[Bug] Statement Query and Exec methods can not be used with sql.Conn

internal/jet/statement.go

@@ -11,23 +11,23 @@ import (
 type Statement interface {
 	// Sql returns parametrized sql query with list of arguments.
 	Sql() (query string, args []interface{})
-	// DebugSql returns debug query where every parametrized placeholder is replaced with its argument.
+	// DebugSql returns debug query where every parametrized placeholder is replaced with its argument string representation.
 	// Do not use it in production. Use it only for debug purposes.
 	DebugSql() (query string)
-	// Query executes statement over database connection/transaction db and stores row result in destination.
+	// Query executes statement over database connection/transaction db and stores row results in destination.
 	// Destination can be either pointer to struct or pointer to a slice.
 	// If destination is pointer to struct and query result set is empty, method returns qrm.ErrNoRows.
-	Query(db qrm.DB, destination interface{}) error
+	Query(db qrm.Queryable, destination interface{}) error
 	// QueryContext executes statement with a context over database connection/transaction db and stores row result in destination.
 	// Destination can be either pointer to struct or pointer to a slice.
 	// If destination is pointer to struct and query result set is empty, method returns qrm.ErrNoRows.
-	QueryContext(ctx context.Context, db qrm.DB, destination interface{}) error
+	QueryContext(ctx context.Context, db qrm.Queryable, destination interface{}) error
 	// Exec executes statement over db connection/transaction without returning any rows.
-	Exec(db qrm.DB) (sql.Result, error)
+	Exec(db qrm.Executable) (sql.Result, error)
 	// ExecContext executes statement with context over db connection/transaction without returning any rows.
-	ExecContext(ctx context.Context, db qrm.DB) (sql.Result, error)
+	ExecContext(ctx context.Context, db qrm.Executable) (sql.Result, error)
 	// Rows executes statements over db connection/transaction and returns rows
-	Rows(ctx context.Context, db qrm.DB) (*Rows, error)
+	Rows(ctx context.Context, db qrm.Queryable) (*Rows, error)
 }
 
 // Rows wraps sql.Rows type to add query result mapping for Scan method
@@ -86,11 +86,11 @@ func (s *serializerStatementInterfaceImpl) DebugSql() (query string) {
 	return
 }
 
-func (s *serializerStatementInterfaceImpl) Query(db qrm.DB, destination interface{}) error {
+func (s *serializerStatementInterfaceImpl) Query(db qrm.Queryable, destination interface{}) error {
 	return s.QueryContext(context.Background(), db, destination)
 }
 
-func (s *serializerStatementInterfaceImpl) QueryContext(ctx context.Context, db qrm.DB, destination interface{}) error {
+func (s *serializerStatementInterfaceImpl) QueryContext(ctx context.Context, db qrm.Queryable, destination interface{}) error {
 	query, args := s.Sql()
 
 	callLogger(ctx, s)
@@ -112,11 +112,11 @@ func (s *serializerStatementInterfaceImpl) QueryContext(ctx context.Context, db
 	return err
 }
 
-func (s *serializerStatementInterfaceImpl) Exec(db qrm.DB) (res sql.Result, err error) {
+func (s *serializerStatementInterfaceImpl) Exec(db qrm.Executable) (res sql.Result, err error) {
 	return s.ExecContext(context.Background(), db)
 }
 
-func (s *serializerStatementInterfaceImpl) ExecContext(ctx context.Context, db qrm.DB) (res sql.Result, err error) {
+func (s *serializerStatementInterfaceImpl) ExecContext(ctx context.Context, db qrm.Executable) (res sql.Result, err error) {
 	query, args := s.Sql()
 
 	callLogger(ctx, s)
@@ -141,7 +141,7 @@ func (s *serializerStatementInterfaceImpl) ExecContext(ctx context.Context, db q
 	return res, err
 }
 
-func (s *serializerStatementInterfaceImpl) Rows(ctx context.Context, db qrm.DB) (*Rows, error) {
+func (s *serializerStatementInterfaceImpl) Rows(ctx context.Context, db qrm.Queryable) (*Rows, error) {
 	query, args := s.Sql()
 
 	callLogger(ctx, s)

qrm/db.go

@@ -13,3 +13,13 @@ type DB interface {
 	Query(query string, args ...interface{}) (*sql.Rows, error)
 	QueryContext(ctx context.Context, query string, args ...interface{}) (*sql.Rows, error)
 }
+
+// Queryable interface for sql QueryContext method
+type Queryable interface {
+	QueryContext(ctx context.Context, query string, args ...interface{}) (*sql.Rows, error)
+}
+
+// Executable interface for sql ExecContext method
+type Executable interface {
+	ExecContext(ctx context.Context, query string, args ...interface{}) (sql.Result, error)
+}

