Develop Reference

Is there a way to use the same globalkey in multiple widgets?? in flutter

So I'm relatively new to flutter and I've been trying to dynamically add Sections(TextFormFields) that are represented in a form that has Form.Helper as its child and in the process to get the saveAndValidate method to work i had to use a GlobalKey to be able to access the currentState of its so i can validate and save user input and such, but whenever i try add another Section to the screen it display this error massage
════════ Exception caught by widgets library ═══════════════════════════════════
Multiple widgets used the same GlobalKey.
════════════════════════════════════════════════════════════════════════════════
here is the code I wrote and I'd appreciate any help in solving this error please.
#1- the code for the model I used:
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
class AddCourse with ChangeNotifier {
String? sectionName;
List<String>? sections;
List<dynamic>? addVids;
AddCourse({this.sectionName, this.sections, this.addVids});
/*where we save our values later to push them to firbase/database*/
Map<String, dynamic> toJson() {
final Map<String, dynamic> sectionData = <String, dynamic>{};
sectionData['Section #'] =
sections; // where current section number is saved and is stored dynamicly and updates as user adds more or less sections.
sectionData['Section Name'] =
sectionName; // where the input of the textformfield is saved and to be later pushed to the database and also is stored in a list so it can hold multiple section names as such.
return sectionData;
}
/* this is another model data for a functionality thats not implemented yet*/
Map<dynamic, dynamic> toJson2() {
final Map<dynamic, dynamic> vidData = <dynamic, dynamic>{};
vidData['Videos #'] = addVids;
return vidData;
}
}
#2 this the code for the form I created
import 'package:flutter/material.dart';
import 'package:snippet_coder_utils/FormHelper.dart';
import '../provider/course_add_model.dart';
class CourseCardBody extends StatefulWidget {
const CourseCardBody({
Key? key,
}) : super(key: key);
#override
State<CourseCardBody> createState() => _CourseCardBodyState();
}
class _CourseCardBodyState extends State<CourseCardBody> {
/* this is where i set up my global key that has the type of GlobalKey<FormState>*/
/*State associated with a [Form] widget. such as textformfields/forms/textfields..etc// the use of the (FormState) is to be able to Access the Functions "save"/"validate"/"reset" as to use them with forms/textformfields that you want to validate thier input or save it*/
GlobalKey<FormState> globalkey = GlobalKey();
AddCourse coursesModel = AddCourse();
#override
void initState() {
super.initState();
coursesModel.sections = List<String>.empty(growable: true);
coursesModel.sections?.add("");
// adds empty sections to the list of sections when the add button is used
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Add Courses'),
centerTitle: true,
),
body: ListView.separated(
shrinkWrap: true,
physics: const ScrollPhysics(),
itemBuilder: ((context, index) => Column(
children: [
_uiWidget(index),
Center(
// the submit button here needs some work to only be show once but for now sorry for this annoying button.
child: FormHelper.submitButton('Save', () {
if (validateAndSave()) {
print(coursesModel.toJson());
}
}),
),
],
)),
separatorBuilder: ((context, index) => const Divider()),
itemCount: coursesModel.sections!.length,
),
);
}
Widget _uiWidget(index) {
/* this form here is the parent of form fields/Formhelper widgets as seen below*/
return Form(
/* -- note here--
if we use a UniqueKey()
instead of our globalkey
here and comment the ValidateAndSave() function here
the form will work in terms of adding and removing sections
but we won't be able to either
save content/input of the user in the fields or
either validate
them so that sucks. */
/*this form is where global key is first used*/
key: globalkey,
child: SingleChildScrollView(
child: Column(
mainAxisSize: MainAxisSize.max,
mainAxisAlignment: MainAxisAlignment.start,
crossAxisAlignment: CrossAxisAlignment.start,
children: [
_sectionsContainer(index),
Row(
crossAxisAlignment: CrossAxisAlignment.end,
children: [
Flexible(
flex: 1,
fit: FlexFit.loose,
child: FormHelper.inputFieldWidgetWithLabel(
context,
'Add Section$index',
'',
'Section Title',
(onValidate) {
if (onValidate.isEmpty) {
return 'section ${index + 1} name cant be empty';
}
return null;
},
(onSavedVal) {
coursesModel.sections![index++] = index.toString();
onSavedVal = index;
},
onChange: (onChangedval) {
coursesModel.sectionName = onChangedval;
},
initialValue: coursesModel.sectionName ?? "",
borderColor: Colors.black,
borderFocusColor: Colors.black,
fontSize: 14,
labelFontSize: 14,
validationColor: Colors.redAccent,
),
),
Visibility(
visible: index == coursesModel.sections!.length - 1,
child: IconButton(
onPressed: () {
addEmailControl();
},
icon: const Icon(
Icons.add_circle,
color: Colors.greenAccent,
),
),
),
Visibility(
visible: index > 0,
child: SizedBox(
width: 35,
child: IconButton(
onPressed: () {
removeEmailControl(index);
},
icon: const Icon(
Icons.remove_circle,
color: Colors.redAccent,
),
),
),
),
],
),
],
),
),
);
}
Widget _sectionsContainer(index) {
/* the widget used to create the current section displayed on the top left of each textformfields*/
return Column(
children: [
Padding(
padding: const EdgeInsets.all(10),
child: Text(
'Section ${index + 1}',
textAlign: TextAlign.left,
style: const TextStyle(
fontSize: 14,
fontWeight: FontWeight.bold,
),
),
),
],
);
}
void addEmailControl() {
setState(() {
coursesModel.sections!.add('');
});
}
void removeEmailControl(index) {
setState(() {
if (coursesModel.sections!.length > 1) {
coursesModel.sections!.removeAt(index);
}
});
}
bool validateAndSave() {
/* we're especially using the <FormState> that is provided by the Globalkey to be able access the currentState of widget/form that has the global key in order to either validate or save the textformfields input or both in the same time*/
// validate each form
if (globalkey.currentState!.validate()) {
// If all data are correct then save data to out variables
// save each form
globalkey.currentState!.save();
return true;
} else {
return false;
}
}
}
I'm trying my best to figure it out on my own as I want to know how to solve this problem properly and where did I go wrong, and any help is very much appreciated thank you!

