Object variable or With Block variable not set - Access 2010 VBA - vba

Question

Greetings to the well of knowledge...
I've been reading the numerous posts on this particular error and have not found anything that resolves my particular issue.
I have some VBA code within an Access 2010 front-end. Sometimes, but not always, I get a "Object variable or With block variable not set." error. My code is as follows:
Public Sub ValidateAddress(PassedAddress As Object, PassedCity As Object, PassedState As Object, _
PassedZIP As Object, PassedCongressionalDistrict As Object, PassedValidated As Object, HomeForm As Form)
On Error GoTo ShowMeError
Dim strUrl As String ' Our URL which will include the authentication info
Dim strReq As String ' The body of the POST request
Dim xmlHttp As New MSXML2.XMLHTTP60
Dim xmlDoc As MSXML2.DOMDocument60
Dim dbs As Database
Dim candidates As MSXML2.IXMLDOMNode, candidate As MSXML2.IXMLDOMNode
Dim components As MSXML2.IXMLDOMNode, metadata As MSXML2.IXMLDOMNode, analysis As MSXML2.IXMLDOMNode
Dim AddressToCheck As Variant, CityToCheck As Variant, StateToCheck As Variant, ZIPToCheck As Variant
Dim Validated As Boolean, District As Variant, MatchCode As Variant, Footnotes As Variant
Dim candidate_count As Long, SQLCommand As String, Start, Finish
' This URL will execute the search request and return the resulting matches to the search in XML.
strUrl = "https://api.smartystreets.com/street-address/?auth-id=<my_auth_id>" & _
"&auth-token=<my_auth_token>"
AddressToCheck = PassedAddress.Value
CityToCheck = PassedCity.Value
StateToCheck = PassedState.Value
If Len(PassedZIP) = 6 Then ZIPToCheck = Left(PassedZIP.Value, 5) Else ZIPToCheck = PassedZIP.Value
' Body of the POST request
strReq = "<?xml version=""1.0"" encoding=""utf-8""?>" & "<request>" & "<address>" & _
" <street>" & AddressToCheck & "</street>" & " <city>" & CityToCheck & "</city>" & _
" <state>" & StateToCheck & "</state>" & " <zipcode>" & ZIPToCheck & "</zipcode>" & _
" <candidates>5</candidates>" & "</address>" & "</request>"
With xmlHttp
.Open "POST", strUrl, False ' Prepare POST request
.setRequestHeader "Content-Type", "text/xml" ' Sending XML ...
.setRequestHeader "Accept", "text/xml" ' ... expect XML in return.
.send strReq ' Send request body
End With
' The request has been saved into xmlHttp.responseText and is
' now ready to be parsed. Remember that fields in our XML response may
' change or be added to later, so make sure your method of parsing accepts that.
' Google and Stack Overflow are replete with helpful examples.
Set xmlDoc = New MSXML2.DOMDocument60
If Not xmlDoc.loadXML(xmlHttp.ResponseText) Then
Err.Raise xmlDoc.parseError.errorCode, , xmlDoc.parseError.reason
Exit Sub
End If
' According to the schema (http://smartystreets.com/kb/liveaddress-api/parsing-the-response#xml),
' <candidates> is a top-level node with each <candidate> below it. Let's obtain each one.
Set candidates = xmlDoc.documentElement
' First, get a count of all the search results.
candidate_count = 0
For Each candidate In candidates.childNodes
candidate_count = candidate_count + 1
Next
Set candidates = xmlDoc.documentElement
Select Case candidate_count
Case 0 ' Bad address cannot be corrected. Try again.
Form_frmPeople.SetFocus
MsgBox "The address supplied does not match a valid address in the USPS database. Please correct this.", _
vbOKOnly, "Warning"
PassedAddress.BackColor = RGB(255, 0, 0)
PassedCity.BackColor = RGB(255, 0, 0)
PassedState.BackColor = RGB(255, 0, 0)
PassedZIP.BackColor = RGB(255, 0, 0)
Exit Sub
Case 1 ' Only one candidate address...use it and return.
For Each candidate In candidates.childNodes
Set analysis = candidate.selectSingleNode("analysis")
PassedAddress.Value = candidate.selectSingleNode("delivery_line_1").nodeTypedValue
Set components = candidate.selectSingleNode("components")
PassedCity.Value = components.selectSingleNode("city_name").nodeTypedValue
