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juanfont.headscale/hscontrol/db/text_serialiser.go
Kristoffer Dalby bc9e83b52e
use gorm serialiser instead of custom hooks (#2156)
* add sqlite to debug/test image

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

* test using gorm serialiser instead of custom hooks

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

---------

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>
2024-10-02 11:41:58 +02:00

100 lines
2.7 KiB
Go

package db
import (
"context"
"encoding"
"fmt"
"reflect"
"gorm.io/gorm/schema"
)
// Got from https://github.com/xdg-go/strum/blob/main/types.go
var textUnmarshalerType = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem()
func isTextUnmarshaler(rv reflect.Value) bool {
return rv.Type().Implements(textUnmarshalerType)
}
func maybeInstantiatePtr(rv reflect.Value) {
if rv.Kind() == reflect.Ptr && rv.IsNil() {
np := reflect.New(rv.Type().Elem())
rv.Set(np)
}
}
func decodingError(name string, err error) error {
return fmt.Errorf("error decoding to %s: %w", name, err)
}
// TextSerialiser implements the Serialiser interface for fields that
// have a type that implements encoding.TextUnmarshaler.
type TextSerialiser struct{}
func (TextSerialiser) Scan(ctx context.Context, field *schema.Field, dst reflect.Value, dbValue interface{}) (err error) {
fieldValue := reflect.New(field.FieldType)
// If the field is a pointer, we need to dereference it to get the actual type
// so we do not end with a second pointer.
if fieldValue.Elem().Kind() == reflect.Ptr {
fieldValue = fieldValue.Elem()
}
if dbValue != nil {
var bytes []byte
switch v := dbValue.(type) {
case []byte:
bytes = v
case string:
bytes = []byte(v)
default:
return fmt.Errorf("failed to unmarshal text value: %#v", dbValue)
}
if isTextUnmarshaler(fieldValue) {
maybeInstantiatePtr(fieldValue)
f := fieldValue.MethodByName("UnmarshalText")
args := []reflect.Value{reflect.ValueOf(bytes)}
ret := f.Call(args)
if !ret[0].IsNil() {
return decodingError(field.Name, ret[0].Interface().(error))
}
// If the underlying field is to a pointer type, we need to
// assign the value as a pointer to it.
// If it is not a pointer, we need to assign the value to the
// field.
dstField := field.ReflectValueOf(ctx, dst)
if dstField.Kind() == reflect.Ptr {
dstField.Set(fieldValue)
} else {
dstField.Set(fieldValue.Elem())
}
return nil
} else {
return fmt.Errorf("unsupported type: %T", fieldValue.Interface())
}
}
return
}
func (TextSerialiser) Value(ctx context.Context, field *schema.Field, dst reflect.Value, fieldValue interface{}) (interface{}, error) {
switch v := fieldValue.(type) {
case encoding.TextMarshaler:
// If the value is nil, we return nil, however, go nil values are not
// always comparable, particularly when reflection is involved:
// https://dev.to/arxeiss/in-go-nil-is-not-equal-to-nil-sometimes-jn8
if v == nil || (reflect.ValueOf(v).Kind() == reflect.Ptr && reflect.ValueOf(v).IsNil()) {
return nil, nil
}
b, err := v.MarshalText()
if err != nil {
return nil, err
}
return string(b), nil
default:
return nil, fmt.Errorf("only encoding.TextMarshaler is supported, got %t", v)
}
}