Unmatched is a special function which returns true if the value has not matched any of the previous facets, it does not accept any arguments.
To illustrate - if there were 3 requirements, each with different priorities:
- Requirement A - Priority: High
- Requirement B - Priority: Low
- Requirement C - Priority: Medium
We could write a faceted aggregation expression:
But if we add more non-high priorities to the picklist over time, we will need to update our faceted query to then capture those values.
As an alternative we could just write this:
In this case, anything that doesn't match urgent will be "unmatched" and fall through to the "Unmatched()" facet.