Fix Date timezone handling for PostgreSQL PreferSimpleProtocol

date.go

@@ -17,7 +17,7 @@ func (date *Date) Scan(value interface{}) (err error) {
 
 func (date Date) Value() (driver.Value, error) {
 	y, m, d := time.Time(date).Date()
-	return time.Date(y, m, d, 0, 0, 0, 0, time.Time(date).Location()), nil
+	return time.Date(y, m, d, 0, 0, 0, 0, time.UTC), nil
 }
 
 // GormDataType gorm common data type

date_timezone_test.go

@@ -0,0 +1,88 @@
+package datatypes_test
+
+import (
+	"testing"
+	"time"
+
+	"gorm.io/datatypes"
+)
+
+func TestDateTimezoneHandling(t *testing.T) {
+	// Test that Date.Value() returns consistent results regardless of timezone
+	// This addresses the issue with PreferSimpleProtocol in PostgreSQL
+
+	// Create a time in a timezone that's ahead of UTC
+	loc, err := time.LoadLocation("Europe/Berlin") // UTC+1 or UTC+2
+	if err != nil {
+		t.Skip("Could not load Europe/Berlin timezone")
+	}
+
+	// Create a time that would be the previous day in UTC
+	// For example: 2025-09-18 01:00:00 +02:00 is 2025-09-17 23:00:00 UTC
+	localTime := time.Date(2025, 9, 18, 1, 0, 0, 0, loc)
+	date := datatypes.Date(localTime)
+
+	// Get the Value() result
+	value, err := date.Value()
+	if err != nil {
+		t.Fatalf("date.Value() returned error: %v", err)
+	}
+
+	// The value should be a time.Time
+	timeValue, ok := value.(time.Time)
+	if !ok {
+		t.Fatalf("date.Value() should return time.Time, got %T", value)
+	}
+
+	// The date part should match the original date (2025-09-18)
+	// regardless of timezone, and should be in UTC
+	expectedYear, expectedMonth, expectedDay := 2025, time.September, 18
+	actualYear, actualMonth, actualDay := timeValue.Date()
+
+	if actualYear != expectedYear || actualMonth != expectedMonth || actualDay != expectedDay {
+		t.Errorf("Expected date %d-%02d-%02d, got %d-%02d-%02d",
+			expectedYear, expectedMonth, expectedDay,
+			actualYear, actualMonth, actualDay)
+	}
+
+	// The time should be in UTC
+	if timeValue.Location() != time.UTC {
+		t.Errorf("Expected UTC timezone, got %v", timeValue.Location())
+	}
+
+	// The time should be midnight (00:00:00)
+	hour, min, sec := timeValue.Clock()
+	if hour != 0 || min != 0 || sec != 0 {
+		t.Errorf("Expected midnight (00:00:00), got %02d:%02d:%02d", hour, min, sec)
+	}
+}
+
+func TestDateValueConsistency(t *testing.T) {
+	// Test that the same date in different timezones produces the same Value()
+	date := time.Date(2025, 9, 18, 15, 30, 45, 0, time.UTC)
+
+	// Create the same date in different timezones
+	utcDate := datatypes.Date(date)
+
+	loc, err := time.LoadLocation("America/New_York")
+	if err != nil {
+		t.Skip("Could not load America/New_York timezone")
+	}
+	nyDate := datatypes.Date(date.In(loc))
+
+	// Both should produce the same Value()
+	utcValue, err := utcDate.Value()
+	if err != nil {
+		t.Fatalf("utcDate.Value() returned error: %v", err)
+	}
+
+	nyValue, err := nyDate.Value()
+	if err != nil {
+		t.Fatalf("nyDate.Value() returned error: %v", err)
+	}
+
+	// Both values should be equal
+	if !utcValue.(time.Time).Equal(nyValue.(time.Time)) {
+		t.Errorf("Expected same value for same date in different timezones, got %v != %v", utcValue, nyValue)
+	}
+}