Dynamic LHH: simpler way to get typed formatted control value

[ebruchez]

Following #1342.

Say I want to show a date as part of the label, with "Quantity as of {$date}".

Right now, using "Control Value" shows "Quantity as of Tue Oct 02 17:00:00 PDT 2018", because the date doesn't use the appropriate formatting.

I can work around this with a very complicated formula:

format-date(array:get(fr:control-typed-value('date'), 1), '[MNn] [D], [Y]', 'en', (), ())

or:

format-date(xs:date(fr:control-string-value('date')), '[MNn] [D], [Y]', 'en', (), ())

We should:

• fix the default formatting so we can use "Control Value" in most cases
• allow getting control values with variables

For variables, $foo should translate to:

let $array := fr:control-typed-value('foo', false())
return
  for $i in (1 to array:size($array))
  return
    array:get($array, $i)

With this, we could do a custom formatting with:

format-date($date, '[MNn] [D], [Y]', 'en', (), ())

Even better, in the big picture, would be to have a custom formatting feature for the parameter in the Form Builder UI.