General

Re: Returning the Display name from a drop down list box

Jimmy — Tue, 13 Oct 2009 23:27:16 GMT

Like I already said, unless for every AssignID value in the table, there is a row with an EmpID that has that value, that code is going to cause an "Object reference not set to an instance of an object." error.

I can't really tell what that code is trying to accomplish. Could you explain a bit what you are trying to do?

Re: Returning the Display name from a drop down list box

sshines — Tue, 13 Oct 2009 13:38:20 GMT

I changed my code to look like your sample above and I am receiving the error "Object reference not set to an instance of an object.". The variable Value contains my @EmpID value and @FullNameLast also has a value. Why am I getting this error?

Dim root As XPathNavigator = DataSources("v_WHAllEmpsBlueBook").CreateNavigator()

Dim iter As XPathNodeIterator = root.Select("//dfs:myFields/dfs:dataFields/d:v_WHAllEmpsBlueBook/d:EmpAssistants/@AssignID", NamespaceManager)

Dim sb As New System.Text.StringBuilder

Dim value As String

Dim strValue As String

While (iter.MoveNext())

value = iter.Current.Value

strValue = root.SelectSingleNode("//dfs:myFields/dfs:dataFields/d:v_WHAllEmpsBlueBook/d:EmpAssistants[@EmpID = '" + value + "']/@FullNameLast", NamespaceManager).Value

End While

Re: Returning the Display name from a drop down list box

Jimmy — Tue, 13 Oct 2009 13:21:40 GMT

This part of your XPath:

...@AssignID[@EmpID = '" + value + "']/@FullNameLast

reads as "retrieve the FullNameLast attribute belonging to the AssignID attribute that has an EmpID attribute with the value value," but it's not possible for attributes to possess other attributes, so that is part of your problem. My guess is you want something like

...d:EmpAssistants[@EmpID = '" + value + "']/@FullNameLast

Also, unless you're absolutely sure that your .SelectSingleNode() is always going to find a match, you shouldn't reference its .Value without first checking that it's not null (or Nothing in VB speak). If it is, you're going to wind up with null reference exceptions.

Returning the Display name from a drop down list box

sshines — Tue, 13 Oct 2009 13:08:39 GMT

Here is my code. It is erroring on the line in bold and I don't know why. My Value is being properly returned as the value in my listbox. I cannot return the Display Name.

Dim root As XPathNavigator = DataSources("v_WHAllEmpsBlueBook").CreateNavigator()

Dim iter As XPathNodeIterator = root.Select("//dfs:myFields/dfs:dataFields/d:v_WHAllEmpsBlueBook/d:EmpAssistants/@AssignID", NamespaceManager)

Dim sb As New System.Text.StringBuilder

Dim value As String

Dim strValue As String

While (iter.MoveNext())

value = iter.Current.Value

strValue = root.SelectSingleNode("//dfs:myFields/dfs:dataFields/d:v_WHAllEmpsBlueBook/d:EmpAssistants/@AssignID[@EmpID = '" + value + "']/@FullNameLast", NamespaceManager).Value

End While