Pls can someone check my VB/XML thinking

[Jim Brown]

Hey everyone,

I've looked at XML and VB/XML tutorials 'till they're coming out my ears and I'm still quite confused. So I thought I'd tackle a trivial task to see if my understanding is OK.

I thought I'd create an XML database of People, where each Person therein has a LastName and a FirstName, thusly:

<People>
   <Person>
      <LastName>Fred</LastName>
      <FirstName>Bloggs</FirstName>
  </Person>
.... more persons
</People>

The task was to load the XML file first; that's easy and I hardcoded the data into the VB.

Then put a LastName in a textbox, and search the XML for that name. For each one found, put the corresponding FirstName in a listbox.

Criteria:

• By mistake, there may be elements other than <Person> right off the root; handle that
• The <FirstName>, <LastName> elements in a <Person> may be missing or in the wrong order; handle that
• There will likely be more than one 'FirstName' for any 'LastName; hence the listbox

My confusion came in looping thru' the nodes. Please someone check the following code to see if I've gone about this the long way round....

For each node off the root, I check it's a Person; if not it's a spurious entry.

Then in each Person, I check if there's a LastName whose text is the req'd surname from the textbox. If it is, then I check LastName's siblings to see if there's a FirstName, and if there is I bung it in the listbox.

What worries me is that this seems a very long way of doing a SELECT..... FROM..... WHERE sort of thing?

'just the part that loops thru' the nodes as described above..
 
For Each Child In xmlRoot.childNodes
  If Child.nodeName = "Person" Then
     For Each Child2 In Child.childNodes
         If Child2.nodeName = "LastName" And Child2.Text = TextLastName Then
             For Each Child3 In Child.childNodes
                If Child3.nodeName = "FirstName" Then
                 ListFirstName.AddItem Child3.Text
                End If
             Next Child3
         End If
     Next Child2
  Else
  MsgBox "Node name: " & Child.nodeName, , "Non person!"
  End If
Next Child

So any thoughts anyone?

[Mark Sreeves]

Why are Firstname and LastName sub elements of Person rather than attributes?

Each peron can only have one first name and one last name so using attributes would make it "tighter"

Or is that aspect beyond your control?

[Jim Brown]

Well Mark the whole thing's ficticious. I'm trying to get my mind around the concepts right now!

So given that yes, let's say that's the format of the data, have I gone about the ficticious task the right way?

Ta...

[Mark Sreeves]

Firstly let me confess that I've only used XML with java sax parsers

My instincts tell me that looping within the same loop doesn't seem quite right...

especially if there is only expected to be one firstname and one lastname per person.

For Each Child2 In Child.childNodes
         If Child2.nodeName = "LastName" And Child2.Text = TextLastName Then
             For Each Child3 In Child.childNodes
                If Child3.nodeName = "FirstName" Then
                 ListFirstName.AddItem Child3.Text
                End If
             Next Child3
         End If
     Next Child2

I would have thought holding the strings in a couple of variables would be better

Dim lastname As String
Dim firstname As String
For Each Child In xmlRoot.childNodes
  If Child.nodeName = "Person" Then
    For Each Child2 In Child.childNodes
      If Child2.nodeName = "LastName" Then
        lastname = Child2.Text
      End If
      If Child2.nodeName = "FirstName" Then
        firstname = Child2.Text
      End If
      
    Next Child2
    If lastname = TextLastName Then
      ListFirstName.AddItem firstname
    End If
    lastname = "": firstname = ""
    
  Else
  MsgBox "Node name: " & Child.nodeName, , "Non person!"
  End If
Next Child