create method
Implementation
String create(String fid, User user) {
final dir = p.join(_root, historyDir, fid);
final file = p.join(dir, 'createdInfo.json');
final d = Directory(dir);
if (!d.existsSync()) {
d.createSync(recursive: true);
}
File(file).writeAsStringSync(json.encode({
'created': now,
'uid': user.id,
'uname': user.name,
}));
return file;
}