Converting string to map in dart

 If you can change the string to valid JSON, you can use

import 'dart:convert';
...
Map valueMap = json.decode(value);
// or
Map valueMap = jsonDecode(value);

The string would need to look like

{"first_name" : "fname","last_name" : "lname","gender" : "male", "location" : { "state" : "state", "country" : "country", "place" : "place"} }