Comment 3 for bug 697719

Based on what Jonathan and I were able to reconstruct from memory about the IRC discussion around this issue, the actual use case here is a form that has multiple inputs, which map to a single Item attribute, a reference to another Item which has the values of those inputs set on it. Unfortunately the original bug description doesn't cover this at all; I've often found it very useful to be more specific about the concrete use case that motivates a more general change, even if the benefits are "obvious".

Anyhow, I think this is the wrong way of going about things. A single item attribute should be associated with a single model parameter, which in turn should be associated with a single form input. In this particular case, there is already a (very poorly named) form input that does something like this: GroupInput. I'm not even sure if it still works, and if we're going to "resurrect" it now that somebody has a use case for it (the original code in Fusion has since been removed), perhaps it should be rewritten, but essentially what GroupInput is is a form wrapped up into an input; when the "parent" form is submitted, the "child" form is also submitted, and the result of submitting the "child" form becomes the value of the GroupInput in the "parent" form.