I have two date fields, the first is a START_DATE and the second is an END_DATE.
Both are combo box (drop down). In the Combo Box Properties, under the Options tab, the Item List for both fields contain the same values (only Wednesdays are listed formatted as 2011/04/27).
When a START_DATE value is selected by the user, I want the END_DATE field to be updated to the same value. This is easily done using the guidance on this site using Thom Parker's tutorial named Changing Another Field with Combo Box (Drop Down) Selection.
The question is, can the END_DATE field later be changed to a different date selected from the drop down list of END_DATE.
There are a couple of approaches to implementing this. One solution is to use a calculation script on END_DATE in combination with a state machine to ensure that the source is chosen properly. This approach is overly complex and has reliability issues.
The easiest and most reliable solution is to use the change or format events on START_DATE to set the value of END_DATE. The user can then make a selection on END_DATE without any interference, or odd event issues from the START_DATE field. The user can only use one control on the form at a time so they are either setting the value of START_DATE or END_DATE. With this implementation the action of setting the END_DATE is does not cause any scripting conflicts. But you have the problem of a START_DATE selection always overriding the END_DATE. There is a solution to this issue, Set a boolean variable when the user makes a selection on END_DATE, then use this variable to block the action from START_DATE.
Thom Parker
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