fix(filters): order date range by parsed datetime, not string comparison

apps/api/plane/tests/unit/utils/test_legacy_filter_converter.py

@@ -0,0 +1,35 @@
+# Copyright (c) 2023-present Plane Software, Inc. and contributors
+# SPDX-License-Identifier: AGPL-3.0-only
+# See the LICENSE file for details.
+
+import pytest
+
+from plane.utils.filters.converters import LegacyToRichFiltersConverter
+
+
+@pytest.mark.unit
+class TestLegacyToRichFiltersConverterDateOrdering:
+    """
+    _convert_date_value must order date range bounds chronologically,
+    not lexicographically. See: https://github.com/makeplane/plane/issues/9567
+    """
+
+    def setup_method(self):
+        self.converter = LegacyToRichFiltersConverter()
+
+    def test_non_iso_date_range_is_ordered_chronologically(self):
+        # '9/1/2023' (Sep 1) < '10/1/2023' (Oct 1) chronologically, but
+        # '10/1/2023' < '9/1/2023' lexicographically ('1' < '9').
+        # The old code used string min/max and produced a reversed range.
+        result = self.converter._convert_date_value(
+            "target_date",
+            ["9/1/2023;after", "10/1/2023;before"],
+        )
+        assert result["target_date__range"] == "2023-09-01,2023-10-01"
+
+    def test_iso_date_range_still_works(self):
+        result = self.converter._convert_date_value(
+            "target_date",
+            ["2023-09-01;after", "2023-12-31;before"],
+        )
+        assert result["target_date__range"] == "2023-09-01,2023-12-31"

apps/api/plane/utils/filters/converters.py

@@ -306,8 +306,13 @@ def _convert_date_value(self, field_name: str, values: List[str], strict: bool =
         result = {}
         if len(after_dates) == 1 and len(before_dates) == 1 and len(exact_dates) == 0:
             # Simple range: one after and one before
-            start_date = min(after_dates[0], before_dates[0])
-            end_date = max(after_dates[0], before_dates[0])
+            # Parse to datetime objects so comparison is chronological, not lexicographic.
+            # String min/max only works for zero-padded ISO YYYY-MM-DD; other formats
+            # accepted by _validate_date (e.g. M/D/YYYY) would produce a reversed range.
+            after_date = dateutil_parse(after_dates[0]).date()
+            before_date = dateutil_parse(before_dates[0]).date()
+            start_date = min(after_date, before_date).isoformat()
+            end_date = max(after_date, before_date).isoformat()
             self._add_rich_filter(result, field_name, "range", [start_date, end_date])
         elif len(exact_dates) == 1 and len(after_dates) == 0 and len(before_dates) == 0:
             # Single exact date