I suggest to create List<GlobalKey> variable. When you dynamically add or delete sub forms, you add or remove list items accordingly. It is impossible to use same GlobalKey for multiple widgets. So you need to create separate GlobalKeys for each form.

You may create a file of Global variables that may be shared across multiple files to ensure you are using a single instance.
Example globals.dart file
GlobalKey<SomeState> myGlobalKey = GlobalKey<SomeState>();
Example of implementation inside main.dart (or whatever file)
import './[path-to-globals]/globals.dart' // enter the appropriate path for your project
... // some code
Form(
key: myGlobalKey,
... // code
)
... // maybe more code

Flutter: ListView.builder + MultiImagePicker2

Im currently working on an app where it gets the pictures from galleries, then listing them out. But i cant seem to get it right. Currently facing an issue where i get the error
"_TypeError (type 'Future' is not a subtype of type 'Widget')".
any ideas
// ignore_for_file: prefer_const_constructors
import 'package:flutter/material.dart';
import 'package:multi_image_picker2/multi_image_picker2.dart';
import 'package:image_picker/image_picker.dart';
import 'package:permission_handler/permission_handler.dart';
class TestPage extends StatefulWidget {
const TestPage({Key? key}) : super(key: key);
#override
_TestPageState createState() => _TestPageState();
}
class _TestPageState extends State<TestPage> {
List<Asset> claims = <Asset>[];
final ImagePicker imgpicker = ImagePicker();
List<Asset>? imagefiles;
loadLimitedImages() async {
try {
var pickedfiles = await MultiImagePicker.pickImages(maxImages: 3);
if (pickedfiles != null) {
setState(() {
imagefiles = pickedfiles;
});
} else {
print("No image is selected.");
}
} catch (e) {
print("error while picking file.");
}
}
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
appBar: AppBar(
title: Text(
'Testing Functions',
style: TextStyle(color: Colors.black),
),
centerTitle: true,
backgroundColor: Colors.white,
iconTheme: IconThemeData(color: Colors.black),
),
body: SingleChildScrollView(
child: Padding(
padding: EdgeInsets.all(10),
child: Center(
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
imagefiles != null ? loadLimitedImages() : Container(),
imagefiles?.length == 3
? Container()
: IconButton(
onPressed: () => loadLimitedImages(),
icon: Icon(Icons.camera_enhance),
iconSize: 100,
),
],
),
),
),
),
);
}
}
I can only have 3 max images and it must be stacked in a row, when the images are picked, it goes back to the screen. If 3 images are showing, the camera icon dissapears, if not it will be beside the picked images if less than 3.

