PostgreSQL does not return expected timezone

db.go

@@ -47,13 +47,13 @@ func OpenTestConnection() (db *gorm.DB, err error) {
 	case "mysql":
 		log.Println("testing mysql...")
 		if dbDSN == "" {
-			dbDSN = "gorm:gorm@tcp(localhost:9910)/gorm?charset=utf8&parseTime=True&loc=Local"
+			dbDSN = "gorm:gorm@tcp(localhost:9910)/gorm?charset=utf8&parseTime=True&loc=UTC"
 		}
 		db, err = gorm.Open(mysql.Open(dbDSN), &gorm.Config{})
 	case "postgres":
 		log.Println("testing postgres...")
 		if dbDSN == "" {
-			dbDSN = "user=gorm password=gorm host=localhost dbname=gorm port=9920 sslmode=disable TimeZone=Asia/Shanghai"
+			dbDSN = "user=gorm password=gorm host=localhost dbname=gorm port=9920 sslmode=disable TimeZone=UTC"
 		}
 		db, err = gorm.Open(postgres.Open(dbDSN), &gorm.Config{})
 	case "sqlserver":

docker-compose.yml

@@ -15,7 +15,7 @@ services:
     ports:
       - 9920:5432
     environment:
-      - TZ=Asia/Shanghai
+      - TZ=UTC
       - POSTGRES_DB=gorm
       - POSTGRES_USER=gorm
       - POSTGRES_PASSWORD=gorm

go.mod

@@ -1,39 +1,44 @@
 module gorm.io/playground
 
-go 1.22.0
+go 1.23.0
 
 toolchain go1.23.3
 
 require (
+	github.com/jackc/pgx/v5 v5.7.2
+	github.com/stretchr/testify v1.10.0
 	gorm.io/driver/mysql v1.5.7
-	gorm.io/driver/postgres v1.5.10
-	gorm.io/driver/sqlite v1.5.6
+	gorm.io/driver/postgres v1.5.11
+	gorm.io/driver/sqlite v1.5.7
 	gorm.io/driver/sqlserver v1.5.4
 	gorm.io/gen v0.3.26
 	gorm.io/gorm v1.25.12
 )
 
 require (
 	filippo.io/edwards25519 v1.1.0 // indirect
-	github.com/go-sql-driver/mysql v1.8.1 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/go-sql-driver/mysql v1.9.0 // indirect
 	github.com/golang-sql/civil v0.0.0-20220223132316-b832511892a9 // indirect
 	github.com/golang-sql/sqlexp v0.1.0 // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/jackc/pgpassfile v1.0.0 // indirect
 	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
-	github.com/jackc/pgx/v5 v5.7.1 // indirect
 	github.com/jackc/puddle/v2 v2.2.2 // indirect
 	github.com/jinzhu/inflection v1.0.0 // indirect
 	github.com/jinzhu/now v1.1.5 // indirect
+	github.com/kr/text v0.2.0 // indirect
 	github.com/mattn/go-sqlite3 v1.14.24 // indirect
-	github.com/microsoft/go-mssqldb v1.7.2 // indirect
-	golang.org/x/crypto v0.29.0 // indirect
-	golang.org/x/mod v0.22.0 // indirect
-	golang.org/x/sync v0.9.0 // indirect
-	golang.org/x/sys v0.27.0 // indirect
-	golang.org/x/text v0.20.0 // indirect
-	golang.org/x/tools v0.27.0 // indirect
-	gorm.io/datatypes v1.2.4 // indirect
+	github.com/microsoft/go-mssqldb v1.8.0 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/rogpeppe/go-internal v1.14.1 // indirect
+	golang.org/x/crypto v0.35.0 // indirect
+	golang.org/x/mod v0.23.0 // indirect
+	golang.org/x/sync v0.11.0 // indirect
+	golang.org/x/text v0.22.0 // indirect
+	golang.org/x/tools v0.30.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+	gorm.io/datatypes v1.2.5 // indirect
 	gorm.io/hints v1.1.2 // indirect
 	gorm.io/plugin/dbresolver v1.5.3 // indirect
 )

main_test.go

@@ -2,6 +2,18 @@ package main
 
 import (
 	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"gorm.io/driver/postgres"
+	"gorm.io/gorm"
+
+	"context"
+
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgtype"
+	"github.com/jackc/pgx/v5/pgxpool"
+	"github.com/jackc/pgx/v5/stdlib"
 )
 
