An empty Date field is not '' — blank dates render as overdue
@currentField == '' does not detect an empty Date/Time field, so every item without a date falls through to the "past due" branch and lights up red — test emptiness with .displayValue, written as @currentField.displayValue in column formatting and [$FieldName.displayValue] in row formatting.
@currentField == '' u prázdného pole typu Datum neplatí, takže každá položka bez data propadne do větve „po termínu“ a zčervená – prázdnotu testuj přes .displayValue, a to zápisem @currentField.displayValue v column formattingu a [$FieldName.displayValue] v row formattingu.
Symptom
A deadline column formatted with the usual three-state logic:
"iconName": "=if(@currentField == '', '', if(@now > @currentField, 'Warning', 'Accept'))",
"txtContent": "=if(@currentField == '', '—', toLocaleDateString(@currentField))"Items that genuinely have a date render correctly. Items with an empty date show a warning icon and no text at all — and with matching row formatting, the whole row goes red as if it were badly overdue. There is no error anywhere; it just renders wrong.
Cause
For an empty Date/Time field, @currentField is not the empty string, so @currentField == '' is false and evaluation continues into the else branch. There, the empty value coerces to a timestamp at/near the epoch, which makes @now > @currentField true — every blank date is "overdue by 56 years".
The txtContent looks empty for the same reason: it takes the else branch too, and toLocaleDateString() of the empty value yields '' rather than the — you wrote.
This bites hardest on optional deadline columns, where "no date" is a normal, common state — meeting notes, templates and presentations legitimately have no review date, and they are exactly the rows that turn red.
Fix
Test emptiness on .displayValue, which is reliably '' when the field is empty — but reach for it differently in column and row formatting, because the two contexts don't accept the same syntax.
Column formatting — use @currentField.displayValue:
"iconName": "=if(@currentField.displayValue == '', '', if(@now > @currentField, 'Warning', 'Accept'))",
"txtContent": "=if(@currentField.displayValue == '', '—', toLocaleDateString(@currentField))",
"style": {
"display": "=if(@currentField.displayValue == '', 'none', 'inline')"
}[$ReviewDate.displayValue] — the bracket form — does not resolve here, even for the column's own field. It yields no value, == '' is false, and you land back in the "overdue" branch with the bug apparently unfixed.
Row / view formatting — the bracket form is the one that works, since there is no "current field":
"additionalRowClass": "=if([$ReviewDate.displayValue] == '', '', if(@now > [$ReviewDate], 'sp-css-backgroundColor-errorBackground', ''))"In both contexts .displayValue is only for the emptiness test — keep the raw field reference for the date arithmetic, because .displayValue is a locale-formatted string and useless for comparison.
Notes
- Bracket references use the internal name (
[$ReviewDate…]), not the display name — a rename otherwise silently reverts the fix. - The column/row syntax split is the easy half-fix to miss: patch the row formatter alone and the rows stop turning red while the column keeps showing a warning icon, which reads like a caching problem rather than a second bug.
- Verify with a deliberately blank item. A test set where every row has a date will never surface this, and it is invisible in the formatting pane's preview.
- The same "empty is not
''" caution applies to Person and Lookup fields, where.displayValue/.titleare likewise the dependable emptiness tests. - In view formatting, mind that
<and&can't be used at all — see View formatting JSON can't contain<or&. The reversed comparisons above are written that way on purpose.