From d85c420749fa7f95c897e4ee017c780e48ead831 Mon Sep 17 00:00:00 2001
From: Vincent Gao <gaobing1230@gmail.com>
Date: Thu, 25 Jun 2026 01:58:52 +0200
Subject: [PATCH] fix: %j (day of year) format directive ignored month/day in
 parse_with_formats

When a user-supplied date format contained %j (day of year), parse_with_formats
incorrectly treated the parsed date as having no month and no day. This caused
it to overwrite the correctly-parsed month and day with the current-date defaults
instead of preserving what strptime extracted.

Root cause: missing_day was computed as '"%d" not in date_format', missing %j
(and %-j) as day-of-year directives. A successful strptime with %j always
populates both the day and month fields (e.g. day 100 of 2023 = April 10).
The pre-existing _get_missing_parts helper already listed %j in the day
directive mapping but not in month.

Fix: add %j and %-j to the month directive mapping in _get_missing_parts, and
replace the ad-hoc missing_month/missing_day checks in parse_with_formats with
_get_missing_parts, which is the authoritative source for this logic.

Before:
  dateparser.parse("2023-100", date_formats=["%Y-%j"])
  -> datetime(2023, 6, 25)  # wrong: June 25 = today

After:
  dateparser.parse("2023-100", date_formats=["%Y-%j"])
  -> datetime(2023, 4, 10)  # correct: day 100 of 2023
---
 dateparser/date.py           |  6 ++++--
 dateparser/utils/__init__.py |  4 +++-
 tests/test_date.py           | 28 ++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/dateparser/date.py b/dateparser/date.py
index 094591707..cef23338b 100644
--- a/dateparser/date.py
+++ b/dateparser/date.py
@@ -14,6 +14,7 @@
 from dateparser.parser import _parse_absolute, _parse_nospaces
 from dateparser.timezone_parser import pop_tz_offset_from_string
 from dateparser.utils import (
+    _get_missing_parts,
     apply_timezone_from_settings,
     get_timezone_from_tz_string,
     set_correct_day_from_settings,
@@ -187,8 +188,9 @@ def parse_with_formats(date_string, date_formats, settings):
         except ValueError:
             continue
         else:
-            missing_month = not any(m in date_format for m in ["%m", "%b", "%B"])
-            missing_day = "%d" not in date_format
+            _missing = _get_missing_parts(date_format)
+            missing_month = "month" in _missing
+            missing_day = "day" in _missing
             if missing_month and missing_day:
                 period = "year"
                 date_obj = set_correct_month_from_settings(date_obj, settings)
diff --git a/dateparser/utils/__init__.py b/dateparser/utils/__init__.py
index 023c5fbb3..ccbe9eac5 100644
--- a/dateparser/utils/__init__.py
+++ b/dateparser/utils/__init__.py
@@ -57,7 +57,9 @@ def _get_missing_parts(fmt):
     """
     directive_mapping = {
         "day": ["%d", "%-d", "%j", "%-j"],
-        "month": ["%b", "%B", "%m", "%-m"],
+        # %j (day of year) encodes month implicitly: a successful strptime with %j always
+        # populates the month field, so %j should count as providing month information.
+        "month": ["%b", "%B", "%m", "%-m", "%j", "%-j"],
         "year": ["%y", "%-y", "%Y"],
     }
 
diff --git a/tests/test_date.py b/tests/test_date.py
index 7c8759b89..d2bd2987e 100644
--- a/tests/test_date.py
+++ b/tests/test_date.py
@@ -374,6 +374,34 @@ def test_should_parse_date(self, date_string, date_formats, expected_result):
         self.then_parsed_period_is("day")
         self.then_parsed_date_is(expected_result)
 
+    @parameterized.expand(
+        [
+            param(
+                date_string="2023-100",
+                date_formats=["%Y-%j"],
+                expected_result=datetime(2023, 4, 10),
+            ),
+            param(
+                date_string="2024-060",
+                date_formats=["%Y-%j"],
+                expected_result=datetime(2024, 2, 29),
+            ),
+            param(
+                date_string="2023 060",
+                date_formats=["%Y %j"],
+                expected_result=datetime(2023, 3, 1),
+            ),
+        ]
+    )
+    def test_should_parse_day_of_year_format(
+        self, date_string, date_formats, expected_result
+    ):
+        """Format %%j (day of year) should correctly set both month and day."""
+        self.when_date_is_parsed_with_formats(date_string, date_formats)
+        self.then_date_was_parsed()
+        self.then_parsed_period_is("day")
+        self.then_parsed_date_is(expected_result)
+
     @parameterized.expand(
         [
             param(