qrm/qrm.go

@@ -17,7 +17,7 @@ var ErrNoRows = errors.New("qrm: no rows in result set")
 // using context `ctx` into destination `destPtr`.
 // Destination can be either pointer to struct or pointer to slice of structs.
 // If destination is pointer to struct and query result set is empty, method returns qrm.ErrNoRows.
-func Query(ctx context.Context, db DB, query string, args []interface{}, destPtr interface{}) (rowsProcessed int64, err error) {
+func Query(ctx context.Context, db Queryable, query string, args []interface{}, destPtr interface{}) (rowsProcessed int64, err error) {
 
 	utils.MustBeInitializedPtr(db, "jet: db is nil")
 	utils.MustBeInitializedPtr(destPtr, "jet: destination is nil")
@@ -88,7 +88,7 @@ func ScanOneRowToDest(scanContext *ScanContext, rows *sql.Rows, destPtr interfac
 	return nil
 }
 
-func queryToSlice(ctx context.Context, db DB, query string, args []interface{}, slicePtr interface{}) (rowsProcessed int64, err error) {
+func queryToSlice(ctx context.Context, db Queryable, query string, args []interface{}, slicePtr interface{}) (rowsProcessed int64, err error) {
 	if ctx == nil {
 		ctx = context.Background()
 	}

tests/postgres/select_test.go

@@ -1,6 +1,8 @@
 package postgres
 
 import (
+	"context"
+	"github.com/go-jet/jet/v2/qrm"
 	"testing"
 	"time"
 
@@ -24,9 +26,9 @@ FROM dvds.actor
 WHERE actor.actor_id = 2;
 `
 
-	query := Actor.
-		SELECT(Actor.AllColumns).
+	query := SELECT(Actor.AllColumns).
 		DISTINCT().
+		FROM(Actor).
 		WHERE(Actor.ActorID.EQ(Int(2)))
 
 	testutils.AssertDebugStatementSql(t, query, expectedSQL, int64(2))
@@ -44,7 +46,6 @@ WHERE actor.actor_id = 2;
 	}
 
 	testutils.AssertDeepEqual(t, actor, expectedActor)
-
 	requireLogged(t, query)
 }
 
@@ -166,7 +167,7 @@ SELECT customer.customer_id AS "customer.customer_id",
 FROM dvds.customer
 ORDER BY customer.customer_id ASC;
 `
-	customers := []model.Customer{}
+	var customers []model.Customer
 
 	query := Customer.SELECT(Customer.AllColumns).ORDER_BY(Customer.CustomerID.ASC())
 
@@ -2680,6 +2681,48 @@ SELECT dvds.get_film_count(100, 120) AS "film_count";
 	require.Equal(t, dest.FilmCount, 165)
 }
 
+func TestScanUsingConn(t *testing.T) {
+	conn, err := db.Conn(context.Background())
+	require.NoError(t, err)
+	defer conn.Close()
+
+	stmt := SELECT(Actor.AllColumns).
+		FROM(Actor).
+		DISTINCT().
+		WHERE(Actor.ActorID.EQ(Int(2)))
+
+	var actor model.Actor
+	err = stmt.Query(conn, &actor)
+	require.NoError(t, err)
+	err = stmt.QueryContext(context.Background(), conn, &actor)
+	require.NoError(t, err)
+	testutils.AssertDeepEqual(t, actor, model.Actor{
+		ActorID:    2,
+		FirstName:  "Nick",
+		LastName:   "Wahlberg",
+		LastUpdate: *testutils.TimestampWithoutTimeZone("2013-05-26 14:47:57.62", 2),
+	})
+
+	_, err = stmt.Exec(conn)
+	require.NoError(t, err)
+	_, err = stmt.ExecContext(context.Background(), conn)
+	require.NoError(t, err)
+
+	t.Run("ensure qrm.DB still works", func(t *testing.T) {
+		var qrmDB qrm.DB = db
+
+		err = stmt.Query(qrmDB, &actor)
+		require.NoError(t, err)
+		err = stmt.QueryContext(context.Background(), qrmDB, &actor)
+		require.NoError(t, err)
+
+		_, err = stmt.Exec(qrmDB)
+		require.NoError(t, err)
+		_, err = stmt.ExecContext(context.Background(), qrmDB)
+		require.NoError(t, err)
+	})
+}
+
 var customer0 = model.Customer{
 	CustomerID: 1,
 	StoreID:    1,