 // GORM_REPO: https://github.com/go-gorm/gorm.git
@@ -18,3 +30,91 @@ func TestGORM(t *testing.T) {
 		t.Errorf("Failed, got error: %v", err)
 	}
 }
+
+func TestTimeZone(t *testing.T) {
+	birthday := time.Date(2023, 11, 12, 9, 7, 18, 0, time.UTC)
+	user := User{Name: "TimeZone UTC", Birthday: &birthday}
+
+	if err := DB.Create(&user).Error; err != nil {
+		t.Errorf("Failed, got error: %v", err)
+		t.FailNow()
+	}
+
+	birthdayResult := *user.Birthday
+	assert.Equal(t, birthday, birthdayResult)
+
+	userResult := User{}
+
+	if err := DB.Where("name = ?", "TimeZone UTC").First(&userResult).Error; err != nil {
+		t.Errorf("Failed, got error: %v", err)
+		t.FailNow()
+	}
+
+	birthdayResult = *userResult.Birthday
+	assert.Equal(t, birthday, birthdayResult)
+
+}
+
+func TestPGXPooltoSqlDB(t *testing.T) {
+	if DB.Dialector.Name() != "postgres" {
+		t.Skip("test only runs in postgres")
+	}
+
+	// The following test shows how to open a pgxpool with the forced return of timezone as UTC.
+	ctx := context.Background()
+
+	uri := "user=gorm password=gorm host=localhost dbname=gorm port=9920 sslmode=disable TimeZone=UTC"
+
+	config, err := pgxpool.ParseConfig(uri)
+	if err != nil {
+		t.Errorf("Failed, got error: %v", err)
+		t.FailNow()
+	}
+
+	config.AfterConnect = func(ctx context.Context, conn *pgx.Conn) error {
+		conn.TypeMap().RegisterType(&pgtype.Type{
+			Name:  "timestamptz",
+			OID:   pgtype.TimestamptzOID,
+			Codec: &pgtype.TimestamptzCodec{ScanLocation: time.UTC}, // It would be better to parse the connection string for TimeZone and use that here.  Or have some other way of specifying it.
+		})
+
+		return nil
+	}
+
+	pool, err := pgxpool.NewWithConfig(ctx, config)
+	if err != nil {
+		t.Errorf("Failed, got error: %v", err)
+		t.FailNow()
+	}
+
+	// test connection to ensure all is well
+	if err = pool.Ping(ctx); err != nil {
+		pool.Close()
+		t.Errorf("Failed, got error: %v", err)
+		t.FailNow()
+	}
+
+	nativeDB := stdlib.OpenDBFromPool(pool)
+	db, err := gorm.Open(postgres.New(postgres.Config{Conn: nativeDB}))
+	if err != nil {
+		t.Errorf("Failed, got error: %v", err)
+		t.FailNow()
+	}
+
+	birthday := time.Date(2023, 11, 12, 9, 7, 18, 0, time.UTC)
+	userResult := User{}
+
+	if err := db.Where("name = ?", "TimeZone UTC").First(&userResult).Error; err != nil {
+		t.Errorf("Failed, got error: %v", err)
+		t.FailNow()
+	}
+
+	birthdayResult := *userResult.Birthday
+	assert.Equal(t, birthday, birthdayResult)
+
+	// Need some way to allow the closing of the connection pool after the gorm connection has closed.
+	if sqlDB, _ := db.DB(); sqlDB != nil {
+		sqlDB.Close()
+		pool.Close()
+	}
+}