractNo").InnerText
Console.WriteLine("First name: " & strFirstName)
Console.WriteLine("Email: " & strEMail)
Console.WriteLine("Customer EMail: " & strCusEmail)
Console.WriteLine("Company name: " & strCompanyName)
Console.WriteLine("Contract no: " & strContractNumber)
Console.WriteLine("XML Parsing Complete")
`
The code being used to delete the file is:
If System.IO.File.Exists(strFileName) = True Then
System.IO.File.Delete(strFileName)
Console.WriteLine("Deleted XML file")
End If
Any help on where I'm going wrong would be great-fully received.
Thanks

Answer 1

XmlDocument.Load uses a stream reader under the hood. There are two strategies for avoiding this:
1) A Using block will close/dispose your stream automatically and promptly
Using xmlDoc As XmlDocument = New XmlDocument()
xmlDoc.Load(strFileName)
'all of your copying stuff
End Using
'now delete your file
2) Load your XML and avoid using a reader:
Dim strXml as string
strXml = System.IO.File.ReadAllText(strFileName)
Dim xmlDoc As XmlDocument = New XmlDocument()
xmlDoc.LoadXml(strXml)
'and then the rest of your code
The downside to the 2nd approach is that my example doesn't consider any other encoding, but it should get you past your current problem. Dealing with various encoding options is a whole different matter.

Answer 2

If you're not using an xmlreader, then try this:
Dim xmlDoc = New XmlDocument()
doc.Load(strFileName)
//do all the reading stuff
Using writer = New StreamWriter(strFileName)
xmlDoc.Save(writer)
End Using
It will save your xmlDoc (in an attempt at disposing) then it should have unlocked the document which can then be deleted.
I haven't tested the code but give it a go

Answer 3

Thanks for all the help, it was being held open by streamreader which i had not considered to be a cause of the problem as I assumed it would have caused an error when XMLDocument used the file.

Answer 4

This worked for me. Setting the reference to nothing (null) to force a garbage collection.
xmlDoc = Nothing