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Thread ID: 68523	2006-05-02 02:04:00	VB code in Access	pico (4752)	Press F1

Post ID	Timestamp	Content	User
451324	2006-05-02 02:04:00	Hi all, I am trying to write some code to check to see whether a list box control has a value selected or not. I have some other controls on the form which modify what is displayed in the list box so sometimes there is no value selected. I want to either check to see if there is a value selected or diable a button that goes to the next form because if there is no value selected there is a problem. Private Sub ViewProject_Click() Dim Check Check = CheckHasValue(ProjectSelectWindow) Select Case Check Case "Error" MsgBox "Error" Exit Sub Case False MsgBox "Please select a project first." Exit Sub Case True CurrentProject = Form_ProjSelect.ProjectSelectWindow DoCmd.OpenForm "Proj" DoCmd.Close acForm, "ProjSelect" End Select End Sub This is what I have so far. It calls a user-defined function, CheckHasValue which checks to see if the control has a value. This is the code for that function. Public Function CheckHasValue(ObjectToCheck As Object) If ObjectToCheck = Null Then CheckHasValue = False ElseIf ObjectToCheck <> Null Then CheckHasValue = True Else CheckHasValue = "error" End If End Function I'm not sure where the problem is occuring but the function seems to be returning "error" when it is called. Any suggestions?	pico (4752)
451325	2006-05-02 02:32:00	Just quickly looking at your code it appears that you are passing the name of the form rather than the name on the control that you want to check (e.g. textbox). Try passing the control name and you should hopefully have more luck!	odyssey (4613)
451326	2006-05-02 02:50:00	Thanks Odyssy, The control name is "ProjectSelectWindow". The problem is the function is testing ProjectSelectWindow to first see if it is null then not null and else return "error" which it seems to be doing. Should I not be referring to the ProjectSelectWindow as an object?	pico (4752)
451327	2006-05-02 04:09:00	Hi Pico I think you need: Check = CheckHasValue(ProjectSelectWindow.Text) and: Public Function CheckHasValue(ObjectToCheck As String) If ObjectToCheck = "" Then CheckHasValue = False ElseIf ObjectToCheck <> "" Then CheckHasValue = True Else CheckHasValue = "error" End If End Function This will send the text value from the listbox to the CheckHasValue function as a string, which requires a slight modification in that function to check for an empty string rather than checking for an object.	Antmannz (6583)
451328	2006-05-02 22:22:00	Hi again Antmannz, Hey I tried your solution and firstly it errors saying "Method or data member not found". Referring to the .text. So I changed it to Check = CheckHasValue(ProjectSelectWindow.Value) Hoping it would then return the value in the listbox as a string. Then it errors saying "invalid use of null". Stopping at the same point. However when there is a value selected in the list box everything works fine. So the problem is occuring when trying to pass a null value to the function, is that what would cause an error?	pico (4752)
451329	2006-05-03 01:56:00	Looked at your code a bit harder this time! Basically you should be using the "isnull" function to check the list box. I'm assuming that you are limiting the list box to a know list. You should change your CheckHasValue function to be: Public Function CheckHasValue(ObjectToCheck As Object) CheckHasValue = False If IsNull(ObjectToCheck) = False Then CheckHasValue = True End Function And update your Case "Error" to be Case Else and the last item in your select statement.	odyssey (4613)
451330	2006-05-03 03:18:00	Candidly I haven't really looked over your code, but your function could use "err.clear: on error resume next" and check for error codes. I try to avoid VB in Access (or Access at all), so I could be wrong.	kingdragonfly (309)
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