added NextResultSet implementation

Author: kmpm

sqlx.go

@@ -633,6 +633,16 @@ func (r *Rows) StructScan(dest interface{}) error {
 	return r.Err()
 }
 
+// NextResultSet moves to the next resultset if available and resets the field cache.
+func (r *Rows) NextResultSet() bool {
+	if !r.Rows.NextResultSet() {
+		return false
+	}
+	// reset fields cache
+	r.started = false
+	return true
+}
+
 // Connect to a database and verify with a ping.
 func Connect(driverName, dataSourceName string) (*DB, error) {
 	db, err := Open(driverName, dataSourceName)

sqlx_test.go

@@ -1892,3 +1892,110 @@ func TestIn130Regression(t *testing.T) {
 		}
 	})
 }
+
+func TestMultiResultSet(t *testing.T) {
+	RunWithSchema(defaultSchema, t, func(db *DB, t *testing.T, now string) {
+		var sp, sql string
+
+		loadDefaultFixture(db, t)
+
+		switch db.DriverName() {
+		case "mysql":
+			sp = `
+				CREATE PROCEDURE multiQuery()
+				BEGIN
+					SELECT first_name, last_name, email FROM person LIMIT 1;
+					SELECT country, telcode FROM place LIMIT 1;
+				END
+			`
+			sql = "CALL multiQuery();"
+		case "postgres":
+			sql = `
+				SELECT first_name, last_name, email FROM person LIMIT 1;
+				SELECT country, telcode FROM place LIMIT 1;
+			`
+		default:
+			// sqlite3 and postgres do not support multiple result sets with different row layout.
+			return
+		}
+
+		type Person struct {
+			FirstName string `db:"first_name"`
+			LastName  string `db:"last_name"`
+			Email     string `db:"email"`
+		}
+		type Place struct {
+			Country string `db:"country"`
+			TelCode string `db:"telcode"`
+		}
+
+		if sp != "" {
+			if _, err := db.Exec("DROP PROCEDURE IF EXISTS multiQuery"); err != nil {
+				t.Fatal(err)
+			}
+
+			if _, err := db.Exec(sp); err != nil {
+				t.Fatal(err)
+			}
+		}
+
+		rows, err := db.Queryx(sql)
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer rows.Close()
+
+		var (
+			person Person
+			place  Place
+		)
+
+		var i int
+		for rows.Next() {
+			i++
+			if err = rows.StructScan(&person); err != nil {
+				t.Fatal(err)
+			}
+		}
+		if i < 1 {
+			t.Errorf("[%s] Expected at least one record, got none", db.DriverName())
+		}
+
+		if !rows.NextResultSet() {
+			t.Fatalf("[%s] Expected a second recordset, got one", db.DriverName())
+		}
+
+		i = 0
+		for rows.Next() {
+			i++
+			if err = rows.StructScan(&place); err != nil {
+				t.Fatal(err)
+			}
+		}
+		if i < 1 {
+			t.Errorf("Expected at least one records, got none")
+		}
+
+		// nest no next
+		rows2, err := db.Queryx("SELECT first_name, last_name, email FROM person LIMIT 2;")
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer rows2.Close()
+
+		i = 0
+		for rows2.Next() {
+			i++
+			if err = rows2.StructScan(&person); err != nil {
+				t.Fatal(err)
+			}
+		}
+		if i < 2 {
+			t.Errorf("[%s] Expected at least 2 records, got %d", db.DriverName(), i)
+		}
+		if rows.NextResultSet() {
+			t.Fatalf("[%s] Did not expected a second recordset", db.DriverName())
+		}
+
+	})
+}