Excel combo box problem - vba

Question

I have a form in Excel with a combo box control. I want the values to be filled from a database table when the combo box is opened using what has already been typed in as a LIKE criteria. This is the code I have so far for the DropButtonClick event to achieve this.
Private Sub cboVariety_DropButtonClick()
Static search_text As String
Static is_open As Boolean
Dim rs As New Recordset
If is_open Then
is_open = False
Exit Sub
End If
is_open = True
If search_text = cboVariety Then Exit Sub
search_text = cboVariety
cboVariety.Clear
cboVariety.AddItem search_text
If Len(search_text) > 2 Then
rs.Open _
"SELECT Name FROM tbl_Varieties " & _
"WHERE Name LIKE '%" & search_text & "%' " & _
"ORDER BY Name", connect_string, adOpenStatic
Do Until rs.EOF
If rs!Name <> search_text Then cboVariety.AddItem rs!Name
rs.MoveNext
Loop
rs.Close
End If
End Sub
The problem is that the DropButtonClick event fires both when the combo box is opened and when it is closed. If this sub executes when the combo box is closing, the code that clears the combo box causes the user's selection to be erased.
I'm trying to tell when the box is closed using the is_open variable, which alternates between true and false each time the event sub is executed. This seems like a brittle solution to the problem. Is there a better way?

Answer 1

You are on the right track by using the is_open boolean to track the state of the combo box, but what you really want to track is the state of "should I re-populate the combo box with database data?"
When do you want the list box populated? Currently, you want the list box to be populated every time the user clicks the drop-down box (not taking into account your is_open state variable). Is this really what you want?
I would imagine that what you really want is to have the combo box only update after something else changes. Perhaps you only want the drop down list to update when the form first opens. Maybe you only want the data to change when the text in a search box changes. If this is the case, you need to base your logic on the state of when you actually want to perform the update.
For example, let's say you want to update the combo box only if the text in a search box changes. I'm not looking at Excel at the moment, but let's pretend you have a text box called txtSearch with a Text property. I'd start by adding a module or class level variable to maintain the state of the previous text entry:
Private mPreviousSearchText As String
Then I'd update my event code like so:
Private Sub cboVariety_DropButtonClick()
Dim rs As New Recordset
Dim search_text As String
search_text = txtSearch.Text
If mPreviousSearchText = search_text Then
'The current search matches the previous search,'
'so we do not need to perform the update.'
Exit Sub
End If
cboVariety.Clear
cboVariety.AddItem search_text
If Len(search_text) > 2 Then
rs.Open _
"SELECT Name FROM tbl_Varieties " & _
"WHERE Name LIKE '%" & search_text & "%' " & _
"ORDER BY Name", connect_string, adOpenStatic
Do Until rs.EOF
If rs!Name <> search_text Then cboVariety.AddItem rs!Name
rs.MoveNext
Loop
rs.Close
End If
'Set the previousSearchText var to be the search_text so that it does'
'not run unless the value of my text box changes.'
mPreviousSearchText = search_text
End Sub
The entire point is to establish when you actually want to perform the update and find out a way to tie your logic decision to the state associated with when you want to perform the action, which is only coincidentally related to the user clicking on the drop-down box.

Answer 2

I found a simple way to solve this. It doesn't seem like it should work, but if I just reassign the value of the combo box after rebuilding the list, it doesn't discard the value that is selected.
Private Sub cboVariety_DropButtonClick()
Static search_text As String
Dim rs As New Recordset
If search_text = cboVariety Then Exit Sub
search_text = cboVariety
cboVariety.Clear
If Len(search_text) > 2 Then
rs.Open _
"SELECT Name FROM tbl_Varieties " & _
"WHERE Name LIKE '%" & search_text & "%' " & _
"ORDER BY Name", connect_string, adOpenStatic
Do Until rs.EOF
cboVariety.AddItem rs!Name
rs.MoveNext
Loop
rs.Close
End If
'' Reassign cboVariety in case this event was triggered by combo close
cboVariety = search_text
End Sub

Answer 3

This worked for me, instead of assigning the value, i assign the ListIndex property.
index = cb.ListIndex
cb.Clear
while condition
cb.AddItem item
Wend
If index < cbLinia.ListCount Then
cb.ListIndex = index
Else
cb.ListIndex = -1
End If

Answer 4

Use GotFocus() instead.
Private Sub ComboBox1_GotFocus()
MsgBox "caca"
End Sub
Triggers only when the combo get focus.
HTH