implement recursive deletion for gridfs files when Delete() is called on a document

document_internals.go

@@ -180,6 +180,7 @@ func doDelete(d *Document, arg interface{}) error {
 	_, err := c.DeleteOne(context.TODO(), bson.M{"_id": self.Id()})
 	if err == nil {
 		d.exists = false
+		err = gridFsDel(arg, *d.model)
 	}
 	return err
 }

gridfs.go

@@ -105,6 +105,82 @@ func gridFsLoad(val any, g gridFSReference, field string) any {
 	return doc.Interface()
 }
 
+func gridFsDel(val any, imodel Model) error {
+	var rerr error
+	v := reflect.ValueOf(val)
+	el := v
+	if v.Kind() == reflect.Pointer {
+		el = el.Elem()
+	}
+	switch el.Kind() {
+	case reflect.Struct:
+		for i := 0; i < el.NumField(); i++ {
+			ft := el.Type().Field(i)
+			fv := el.Field(i)
+			if !ft.IsExported() {
+				continue
+			}
+			_, err := structtag.Parse(string(ft.Tag))
+			panik(err)
+			var gfsRef *gridFSReference
+			for kk, vv := range imodel.gridFSReferences {
+				if strings.HasPrefix(kk, ft.Name) {
+					gfsRef = &vv
+					break
+				}
+			}
+			var inner = func(b *mongo.GridFSBucket, it reflect.Value) error {
+				filename := parseFmt(gfsRef.FilenameFmt, it.Interface())
+				contents := GridFSFile{}
+				curs, err2 := b.Find(context.TODO(), bson.M{"filename": filename})
+
+				if !errors.Is(err2, mongo.ErrNoDocuments) {
+					_ = curs.Decode(&contents)
+					if !reflect.ValueOf(contents).IsZero() {
+						return b.Delete(context.TODO(), contents.ID)
+					}
+				}
+				return nil
+			}
+			if gfsRef != nil {
+				b := bucket(*gfsRef)
+				if fv.Kind() == reflect.Slice {
+					for j := 0; j < fv.Len(); j++ {
+						lerr := inner(b, fv.Index(j))
+						if lerr != nil {
+							return lerr
+						}
+					}
+				} else if fv.Kind() == reflect.Struct {
+					lerr := inner(b, fv)
+					if lerr != nil {
+						return lerr
+					}
+				} else {
+					lerr := inner(b, el)
+					if lerr != nil {
+						return lerr
+					}
+				}
+			}
+			err = gridFsDel(fv.Interface(), imodel)
+			if err != nil {
+				return err
+			}
+		}
+	case reflect.Slice:
+		for i := 0; i < el.Len(); i++ {
+			rerr = gridFsDel(el.Index(i).Interface(), imodel)
+			if rerr != nil {
+				return rerr
+			}
+		}
+	default:
+		break
+	}
+	return rerr
+}
+
 func gridFsSave(val any, imodel Model) error {
 	var rerr error
 	v := reflect.ValueOf(val)