Add JSON wrapper type

types/json.go

@@ -0,0 +1,95 @@
+package types
+
+import (
+	"bytes"
+	"database/sql/driver"
+	"encoding"
+	"encoding/json"
+	"fmt"
+	"reflect"
+
+	"github.com/aarondl/opt"
+)
+
+//nolint:gochecknoglobals
+var (
+	encodingTextMarshalerIntf   = reflect.TypeOf((*encoding.TextMarshaler)(nil)).Elem()
+	encodingTextUnmarshalerIntf = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem()
+)
+
+type JSON[T any] struct {
+	value T
+}
+
+func (j JSON[T]) Get() T {
+	return j.value
+}
+
+// Value implements the driver Valuer interface.
+func (j JSON[T]) Value() (driver.Value, error) {
+	buf := &bytes.Buffer{}
+	err := json.NewEncoder(buf).Encode(j)
+	return buf.Bytes(), err
+}
+
+// Scan implements the Scanner interface.
+func (j *JSON[T]) Scan(value interface{}) error {
+	var err error
+
+	switch x := value.(type) {
+	case string:
+		err = json.NewDecoder(bytes.NewBuffer([]byte(x))).Decode(j)
+	case []byte:
+		err = json.NewDecoder(bytes.NewBuffer(x)).Decode(j)
+	case nil:
+		return nil
+
+	default:
+		err = fmt.Errorf("cannot scan type %T: %v", value, value)
+	}
+
+	return err
+}
+
+// UnmarshalJSON implements json.Unmarshaler.
+func (j *JSON[T]) UnmarshalJSON(data []byte) error {
+	return json.Unmarshal(data, &j.value)
+}
+
+// MarshalJSON implements json.Marshaler.
+func (j JSON[T]) MarshalJSON() ([]byte, error) {
+	return json.Marshal(j.value)
+}
+
+// MarshalText implements encoding.TextMarshaler.
+func (j JSON[T]) MarshalText() ([]byte, error) {
+	refVal := reflect.ValueOf(j.value)
+	if refVal.Type().Implements(encodingTextMarshalerIntf) {
+		valuer := refVal.Interface().(encoding.TextMarshaler)
+		return valuer.MarshalText()
+	}
+
+	var text string
+	if err := opt.ConvertAssign(&text, j.value); err != nil {
+		return nil, err
+	}
+	return []byte(text), nil
+}
+
+// UnmarshalText implements encoding.TextUnmarshaler.
+func (j *JSON[T]) UnmarshalText(text []byte) error {
+	refVal := reflect.ValueOf(&j.value)
+	if refVal.Type().Implements(encodingTextUnmarshalerIntf) {
+		valuer := refVal.Interface().(encoding.TextUnmarshaler)
+		if err := valuer.UnmarshalText(text); err != nil {
+			return err
+		}
+		return nil
+	}
+
+	if err := opt.ConvertAssign(&j.value, string(text)); err != nil {
+		return err
+	}
+
+	return nil
+}