You get this error because of the following line in your build() method.
imagefiles != null ? loadLimitedImages() : Container(),
Here you call loadLimitedImages() which will return a Future, which is not a Widget. That method does not return anything, so this won't work in the way you try to use it.
If I understand it correctly, you want to pick 3 images, that operation should be a result of an action, e.g. a user taps a button to pick images. That is where you can call your loadLimitedImages() method. You shouldn't call such a method inside the build() method, since it could run frequently. The build() method's purpose is to build the UI based on the current state.
If you need to pick images without user interaction you can initiate it in the initState() of your State.

i want the animated container content change when pressed on it like that

when pressed on quick search the container should expand like this and I don't want to use expandable or any other widget because I want to use the animation of animated container when opened and closed

All credit goes to this post answer: How to create an animated container that hide/show widget in flutter
Here is a Complete Working Code:
// ignore_for_file: prefer_const_constructors
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
// This is the theme of your application.
//
// Try running your application with "flutter run". You'll see the
// application has a blue toolbar. Then, without quitting the app,
try
// changing the primarySwatch below to Colors.green and then invoke
// "hot reload" (press "r" in the console where you ran "flutter run",
// or simply save your changes to "hot reload" in a Flutter IDE).
// Notice that the counter didn't reset back to zero; the
application
// is not restarted.
primarySwatch: Colors.blue,
),
home: const MyHomePage(title: 'Animated Container Demo'),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({Key? key, required this.title}) : super(key: key);
// This widget is the home page of your application. It is stateful,
meaning
// that it has a State object (defined below) that contains fields that
affect
// how it looks.
// This class is the configuration for the state. It holds the values
(in
this
// case the title) provided by the parent (in this case the App widget)
and
// used by the build method of the State. Fields in a Widget subclass
are
// always marked "final".
final String title;
#override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
double _height = 50.0;
bool _isExpanded = false;
Future<bool> _showList() async {
await Future.delayed(Duration(milliseconds: 300));
return true;
}
#override
Widget build(BuildContext context) {
// This method is rerun every time setState is called, for instance as
done
// by the _incrementCounter method above.
//
// The Flutter framework has been optimized to make rerunning build
methods
// fast, so that you can just rebuild anything that needs updating
rather
// than having to individually change instances of widgets.
return Scaffold(
appBar: AppBar(
// Here we take the value from the MyHomePage object that was
created by
// the App.build method, and use it to set our appbar title.
title: Text(widget.title),
),
body: AnimatedContainer(
duration: Duration(milliseconds: 300),
height: _height,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(5),
color: Colors.grey,
),
width: MediaQuery.of(context).size.width - 100,
padding: EdgeInsets.only(left: 15, right: 15),
child: Column(
children: [
Padding(
padding: const EdgeInsets.only(top: 10),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
Text('Title'),
InkWell(
onTap: () {
if (!_isExpanded) {
setState(() {
_height = 300;
_isExpanded = true;
});
} else {
setState(() {
_height = 50;
_isExpanded = false;
});
}
},
child: Container(
height: 30,
width: 40,
color: Colors.red,
child:
!_isExpanded ? Icon(Icons.add) :
Icon(Icons.remove),
),
),
],
),
),
_isExpanded
? FutureBuilder(
future: _showList(),
/// will wait untill box animation completed
builder: (context, snapshot) {
if (!snapshot.hasData) {
return SizedBox();
}
return ListView.builder(
itemCount: 10,
shrinkWrap: true,
itemBuilder: (context, index) {
return Text('data'); // your custom UI
},
);
})
: SizedBox.shrink(),
],
),
));
}
}

use expandable: flutter pub add expandable,
check the documentation here.

