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1 year ago
package sqlx
import (
"errors"
"git.diulo.com/mogfee/kit/mapping"
"reflect"
"strings"
)
const tagName = "db"
var (
ErrNotMatchDestination = errors.New("not matching destination to scan")
ErrNotReadableValue = errors.New("value not addressable or interfaceable")
ErrNotSettable = errors.New("passed in variable is not settable")
ErrUnsupportedValueType = errors.New("unsupported unmarshal type")
)
type rowsScanner interface {
Columns() ([]string, error)
Err() error
Next() bool
Scan(v ...any) error
}
func unmarshalRow(v any, scanner rowsScanner, strict bool) error {
if !scanner.Next() {
if err := scanner.Err(); err != nil {
return err
}
return ErrNotFound
}
rv := reflect.ValueOf(v)
if err := mapping.ValidatePtr(&rv); err != nil {
return err
}
rte := reflect.TypeOf(v).Elem()
rve := rv.Elem()
switch rte.Kind() {
case reflect.Bool,
reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
reflect.Float32, reflect.Float64,
reflect.String:
if rve.CanSet() {
return scanner.Scan(v)
}
return ErrNotSettable
case reflect.Struct:
columns, err := scanner.Columns()
if err != nil {
return err
}
values, err := mapStructFieldsIntoSlice(rve, columns, strict)
if err != nil {
return err
}
return scanner.Scan(values...)
default:
return ErrUnsupportedValueType
}
}
func unmarshalRows(v any, scanner rowsScanner, strict bool) error {
rv := reflect.ValueOf(v)
if err := mapping.ValidatePtr(&rv); err != nil {
return err
}
rt := reflect.TypeOf(v)
rte := rt.Elem()
rve := rv.Elem()
switch rte.Kind() {
case reflect.Slice:
if rve.CanSet() {
ptr := rte.Elem().Kind() == reflect.Ptr
appendFn := func(item reflect.Value) {
if ptr {
rve.Set(reflect.Append(rve, item))
} else {
rve.Set(reflect.Append(rve, reflect.Indirect(item)))
}
}
fillFn := func(value any) error {
if rve.CanSet() {
if err := scanner.Scan(value); err != nil {
return err
}
appendFn(reflect.ValueOf(value))
return nil
}
return ErrNotSettable
}
base := mapping.Deref(rte.Elem())
switch base.Kind() {
case reflect.Bool,
reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
reflect.Float32, reflect.Float64,
reflect.String:
for scanner.Next() {
value := reflect.New(base)
if err := fillFn(value.Interface()); err != nil {
return err
}
}
case reflect.Struct:
columns, err := scanner.Columns()
if err != nil {
return err
}
for scanner.Next() {
value := reflect.New(base)
values, err := mapStructFieldsIntoSlice(value, columns, strict)
if err != nil {
return err
}
if err = scanner.Scan(values...); err != nil {
return err
}
appendFn(value)
}
default:
return ErrUnsupportedValueType
}
return nil
}
return ErrNotSettable
default:
return ErrUnsupportedValueType
}
}
func mapStructFieldsIntoSlice(v reflect.Value, columns []string, strict bool) ([]any, error) {
fields := unwrapFields(v)
if strict && len(columns) < len(fields) {
return nil, ErrNotMatchDestination
}
taggedMap, err := getTaggedFieldValueMap(v)
if err != nil {
return nil, err
}
values := make([]any, len(columns))
if len(taggedMap) == 0 {
for i := 0; i < len(values); i++ {
valueField := fields[i]
switch valueField.Kind() {
case reflect.Ptr:
if !valueField.CanInterface() {
return nil, ErrNotReadableValue
}
if valueField.IsNil() {
baseValueType := mapping.Deref(valueField.Type())
valueField.Set(reflect.New(baseValueType))
}
values[i] = valueField.Interface()
default:
if !valueField.CanAddr() || !valueField.Addr().CanInterface() {
return nil, ErrNotReadableValue
}
values[i] = valueField.Addr().Interface()
}
}
} else {
for i, column := range columns {
if tagged, ok := taggedMap[column]; ok {
values[i] = tagged
} else {
var anoymouse any
values[i] = &anoymouse
}
}
}
return values, nil
}
func getTaggedFieldValueMap(v reflect.Value) (map[string]any, error) {
rt := mapping.Deref(v.Type())
size := rt.NumField()
result := make(map[string]any, size)
for i := 0; i < size; i++ {
key := parseTagName(rt.Field(i))
if len(key) == 0 {
return nil, nil
}
valueField := reflect.Indirect(v).Field(i)
switch valueField.Kind() {
case reflect.Ptr:
if !valueField.CanInterface() {
return nil, ErrNotReadableValue
}
if valueField.IsNil() {
baseValueType := mapping.Deref(valueField.Type())
valueField.Set(reflect.New(baseValueType))
}
result[key] = valueField.Interface()
default:
if !valueField.CanAddr() || !valueField.Addr().CanInterface() {
return nil, ErrNotReadableValue
}
result[key] = valueField.Addr().Interface()
}
}
return result, nil
}
func parseTagName(field reflect.StructField) string {
key := field.Tag.Get(tagName)
if len(key) == 0 {
return ""
}
options := strings.Split(key, ",")
return options[0]
}
func unwrapFields(v reflect.Value) []reflect.Value {
var fields []reflect.Value
indirect := reflect.Indirect(v)
for i := 0; i < indirect.NumField(); i++ {
child := indirect.Field(i)
if child.Kind() == reflect.Ptr && child.IsNil() {
baseValueType := mapping.Deref(child.Type())
child.Set(reflect.New(baseValueType))
}
child = reflect.Indirect(child)
childType := indirect.Type().Field(i)
if child.Kind() == reflect.Struct && childType.Anonymous {
fields = append(fields, unwrapFields(child)...)
} else {
fields = append(fields, child)
}
}
return fields
}