PassedState.Value = components.selectSingleNode("state_abbreviation").nodeTypedValue
PassedZIP.Value = components.selectSingleNode("zipcode").nodeTypedValue & "-" & _
components.selectSingleNode("plus4_code").nodeTypedValue
Set metadata = candidate.selectSingleNode("metadata")
PassedCongressionalDistrict.Value = CInt(metadata.selectSingleNode("congressional_district").nodeTypedValue)
PassedValidated.Value = True
Next
Exit Sub
Case Else ' Multiple candidate addresses...post them and allow the user to select.
DoCmd.SetWarnings False
Set dbs = CurrentDb
If IsTableQuery("temptbl") Then dbs.Execute "DROP TABLE temptbl"
dbs.Execute "CREATE TABLE temptbl (Selected BIT, CandidateAddress CHAR(50), CandidateCity CHAR(25), _
CandidateState CHAR(2), CandidateZIP CHAR(10), CandidateCongressionalDistrict INTEGER, _
MatchCode CHAR(1), Footnotes CHAR(30));"
DoCmd.SetWarnings True
Start = Timer
Do While Timer < Start + 1
DoEvents
Loop
For Each candidate In candidates.childNodes
Set components = candidate.selectSingleNode("components")
AddressToCheck = candidate.selectSingleNode("delivery_line_1").nodeTypedValue
CityToCheck = components.selectSingleNode("city_name").nodeTypedValue
StateToCheck = components.selectSingleNode("state_abbreviation").nodeTypedValue
ZIPToCheck = components.selectSingleNode("zipcode").nodeTypedValue & "-" & _
components.selectSingleNode("plus4_code").nodeTypedValue
Set metadata = candidate.selectSingleNode("metadata")
District = metadata.selectSingleNode("congressional_district").nodeTypedValue
Set analysis = candidate.selectSingleNode("analysis")
MatchCode = analysis.selectSingleNode("dpv_match_code").nodeTypedValue
Footnotes = analysis.selectSingleNode("dpv_footnotes").nodeTypedValue
DoCmd.SetWarnings False
dbs.Execute "INSERT INTO temptbl ( CandidateAddress, CandidateCity, CandidateState, CandidateZIP, _
CandidateCongressionalDistrict, MatchCode, Footnotes ) " & vbCrLf & "SELECT """ & AddressToCheck & _
""" AS Expr1, """ & CityToCheck & """ AS Expr2, """ & StateToCheck & """ AS Expr3, """ & _
ZIPToCheck & """ AS Expr4, " & District & " AS Expr5, """ & MatchCode & """ AS Expr6, """ & _
Footnotes & """ AS Expr7;"
DoCmd.SetWarnings True
Next
DoCmd.OpenForm "frmPeopleAddressMaintenance"
Do Until CurrentProject.AllForms("frmPeopleAddressMaintenance").IsLoaded = False
DoEvents
Loop
HomeForm.SetFocus
If IsTableQuery("temptbl") Then dbs.Execute "DROP TABLE temptbl"
End Select
dbs.Close
Exit Sub
ShowMeError:
MsgBox Err.Description, vbOKOnly, "ERROR!"
End Sub
The error occurs in two specific places:
Under the "Case 1": The error happens immediately after...
PassedCongressionalDistrict.Value = CInt(metadata.selectSingleNode("congressional_district").nodeTypedValue)
...is executed. I have debugged this and verified that the statement executed properly and that the value of the "PassedCongressionalDistrict" object is correct.
Then, under "Case Else": The For loop processes the first item list correctly, but fails with the identified error when beginning processing the second item, even though there is good and legitimate data in the second item.
I hope I've explained this well enough. I just can't seem to figure out (1) how to more fully debug this and (2) why the error occurs as it seems that I have all of my object variables defined properly.
Regards,
Ken

Answer 1

It's almost definitely because (on occasion) there is no child node member named "metadata" in the XML body - so when you try to bind your "metadata" object to the .selectSingleNode() method it returns Nothing. You can always check to make sure that it's actually bound...
'// ...start code snippet...
Set metadata = candidate.selectSingleNode("metadata")
If Not metadata is Nothing Then
PassedCongressionalDistrict.Value = CInt(metadata.selectSingleNode("congressional_district").nodeTypedValue)
End If
PassedValidated.Value = True
'// ...end code snippet...