Cascading drop down in a grid

Question

Hi, 
 We have an issue with cascading drop downs within a grid. As there are two sets of drop downs which are dynamically updated within the grid. 
 However where we have multiple rows, when one drop down is set to the place holder; the related drop down where we set the ri to null will throw the error below 
 Could not display interface. Please check definition and inputs. Interface Definition: Expression evaluation error at function a!forEach [line 25]: Error in a!forEach() expression during iteration 3: Expression evaluation error at function a!dropdownField [line 71]: A dropdown component [label=&ldquo;&rdquo;] has an invalid value for &ldquo;value&rdquo;. All selected values must be present in the choiceValues array, but value was 11 and choiceValues was .

Mike Schmitt · Accepted Answer

That's nice and complicated. For debug purposes, I suggest you temporarily comment out the dropdown field for the subtype and replace it with a text field showing you the current value of ri!documentSubtypeIds. From the error message you posted initially it's clear that the dropdown is attempting to show a value even after the choiceValues for that particular location have been emptied - and therefore I suspect either that your value parameter is picking up the wrong index somehow, or your saveInto isn't really correctly removing the value from the array when the first dropdown is changed.

Mike Schmitt · Answer

It sounds like the dropdown causing the error is having its choices removed (via 'cascading' i assume), but not having its value cleared first. You will need to manually correct for this in one of a few possible ways.

Mike Schmitt · Answer

Have you double-checked that you're setting the value of the correct variable to null? Also, have you double-checked that the dropdown field in question has a placeholder defined, as the error would also happen if there's no placeholder? 
 
Various possibilities include: 
1) setting the value of the variable in question to null() in your saveInto 
2) simply not showing the dropdown field in question when the value of the next-higher-up dropdown is not set 
3) probably some others that i'm not thinking of at the moment and/or depend on the exact scenario 
 
As the earlier comments mentioned, we can help you a lot better if you provide the code section you're working with - otherwise there's no real way to help check for errors etc.