How to implement a swipe to delete listview to remove data from firestore

Im very new to flutter and dart so this might be a basic question. However, what I would like to know is how to implement a swipe to delete method in a listview to delete data from firestore too.
I tried using the Dissmissible function but i dont understand how to display the list and I cant seem to understand how to remove the selected data as well.
This here is my dart code
Widget build(BuildContext context) {
return new Scaffold(
resizeToAvoidBottomPadding: false,
appBar: new AppBar(
centerTitle: true,
automaticallyImplyLeading: false,
title: Row(mainAxisAlignment: MainAxisAlignment.spaceBetween,children:
<Widget>[
Text("INVENTORY",textAlign: TextAlign.center,) ,new IconButton(
icon: Icon(
Icons.home,
color: Colors.black,
),
onPressed: () {
Navigator.push(
context,
SlideLeftRoute(widget: MyHomePage()),
);
})]),
),body: ListPage(),
);
}
}
class ListPage extends StatefulWidget {
#override
_ListPageState createState() => _ListPageState();
}
class _ListPageState extends State<ListPage> {
Future getPosts() async{
var firestore = Firestore.instance;
QuerySnapshot gn = await
firestore.collection("Inventory").orderBy("Name",descending:
false).getDocuments();
return gn.documents;
}
#override
Widget build(BuildContext context) {
return Container(
child: FutureBuilder(
future: getPosts(),
builder: (_, snapshot){
if(snapshot.connectionState == ConnectionState.waiting){
return Center(
child: Text("Loading"),
);
}else{
return ListView.builder(
itemCount: snapshot.data.length,
itemBuilder:(_, index){
return EachList(snapshot.data[index].data["Name"].toString(),
snapshot.data[index].data["Quantity"]);
});
}
}),
);
}
}
class EachList extends StatelessWidget{
final String details;
final String name;
EachList(this.name, this.details);
#override
Widget build(BuildContext context) {
// TODO: implement build
return new Card(
child:new Container(
padding: EdgeInsets.all(8.0),
child: new Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
new Row(
children: <Widget>[
new CircleAvatar(child: new Text(name[0].toUpperCase()),),
new Padding(padding: EdgeInsets.all(10.0)),
new Text(name, style: TextStyle(fontSize: 20.0),),
],
),
new Text(details, style: TextStyle(fontSize: 20.0))
],
),
),
);
}
}

You should use Dismissible widget. I used it for an inbox list retrieved from Firestore. Inside your EachList return something like this
return Dismissible(
direction: DismissDirection.startToEnd,
resizeDuration: Duration(milliseconds: 200),
key: ObjectKey(snapshot.documents.elementAt(index)),
onDismissed: (direction) {
// TODO: implement your delete function and check direction if needed
_deleteMessage(index);
},
background: Container(
padding: EdgeInsets.only(left: 28.0),
alignment: AlignmentDirectional.centerStart,
color: Colors.red,
child: Icon(Icons.delete_forever, color: Colors.white,),
),
// secondaryBackground: ...,
child: ...,
);
});
IMPORTANT: in order to remove the list item you'll need to remove the item from the snapshot list as well, not only from firestore:
_deleteMessage(index){
// TODO: here remove from Firestore, then update your local snapshot list
setState(() {
snapshot.documents.removeAt(index);
});
}
Here the doc: Implement Swipe to Dismiss
And here a video by Flutter team: Widget of the week - Dismissilbe

You can use the flutter_slidable package to achieve the same.
You can also check out my Cricket Team on Github in which I have did the same you want to achieve, using same package.
Example for how to use package are written here.

I'd like to add that when deleting a document from Firestore, no await is needed as the plugin automatically caches the changes and then syncs them up when there is a connection again.
For instance, I used to use this method
Future deleteWatchlistDocument(NotifierModel notifier) async {
final String uid = await _grabUID();
final String notifierID = notifier.documentID;
return await _returnState(users.document(uid).collection(watchlist).document(notifierID).delete());
}
in which I was waiting for the call to go through, however this prevented any other call to go through and only allowed one. Removing this await tag however solved my issue.
Now I can delete documents offline, and the changes will sync up with Firestore when a connection is regained. It's pretty cool to watch in the console.
I'd recommend watching this video about offline use with Firestore

