implement ExprMapper for File

pkg/files/file.go

@@ -47,6 +47,17 @@ func (f *File) SetURLWithTemplate(t *template.Template) error {
 	return nil
 }
 
+func (f File) ToExprMap() map[string]interface{} {
+	return map[string]interface{}{
+		"id":        f.ID,
+		"name":      f.Name,
+		"size":      f.Size,
+		"mime_type": f.MimeType,
+		"url":       f.URL,
+		"key":       f.Key,
+	}
+}
+
 func NewFile(name, mimeType string, size int, temp bool) *File {
 	i := id.GenerateNewID()
 	if temp {