diff options
Diffstat (limited to 'db.go')
| -rw-r--r-- | db.go | 52 |
1 files changed, 51 insertions, 1 deletions
@@ -6,6 +6,7 @@ package oblast import ( "context" "database/sql" + "fmt" "reflect" "sync" ) @@ -26,9 +27,58 @@ func NewDB(db *sql.DB, dialect Dialect) *DB { } } +// TODO: remove func Keks[T IsTable](ctx context.Context, db *DB) error { _, err := db.getPlan(reflect.TypeFor[T]()) return err } -// TODO: Begin() -> custom Tx type +// TODO: Begin() -> custom Tx type; add interface to allow Select() et all to take either *DB or *Tx + +func Select[T any](ctx context.Context, db *DB, query string, args ...any) ([]T, error) { + // TODO: minimize function body to avoid binary size blowup from monomorphization + // TODO: catch error from rows.Close(), if any + // TODO: add context to errors + + plan, err := db.getPlan(reflect.TypeFor[T]()) + if err != nil { + return nil, err + } + rows, err := db.Query(query, args...) + if err != nil { + return nil, err + } + defer rows.Close() + + columnNames, err := rows.Columns() + if err != nil { + return nil, err + } + indexes := make([][]int, len(columnNames)) + for idx, columnName := range columnNames { + var ok bool + indexes[idx], ok = plan.IndexByColumnName[columnName] + if !ok { + var zero T + return nil, fmt.Errorf("result has column %q in position %d, but no field in %T has `db:%[1]q`", + columnName, idx, zero) + } + } + + var result []T + slots := make([]any, len(indexes)) + for rows.Next() { + var target T + rvalue := reflect.ValueOf(&target).Elem() + for idx, index := range indexes { + slots[idx] = rvalue.FieldByIndex(index).Addr().Interface() + } + err := rows.Scan(slots...) + if err != nil { + return nil, err + } + result = append(result, target) + } + + return result, nil +} |