Manage state of one page from another class

I'm building an app for training in Flutter and I'm actually stuck in the filter functionality.
I have a ListView where I fetch data from TheMovieDB API and a ModalBottomSheet with three FilterChips for selecting the filter criteria (popular, top rated and latest movies).
And here's where I'm stuck. I want to call the "_loadNextPage()" method when the user presses the "Done" button in the ModalBottomSheet through "performUpdate()" but I can't do it because they're not in the same class.
I'll post the code down below for better understanding.
class _HomePageState extends State<HomePage> {
RequestProvider _requestProvider = new RequestProvider();
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("FluttieDB"),
actions: <Widget>[
IconButton(
icon: Icon(Icons.filter_list),
onPressed: () => buildFilterBottomSheet(),
)
],
),
body: MovieList(_requestProvider, _currentFilter),
);
}
void buildFilterBottomSheet() {
showModalBottomSheet(
context: context,
builder: (builder) {
return Container(
height: 150.0,
decoration: BoxDecoration(color: Colors.white),
child: Column(
children: <Widget>[
buildFilterTitle(context),
Expanded(
child: _FilterChipRow(),
),
],
),
);
});
}
Widget buildFilterTitle(BuildContext context) {
return Container(
padding: const EdgeInsets.symmetric(horizontal: 12.0, vertical: 6.0),
alignment: Alignment.centerLeft,
height: 46.0,
decoration: BoxDecoration(color: Colors.blue),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
mainAxisSize: MainAxisSize.max,
children: <Widget>[
Text(
"Filter by",
style: TextStyle(color: Colors.white, fontSize: 20.0),
),
OutlineButton(
onPressed: () => performUpdate(context),
padding: const EdgeInsets.all(0.0),
shape: const StadiumBorder(),
child: Text(
"Done",
style: TextStyle(color: Colors.white),
),
),
],
),
);
}
void performUpdate(BuildContext context) {
MovieList _movieList = new MovieList(_requestProvider, _currentFilter);
_movieList.createState()._loadNextPage();
Navigator.pop(context);
}
}
class MovieList extends StatefulWidget {
MovieList(this.provider, this.currentFilter, {Key key}) : super(key: key);
final RequestProvider provider;
final String currentFilter;
#override
_MovieListState createState() => new _MovieListState();
}
class _MovieListState extends State<MovieList> {
List<Movie> _movies = List();
int _pageNumber = 1;
LoadingState _loadingState = LoadingState.LOADING;
bool _isLoading = false;
_loadNextPage() async {
_isLoading = true;
try {
var nextMovies = await widget.provider
.provideMedia(widget.currentFilter, page: _pageNumber);
setState(() {
_loadingState = LoadingState.DONE;
_movies.addAll(nextMovies);
_isLoading = false;
_pageNumber++;
});
} catch (e) {
_isLoading = false;
if (_loadingState == LoadingState.LOADING) {
setState(() => _loadingState = LoadingState.ERROR);
}
}
}
#override
void initState() {
super.initState();
_loadNextPage();
}
#override
Widget build(BuildContext context) {
switch (_loadingState) {
case LoadingState.DONE:
return ListView.builder(
itemCount: _movies.length,
itemBuilder: (BuildContext context, int index) {
if (!_isLoading && index > (_movies.length * 0.7)) {
_loadNextPage();
}
return MovieListItem(_movies[index]);
});
case LoadingState.ERROR:
return Center(
child: Text("Error retrieving movies, check your connection"));
case LoadingState.LOADING:
return Center(child: CircularProgressIndicator());
default:
return Container();
}
}
}
As you can see, I did some experiments in the performUpdate() but it doesn't refresh the ListView with the selected option in the filters and I don't think it's the best way to achieve what I want.
Thanks and sorry if the question is a bit dumb. I'm a little bit newbie in Flutter.

Redux is a great state management library that originated with React and JS, but has been ported to Dart, and has a flutter specific library as well. Redux is a very powerful framework which uses a pub/sub system to allow your view to subscribe to changes to the model, while using a system of "actions" and "reducers" to update the model.
A great tutorial for getting up and running with Redux in Flutter can be found here
Alternatively you could look into the scoped model, which is another state management library for flutter. The scoped model is less capable, but for simple use cases may be more than adequate.
Further reading:
Understand and choose a state management solution
You Might Not Need Redux