How to save Text Input data locally in json format through shared preferences in Flutter?

Question

I am creating app in Flutter in which I need to save data coming from textinput through shared preferences in JSON Format. I searched about JSON serialization in dart before saving it to the shared preferences I created a Model class for serializing JSON which is given below :

class ServerData {
  final String servername;
  final String serverurl;
  final String username;
  final String password;

  ServerData(this.servername, this.serverurl, this.username, this.password);

  ServerData.fromJson(Map<String, dynamic> json)
      : servername = json['servername'],
        serverurl = json['serverurl'],
        username = json['username'],
        password = json['password'];

  Map<String, dynamic> toJson() => {
    'servername' : servername,
    'serverurl' : serverurl,
    'username' : username,
    'password' : password
  };
}

Now I need to store the input data with the help of TextEditingController :

final _servername = TextEditingController();
final _serverurl = TextEditingController();
final _username = TextEditingController();
final _password = TextEditingController();

ServerData serverData = new ServerData(_servername.text,_serverurl.text,_username.text,_password.text); 

/* I am getting error of "Only static members can be accessed in Initializers" in above code */

String encodeData = jsonEncode(serverData); /* Not able to use encode and decode due to error in ServerData object */

I need help regarding this.

You can watch solution, but I don't understand. All of your controllers are just created and empty. So, you are creating ServerData with empty strings — Andrii Turkovskyi
– Andrii Turkovskyi, Commented Jul 31, 2019 at 11:15
Actually I was trying to store all the textinput in serverdata through textediting controller but I am doing it in wrong because I am initialising it with empty text inputs. So do I need to setState first for all the inputs? — ahd786
– ahd786, Commented Aug 1, 2019 at 8:59
You have to create ServerData in moment when you exactly want to save data. It can by on pressing the button or on changing text in TextField — Andrii Turkovskyi
– Andrii Turkovskyi, Commented Aug 1, 2019 at 9:17
Yes, I was able to store data now json format Thanks for that. But what if I want to store another Json data in the same key of shared preference and it should look like a list. — ahd786
– ahd786, Commented Aug 2, 2019 at 8:14
It's not the good practice - store different formats in one list. It would be better to save with different keys. But if you really want - you can put your data to jsonArray and save it, so it will be list — Andrii Turkovskyi
– Andrii Turkovskyi, Commented Aug 2, 2019 at 8:42

Andrii Turkovskyi · Accepted Answer · 2019-07-31 11:11:54Z

1

You have to move initialization inside initState:

ServerData serverData;
String encodeData;

@override
void initState() {
  serverData = new ServerData(_servername.text,_serverurl.text,_username.text,_password.text);
  encodeData = jsonEncode(serverData);
  super.initState();
}

answered Jul 31, 2019 at 11:11

Andrii Turkovskyi

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