Function Load

load.go:31–126

Load loads any value from sql.Rows. value can be: 1. simple type like int64, string, etc. 2. sql.Scanner, which allows loading with custom types. 3. map; the first column from SQL result loaded to the key, and the rest of columns will be loaded into the value. This is useful to dedup SQL result

(rows *sql.Rows, value interface{})

// 4. map of slice; like map, values with the same key are
// collected with a slice.
func Load(rows *sql.Rows, value interface{}) (int, error) {
	defer rows.Close()

	column, err := rows.Columns()
	if err != nil {
		return 0, err
	}
	ptr := make([]interface{}, len(column))

	var v reflect.Value
	var elemType reflect.Type

	if il, ok := value.(interfaceLoader); ok {
		v = reflect.ValueOf(il.v)
		elemType = il.typ
	} else {
		v = reflect.ValueOf(value)
	}

	if v.Kind() != reflect.Ptr || v.IsNil() {
		return 0, ErrInvalidPointer
	}
	v = v.Elem()
	isScanner := v.Addr().Type().Implements(typeScanner)
	isSlice := v.Kind() == reflect.Slice && v.Type().Elem().Kind() != reflect.Uint8 && !isScanner
	isMap := v.Kind() == reflect.Map && !isScanner
	isMapOfSlices := isMap && v.Type().Elem().Kind() == reflect.Slice && v.Type().Elem().Elem().Kind() != reflect.Uint8
	if isMap {
		v.Set(reflect.MakeMap(v.Type()))
	}

	s := newTagStore()
	count := 0
	for rows.Next() {
		var elem, keyElem reflect.Value

		if elemType != nil {
			elem = reflectAlloc(elemType)
		} else if isMapOfSlices {
			elem = reflectAlloc(v.Type().Elem().Elem())
		} else if isSlice || isMap {
			elem = reflectAlloc(v.Type().Elem())
		} else {
			elem = v
		}

		if isMap {
			err := s.findPtr(elem, column[1:], ptr[1:])
			if err != nil {
				return 0, err
			}
			keyElem = reflectAlloc(v.Type().Key())
			err = s.findPtr(keyElem, column[:1], ptr[:1])
			if err != nil {
				return 0, err
			}
		} else {
			err := s.findPtr(elem, column, ptr)