remove ctx, db stuff and use callbacks instead

select.go

@@ -11,8 +11,11 @@ import (
 
 // https://www.sqlite.org/lang_select.html
 type SelectQuery struct {
-	Ctx context.Context
-	DB  *sql.DB
+	ctx context.Context
+	db  *sql.DB
+
+	queryFunc    func(Query) (*sql.Rows, error)
+	queryRowFunc func(Query) *sql.Row
 
 	distinct bool
 
@@ -48,6 +51,16 @@ func (q *SelectQuery) Columns(defs ...string) *SelectQuery {
 	return q
 }
 
+func (q *SelectQuery) Ctx(ctx context.Context) *SelectQuery {
+	q.ctx = ctx
+	return q
+}
+
+func (q *SelectQuery) DB(db *sql.DB) *SelectQuery {
+	q.db = db
+	return q
+}
+
 func (q *SelectQuery) Distinct(distinct bool) *SelectQuery {
 	q.distinct = distinct
 
@@ -114,15 +127,16 @@ func (q *SelectQuery) OrderBy(defs ...string) *SelectQuery {
 }
 
 func (q *SelectQuery) Query() (*sql.Rows, error) {
-	if q.DB != nil {
-		if q.Ctx != nil {
-			return q.DB.QueryContext(q.Ctx, q.String(), q.Args()...)
-		}
-
-		return q.DB.Query(q.String(), q.Args()...)
+	if q.queryFunc != nil {
+		return q.queryFunc(q)
 	}
 
-	return nil, ErrNoDatabase
+	return nil, nil
+}
+
+func (q *SelectQuery) QueryFunc(f func(Query) (*sql.Rows, error)) *SelectQuery {
+	q.queryFunc = f
+	return q
 }
 
 func (q *SelectQuery) QueryRecord() (record.Record, error) {
@@ -144,17 +158,18 @@ func (q *SelectQuery) QueryRecords() ([]record.Record, error) {
 }
 
 func (q *SelectQuery) QueryRow() *sql.Row {
-	if q.DB != nil {
-		if q.Ctx != nil {
-			return q.DB.QueryRowContext(q.Ctx, q.String(), q.Args()...)
-		}
-
-		return q.DB.QueryRow(q.String(), q.Args()...)
+	if q.queryRowFunc != nil {
+		return q.queryRowFunc(q)
 	}
 
 	return nil
 }
 
+func (q *SelectQuery) QueryRowFunc(f func(Query) *sql.Row) *SelectQuery {
+	q.queryRowFunc = f
+	return q
+}
+
 func (q *SelectQuery) String() string {
 	strs := []string{"select"}