converting string to map in dart

Make a wrapper class for the location where you define the methods fromMap, toMap

create two objects

class User {
  final String firstName;
  final String lastName;
  final String gender;
  final location;

  User({
    this.firstName,
    this.lastName,
    this.gender,
    this.location,
  });

  User.fromJson(Map json)
      : firstName = json['firstName'],
        lastName = json['lastName'],
        gender = json['gender'],
        location = Location.fromJson(json['location']);
}

class Location {
  final String state;
  final String country;
  final String place;

  Location({
    this.state,
    this.country,
    this.place,
  });

  Location.fromJson(Map json)
      : state = json['state'],
        country = json['country'],
        place = json['place'];
}

then use it like this

var user = User.fromJson(value);
print(user.firstName);

or convert it to list like this

var user = User.fromJson(value).toList();

That's not possible.

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"} }

You would have to change the way you create the string.

I'm guessing you are creating the string using the yourMap.toString() method. You should rather use json.encode(yourMap), which converts your map to valid JSON, which you can the parse with json.decode(yourString).