validation of values in value list

[CDiez]

Hi,

If I have a 3-tiered conditional value list, how do I prevent users from selecting invalid combinations (or how do I prevent them from being displayed in the first place)? Example: in a state-county-city hierarchy, the user selects the state, and the counties field (drop down) only shows counties in that state, then the city field only shows cities in the county selected.

I think I have the relationships right, because my drop down lists are showing the appropriate choices. However, if I select a state and county, then change the state, the county selected remains (an invalid combination, like state=New York and county=Orange).

Can someone suggest a simple way to cause the county field to revert to a blank when the state is changed, and the city field to revert when the county or state are changed?

Thanks in advance!!

Carlos

[comment]

See:

http://fmforums.com/forum/showtopic.php?tid/187106/

[CDiez]

This seems like it fits the bill exactly.

Thanks!!

[CDiez]

Do you know of anyone has implemented this solution for a three-level hierarchy? I have a need for this in two places. One is to allow users to select property types (category > type > subtype), and the other to let them select zoning code by municipality and county (county > municipality > zoning code). It would work identically though.

I'm having a little trouble figuring out how to add the 3rd level of the hierarchy into the "clear fields" solution you pointed me to.

Thanks again,

Carlos

[comment]

The same principle can be applied to three (or more) levels. Simply check if the previous levels match the current selection.