From cf7537453b29acd67ccf91142baf6fc59a2088a9 Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Sun, 19 May 2024 01:33:20 +0200
Subject: [PATCH] QgsDateTimeEdit: convert datetime to UTC when format string
 includes a Z

Fixes #57262
---
 src/gui/editorwidgets/qgsdatetimeedit.cpp        |  3 +++
 src/gui/editorwidgets/qgsdatetimeeditconfig.cpp  | 12 ++++++++++++
 src/gui/editorwidgets/qgsdatetimeeditwrapper.cpp |  6 ++++++
 tests/src/python/test_qgsdatetimeedit.py         | 12 ++++++++++++
 4 files changed, 33 insertions(+)

diff --git a/src/gui/editorwidgets/qgsdatetimeedit.cpp b/src/gui/editorwidgets/qgsdatetimeedit.cpp
index 20f58ca51e2d..3cdbb4200f73 100644
--- a/src/gui/editorwidgets/qgsdatetimeedit.cpp
+++ b/src/gui/editorwidgets/qgsdatetimeedit.cpp
@@ -346,6 +346,9 @@ void QgsDateTimeEdit::setDateTime( const QDateTime &dateTime )
   {
     // changed emits a signal, so don't allow it to be emitted from setDateTime
     mBlockChangedSignal++;
+    // We need to set the time spec of the set datetime to the widget, otherwise
+    // the dateTime() getter would loose edit, and return local time.
+    QDateTimeEdit::setTimeSpec( dateTime.timeSpec() );
     QDateTimeEdit::setDateTime( dateTime );
     mBlockChangedSignal--;
     changed( dateTime );
diff --git a/src/gui/editorwidgets/qgsdatetimeeditconfig.cpp b/src/gui/editorwidgets/qgsdatetimeeditconfig.cpp
index 0a2da04e2731..db4f566b748c 100644
--- a/src/gui/editorwidgets/qgsdatetimeeditconfig.cpp
+++ b/src/gui/editorwidgets/qgsdatetimeeditconfig.cpp
@@ -411,6 +411,18 @@ QgsDateTimeEditConfig::QgsDateTimeEditConfig( QgsVectorLayer *vl, int fieldIdx,
 
 void QgsDateTimeEditConfig::updateDemoWidget()
 {
+  // Use a UTC datetime if the format string includes a Z
+  if ( mDisplayFormatEdit->text().indexOf( "Z" ) > 0 )
+  {
+    mDemoDateTimeEdit->setTimeSpec( Qt::UTC );
+    mDemoDateTimeEdit->setDateTime( QDateTime::currentDateTimeUtc() );
+  }
+  else
+  {
+    mDemoDateTimeEdit->setTimeSpec( Qt::LocalTime );
+    mDemoDateTimeEdit->setDateTime( QDateTime::currentDateTime() );
+  }
+
   mDemoDateTimeEdit->setDisplayFormat( mDisplayFormatEdit->text() );
   mDemoDateTimeEdit->setCalendarPopup( mCalendarPopupCheckBox->isChecked() );
 }
diff --git a/src/gui/editorwidgets/qgsdatetimeeditwrapper.cpp b/src/gui/editorwidgets/qgsdatetimeeditwrapper.cpp
index 817b9d11756e..3e3f641e1f91 100644
--- a/src/gui/editorwidgets/qgsdatetimeeditwrapper.cpp
+++ b/src/gui/editorwidgets/qgsdatetimeeditwrapper.cpp
@@ -271,6 +271,12 @@ void QgsDateTimeEditWrapper::updateValues( const QVariant &value, const QVariant
 
   if ( mQgsDateTimeEdit )
   {
+    // Convert to UTC if the format string includes a Z
+    if ( mQgsDateTimeEdit->displayFormat().indexOf( "Z" ) > 0 )
+    {
+      dateTime = dateTime.toUTC();
+    }
+
     mQgsDateTimeEdit->setDateTime( dateTime );
   }
   else
diff --git a/tests/src/python/test_qgsdatetimeedit.py b/tests/src/python/test_qgsdatetimeedit.py
index b3ff7892d0b7..3d22ec221cd7 100644
--- a/tests/src/python/test_qgsdatetimeedit.py
+++ b/tests/src/python/test_qgsdatetimeedit.py
@@ -17,6 +17,7 @@
 start_app()
 
 DATE = QDateTime.fromString('2018-01-01 01:02:03', Qt.DateFormat.ISODate)
+DATE_Z = QDateTime.fromString('2018-01-01 01:02:03Z', Qt.DateFormat.ISODate)
 
 
 class TestQgsDateTimeEdit(QgisTestCase):
@@ -32,6 +33,17 @@ def testSettersGetters(self):
         w.setDateTime(QDateTime())
         self.assertEqual(w.dateTime(), DATE)
 
+    def testSettersGetters_DATE_Z(self):
+        """ test widget handling with Z time spec """
+        w = QgsDateTimeEdit()
+        w.setAllowNull(False)
+
+        w.setDateTime(DATE_Z)
+        self.assertEqual(w.dateTime(), DATE_Z)
+        # date should remain when setting an invalid date
+        w.setDateTime(QDateTime())
+        self.assertEqual(w.dateTime(), DATE_Z)
+
     def testNullValueHandling(self):
         """ test widget handling of null values """
         w = QgsDateTimeEdit()