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QUESTION:
When the user clicks on the dropdown arrow of a comboform a list of values is presented for him to select from. When the user clicks on a value, I would like to get that value. If I use the instruction inside the OnCloseUp event:
Get Value Of oComboForm1 To sValue
I do get the old/current value. I cannot use the OnChange method because I am already using this for a different behavior.
ANSWER:
MSDN says that when a user selects a value the comboform sends two messages. These are CBN_CLOSEUP and CBN_SELCHANGE. CBN_CLOSEUP is mapped to the Visual DataFlex event OnCloseUp and CBN_SELCHANGE to the event Combo_Item_Change, which in its turn calls OnChange. MSDN also says that the order in which these two messages are sent cannot be predicted and this explains why getting the value of the comboform always returns the old value.
You can get the new value by asking the ComboForm control what the current list item is (WinCombo_Current_Item) and with this item number get the value of the N-th list item. So if we have the following OnCloseUp procedure:
Procedure OnCloseUp
Integer iItem
String sValue
Get WinCombo_Current_Item To iItem
Get WinCombo_Value iItem To sValue
End_Procedure // OnCloseUp
The string variable sValue will contain the current list value which will be placed in the form part of the comboform.
OF SPECIAL NOTE:
1. OnCloseUp is always called when the list part of the comboform is closed. This can close when you select a value but also when the ESC key is pressed. The above example does not know what you did and the messages just take the current combo list value.
2. The above answer/solution makes use of two undocumented messages. Those are not supported and may change in the future, i.e. we cannot guarantee they will be working the same way in future releases of Visual DataFlex.
3. Whenever possible use the OnChange event to react on a change in selection.
Contributed By:
Vincent Oorsprong
Company: Data Access Worldwide
email: vincent.oorsprong@dataaccess.eu
Web Site: http://www.dataaccess.eu
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