Add TxOptions support to stdlib

stdlib/sql.go

@@ -170,16 +170,34 @@ func (c *Conn) Close() error {
 }
 
 func (c *Conn) Begin() (driver.Tx, error) {
+	return c.BeginTx(context.Background(), driver.TxOptions{})
+}
+
+func (c *Conn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, error) {
 	if !c.conn.IsAlive() {
 		return nil, driver.ErrBadConn
 	}
 
-	_, err := c.conn.Exec("begin")
-	if err != nil {
-		return nil, err
+	var pgxOpts pgx.TxOptions
+	switch sql.IsolationLevel(opts.Isolation) {
+	case sql.LevelDefault:
+	case sql.LevelReadUncommitted:
+		pgxOpts.IsoLevel = pgx.ReadUncommitted
+	case sql.LevelReadCommitted:
+		pgxOpts.IsoLevel = pgx.ReadCommitted
+	case sql.LevelSnapshot:
+		pgxOpts.IsoLevel = pgx.RepeatableRead
+	case sql.LevelSerializable:
+		pgxOpts.IsoLevel = pgx.Serializable
+	default:
+		return nil, fmt.Errorf("unsupported isolation: %v", opts.Isolation)
 	}
 
-	return &Tx{conn: c.conn}, nil
+	if opts.ReadOnly {
+		pgxOpts.AccessMode = pgx.ReadOnly
+	}
+
+	return c.conn.BeginEx(&pgxOpts)
 }
 
 func (c *Conn) Exec(query string, argsV []driver.Value) (driver.Result, error) {
@@ -389,17 +407,3 @@ func namedValueToInterface(argsV []driver.NamedValue) []interface{} {
 	}
 	return args
 }
-
-type Tx struct {
-	conn *pgx.Conn
-}
-
-func (t *Tx) Commit() error {
-	_, err := t.conn.Exec("commit")
-	return err
-}
-
-func (t *Tx) Rollback() error {
-	_, err := t.conn.Exec("rollback")
-	return err
-}

stdlib/sql_test.go

@@ -2,6 +2,7 @@ package stdlib_test
 
 import (
 	"bytes"
+	"context"
 	"database/sql"
 	"testing"
 
@@ -603,3 +604,84 @@ func TestTransactionLifeCycle(t *testing.T) {
 
 	ensureConnValid(t, db)
 }
+
+func TestConnBeginTxIsolation(t *testing.T) {
+	db := openDB(t)
+	defer closeDB(t, db)
+
+	var defaultIsoLevel string
+	err := db.QueryRow("show transaction_isolation").Scan(&defaultIsoLevel)
+	if err != nil {
+		t.Fatalf("QueryRow failed: %v", err)
+	}
+
+	supportedTests := []struct {
+		sqlIso sql.IsolationLevel
+		pgIso  string
+	}{
+		{sqlIso: sql.LevelDefault, pgIso: defaultIsoLevel},
+		{sqlIso: sql.LevelReadUncommitted, pgIso: "read uncommitted"},
+		{sqlIso: sql.LevelReadCommitted, pgIso: "read committed"},
+		{sqlIso: sql.LevelSnapshot, pgIso: "repeatable read"},
+		{sqlIso: sql.LevelSerializable, pgIso: "serializable"},
+	}
+	for i, tt := range supportedTests {
+		func() {
+			tx, err := db.BeginTx(context.Background(), &sql.TxOptions{Isolation: tt.sqlIso})
+			if err != nil {
+				t.Errorf("%d. BeginTx failed: %v", i, err)
+				return
+			}
+			defer tx.Rollback()
+
+			var pgIso string
+			err = tx.QueryRow("show transaction_isolation").Scan(&pgIso)
+			if err != nil {
+				t.Errorf("%d. QueryRow failed: %v", i, err)
+			}
+
+			if pgIso != tt.pgIso {
+				t.Errorf("%d. pgIso => %s, want %s", i, pgIso, tt.pgIso)
+			}
+		}()
+	}
+
+	unsupportedTests := []struct {
+		sqlIso sql.IsolationLevel
+	}{
+		{sqlIso: sql.LevelWriteCommitted},
+		{sqlIso: sql.LevelLinearizable},
+	}
+	for i, tt := range unsupportedTests {
+		tx, err := db.BeginTx(context.Background(), &sql.TxOptions{Isolation: tt.sqlIso})
+		if err == nil {
+			t.Errorf("%d. BeginTx should have failed", i)
+			tx.Rollback()
+		}
+	}
+
+	ensureConnValid(t, db)
+}
+
+func TestConnBeginTxReadOnly(t *testing.T) {
+	db := openDB(t)
+	defer closeDB(t, db)
+
+	tx, err := db.BeginTx(context.Background(), &sql.TxOptions{ReadOnly: true})
+	if err != nil {
+		t.Fatalf("BeginTx failed: %v", err)
+	}
+	defer tx.Rollback()
+
+	var pgReadOnly string
+	err = tx.QueryRow("show transaction_read_only").Scan(&pgReadOnly)
+	if err != nil {
+		t.Errorf("%d. QueryRow failed: %v", err)
+	}
+
+	if pgReadOnly != "on" {
+		t.Errorf("pgReadOnly => %s, want %s", pgReadOnly, "on")
+	}
+
+	ensureConnValid(t, db)
+}