feat(training): add helper methods to TrainingID type

- String()
- MarshalJSON()
- UnmarshalJSON()

pkg/training/model.go

@@ -1,6 +1,10 @@
 package training
 
-import "github.com/google/uuid"
+import (
+	"encoding/json"
+
+	"github.com/google/uuid"
+)
 
 type TrainingID uuid.UUID
 
@@ -8,6 +12,23 @@ func NewTrainingID() TrainingID {
 	return TrainingID(uuid.Must(uuid.NewV7()))
 }
 
+func (id TrainingID) String() string {
+	return uuid.UUID(id).String()
+}
+
+func (id TrainingID) MarshalJSON() ([]byte, error) {
+	return json.Marshal(uuid.UUID(id))
+}
+
+func (id *TrainingID) UnmarshalJSON(data []byte) error {
+	var u uuid.UUID
+	if err := json.Unmarshal(data, &u); err != nil {
+		return err
+	}
+	*id = TrainingID(u)
+	return nil
+}
+
 type Training struct {
 	ID   TrainingID
 	Name string