I am using shared_preferences: ^2.0.15 and saving my values locally.
When I change my screen and get my values, I get an error.
How can I initialize SharedPreferences correctly?
Video
late SharedPreferences _preferences;
#override
void initState() {
super.initState();
getLocalData();
}
Future getLocalData() async {
_preferences = await SharedPreferences.getInstance();
}
I've checked the video you shared.
You're just missing to call the getLocalData method inside the LoginViewModel.
I'd suggest adding a line inside your loginRequest method to call getLocalData method. Well, don't forget to await.
await getLocalData();
That's it :)
actually you are not fetching data from your shared preference
you have to get the data that u saved
first set data that you want to save
addStringToSF() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
prefs.setString('email', "email#email.com");
}
then in your second screen you can get your data
late SharedPreferences _preferences;
late String email;
#override
void initState() {
super.initState();
getLocalData();
}
Future getLocalData() async {
_preferences = await SharedPreferences.getInstance();
// for exemple you saved a string value with key ='email'
email= _preferences.getString('email');
}
check this : https://medium.flutterdevs.com/using-sharedpreferences-in-flutter-251755f07127
Related
In my code at the home page fetch user name from firestore database and that's display nicely in UI. I want pass that name to shared preference function and store there and use that name in another pages also.
Code
home page code ( initstate and send name to saveNameToSharedPreferences() method )
#override
void initState() {
super.initState();
getData();
fetchName();
storeName();
}
void storeName() {
String displayName = '${user?.displayName}';
return displayName.saveNameToSharedPreferences();
}
SharedPreferences code
import 'package:shared_preferences/shared_preferences.dart';
String? _displayName;
String? get displayName => _displayName;
Future saveNameToSharedPreferences() async {
final SharedPreferences sn = await SharedPreferences.getInstance();
await sn.setString('displayName', _displayName!);
}
Future getNameFromSharedPreferences() async {
final SharedPreferences sn = await SharedPreferences.getInstance();
_displayName = sn.getString('displayName');
}
How to solve this ?
You are calling function as an extension. Try to pass parameter instead.
Make the following changes
Future saveNameToSharedPreferences(String displayName) async {
final SharedPreferences sn = await SharedPreferences.getInstance();
await sn.setString('displayName', displayName);
}
And call it as
void storeName() {
String displayName = '${user?.displayName}';
saveNameToSharedPreferences(displayName);
}
I've create an initState in my page and call callData to get favId (type : List) every I open this page. But, when the application start, my compiler show this error message :
_TypeError (type 'List<String>' is not a subtype of type 'String')
and this is my getData's function :
getData(favId) async {
SharedPreferences pref = await SharedPreferences.getInstance();
return pref.getStringList(favId);
}
also this is my saveData's function :
void saveData() async {
SharedPreferences pref = await SharedPreferences.getInstance();
pref.setStringList("id", favId);
}
How to fix this problem and I can call getData every I open this page in my application?
Thank you :)
if you want to save and retrieve List to and from SharedPreferences, you to use same key to save and retrieve the value.
here is a simple example,
const favKey = 'favoriteKey';
To save data,
void saveData(String favKey, List<String> favorites) async {
SharedPreferences pref = await SharedPreferences.getInstance();
pref.setStringList(favKey,favorites);
}
To retrive data,
getData(String favKey) async {
SharedPreferences pref = await SharedPreferences.getInstance();
return pref.getStringList(favKey);
}
Note: You need to use same key to set and get data using SharedPreference.
"id" is a String, you need to store a List<String> into setStringList
There are the steps if you want to add an item to the list:
List<String> ids = await getData(favId);
ids.add("id");
saveData(ids, favId);
then change the saveData() to
void saveData(ids, favId) async {
SharedPreferences pref = await SharedPreferences.getInstance();
pref.setStringList(ids, favId);
}
getData()
List<String> getData(favId) async {
SharedPreferences pref = await SharedPreferences.getInstance();
return pref.getStringList(favId);
}
I have a simple question regering the shared_preferences package in flutter.
Is it safe to get an instance of SharedPreferences and store that for future use or is it best to always get a new reference each time?
To clarify, which of these two are the proper or best way of doing it?
SharedPreferences preferences;
void init() async {
preferences = await SharedPreferences.getInstance();
}
void setValue(String key, String value) async{
await preferences.setString(key, value);
}
void setValue(String key, String value) async {
final preferences = await SharedPreferences.getInstance();
await preferences.setString(key, value);
}
I'm working with SharedPreferences to make feature offline bookmark News . i can saved and fetching single value with this code :
Saved Value
void _testingSavePref(String judulBerita) async {
SharedPreferences pref = await SharedPreferences.getInstance();
pref.setString("tokenbookmark", judulBerita);
}
Fetching Value
#override
void initState() {
super.initState();
setState(() {
_testingLoadPref();
});
}
_testingLoadPref() async {
SharedPreferences pref = await SharedPreferences.getInstance();
setState(() {
tokenBookmark = pref.getString("tokenbookmark");
});
}
Everything is oke , but it's possible to saved and fetching multiple value with SharedPreferences ?
Example, i have 2 or more data, i want all data saved and not overwrite.
Thank's
Updated Code:
For Saving Values
void _testingSavePref(List<String> judulBerita) async {
SharedPreferences pref = await SharedPreferences.getInstance();
await pref.setStringList("tokenbookmark", judulBerita); //judulBerita is a list of string now
}
For Fetching Values
#override
void initState() {
super.initState();
setState(() {
_testingLoadPref();
});
}
_testingLoadPref() async {
SharedPreferences pref = await SharedPreferences.getInstance();
setState(() {
final List<String>? tokenBookmark = pref.getStringList("tokenbookmark");
});
}
Now, You can get the data from tokenBookmark list by below code
for(String s in tokenBookmark){
print(s);
}
You shouldn't use SharedPreferences to save that kind of data.
Use a local sql or nosql database (sqflite / sembast).
Also don't call setState inside the initState method is wrong and unnecessary.
I'm trying to to set a value from sharedpreferences to provider at application start.
this what I have so far, sharedpreferences to widget is working:
https://gist.github.com/andraskende/a19c806aeef0ce88e9a9cafa49660ab4#file-main-dart-L211-L223
Finally i figured out with trial and error... It can be done in the constructor as:
class BarcodeProvider with ChangeNotifier {
BarcodeProvider() {
setup();
}
void setup() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
String url = (await prefs.getString('url') ?? '');
_url = url;
notifyListeners();
}
......
}
// global variable, that can be accessed from anywhere
SharedPreferences sharedPrefs;
void main() async { // make it async
WidgetsFlutterBinding.ensureInitialized(); // mandatory when awaiting on main
sharedPrefs = await SharedPreferences.getInstance(); // get the prefs
// do whatever you need to do with it
runApp(MyApp()); // rest of your app code
}