Set data in the app, which is retrive from firebase - flutter

Image is not coming but all the data in the firebase database is showing in the app.
import 'package:flutter/material.dart';
import 'Authentication.dart';
import 'photoUpload.dart';
import 'Posts.dart';
import 'package:firebase_database/firebase_database.dart';
// import 'package:flutter_blogapp/Authentication.dart';
// import 'package:flutter_blogapp/photoUpload.dart';
class HomePage extends StatefulWidget
{
HomePage
(
{
this.auth,
this.onSignedOut,
}
);
final AuthImplementation auth;
final VoidCallback onSignedOut;
#override
State<StatefulWidget> createState()
{
return _HomePageState();
}
}
class _HomePageState extends State<HomePage>
{
List<Posts> postsList = [];
#override
void initState()
{
super.initState();
DatabaseReference postsRef = FirebaseDatabase.instance.reference().child("Posts");
postsRef.once().then((DataSnapshot snap)
{
var KEYS = snap.value.keys;
var DATA = snap.value;
postsList.clear();
for(var individualKey in KEYS)
{
Posts posts = new Posts
(
DATA[individualKey]['image'],
DATA[individualKey]['description'],
DATA[individualKey]['data'],
DATA[individualKey]['time'],
);
postsList.add(posts);
}
setState(()
{
print('Length : $postsList.length');
});
});
}
void _logoutUser() async
{
try
{
await widget.auth.signOut();
widget.onSignedOut();
}
catch (e)
{
print(e.toString());
}
}
#override
Widget build(BuildContext context)
{
return new Scaffold
(
appBar: new AppBar
(
title: new Text('Home'),
),
body : new Container
(
child: postsList.length == 0 ? new Text(" No Post available ") : new ListView.builder
(
itemCount: postsList.length,
itemBuilder: (_, index)
//itemBuilder: (BuildContext _, int index ) //<-----
{
return PostsUI(postsList[index].image, postsList[index].description, postsList[index].date, postsList[index].time);
}
),
),
bottomNavigationBar: new BottomAppBar
(
color: Colors.pink,
child: new Container
(
margin: const EdgeInsets.only(left: 70.0, right: 70.0),
child: new Row
(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
mainAxisSize: MainAxisSize.max,
children: <Widget>
[
new IconButton
(
icon: new Icon(Icons.local_car_wash),
iconSize: 50,
color: Colors.white,
onPressed: _logoutUser,
),
new IconButton
(
icon: new Icon(Icons.add_a_photo),
iconSize: 50,
color: Colors.white,
onPressed: ()
{
Navigator.push
(
context,
MaterialPageRoute(builder: (context)
{
return new UploadPhotoPage();
})
);
},
),
],
),
),
),
);
}
// Designing Posts UI
Widget PostsUI(String image, String description, String date, String time)
{
return new Card
(
elevation: 10.0,
margin: EdgeInsets.all(15.0),
child: new Container
(
padding: new EdgeInsets.all(14.0),
child: new Column
(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>
[
new Row
(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>
[
new Text
(
date,
style: Theme.of(context).textTheme.subtitle,
textAlign: TextAlign.center,
),
new Text
(
time,
style: Theme.of(context).textTheme.subtitle,
textAlign: TextAlign.center,
), //<----
],
),
SizedBox(height: 10.0,),
new Image.network(image, fit:BoxFit.cover),
SizedBox(height: 10.0,),
new Text
(
description,
style: Theme.of(context).textTheme.subhead,
textAlign: TextAlign.center,
),
],
)
)
);
}
}
The following errors are showing:
═══════ Exception caught by image resource service
════════════════════════════ The following ArgumentError was thrown
resolving an image codec: Invalid argument(s): No host specified in
URI file:///image
When the exception was thrown, this was the stack
0 _HttpClient._openUrl (dart:_http/http_impl.dart:2276:9)
1 _HttpClient.getUrl (dart:_http/http_impl.dart:2197:48)
2 NetworkImage._loadAsync package:flutter/…/painting/_network_image_io.dart:84
3 NetworkImage.load package:flutter/…/painting/_network_image_io.dart:47
4 ImageProvider.resolve...
package:flutter/…/painting/image_provider.dart:327 ... Image provider:
NetworkImage("image", scale: 1.0) Image key: NetworkImage("image",
scale: 1.0)

The main part of the error message is:
Invalid argument(s): No host specified in URI file:///image
From this it looks like you're storing a local file:/// reference into the database, instead of a globally accessible URL (typically starting with http:// or https://).
The solution is in the code that writes to the database, to actually upload the image to a public storage place (such as to Firebase Storage) and then write the resulting download URL into the database.

Related

i can't get all the data from an api

i want to display some data that i receive from a web Api in the form of posts, most of that data gets displayed on the screen normally but all of a sudden an error arises and all the remaining posts become red.
the error i get:
The following NoSuchMethodError was thrown building:
The method '[]' was called on null.
Receiver: null
Tried calling: [](0)
When the exception was thrown, this was the stack
#0 Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5)
#1 _NewsScreenState.build.<anonymous closure>.<anonymous closure>
#2 SliverChildBuilderDelegate.build
package:flutter/…/widgets/sliver.dart:449
#3 SliverMultiBoxAdaptorElement._build
package:flutter/…/widgets/sliver.dart:1130
#4 SliverMultiBoxAdaptorElement.performRebuild.processElement
package:flutter/…/widgets/sliver.dart:1076
the way how i display the posts:
import 'package:flutter/material.dart';
class NewsFrame extends StatelessWidget {
final String title;
final String excerpt;
final String webUrl;
final String imageUrl;
final String publishedDateTime;
final String sourceName;
const NewsFrame(
{this.title,
this.excerpt,
this.webUrl,
this.imageUrl,
this.publishedDateTime,
this.sourceName});
String formatTime(String receivedDate) {
String date = receivedDate.substring(0, 11);
return "${date.substring(0, 4)}/${date.substring(5, 7)}/${date.substring(8, date.length-1)}";
}
void delayedMomemt() async {
await Future.delayed(Duration(milliseconds: 200));
print(this.title);
print(this.excerpt);
print(this.webUrl);
print(this.publishedDateTime);
print(this.imageUrl);
print(this.sourceName);
}
#override
Widget build(BuildContext context) {
this.delayedMomemt();
return Container(
decoration: BoxDecoration(color: Colors.green),
padding: const EdgeInsets.all(8),
margin: const EdgeInsets.all(8),
child: Column(
mainAxisSize: MainAxisSize.min,
children: [
Text(this.title),
this.imageUrl == null
? SizedBox(height: 0)
: Image.network(this.imageUrl),
Text(this.excerpt),
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
Text(this.publishedDateTime == null
? "No Date"
: this.formatTime(this.publishedDateTime)),
Text(this.sourceName ?? "Unknown")
],
)
],
),
);
}
}
how i send the data to the posts file:
class NewsScreen extends StatefulWidget {
#override
_NewsScreenState createState() => _NewsScreenState();
}
class _NewsScreenState extends State<NewsScreen> {
var articalsData;
#override
void initState() {
super.initState();
GetData getData = GetData();
this.articalsData = getData.getArticals();
}
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: ThmColors.lightBlueClr,
body: Stack(
children: [
FadedBg(img: "img21"),
Center(
child: FutureBuilder(
future: this.articalsData,
builder: (context, snapshot) {
if (snapshot.hasData) {
return Column(
children: [
SizedBox(height: MediaQuery.of(context).size.height / 6),
Expanded(
child: ListView.builder(
itemCount: snapshot.data['news'].length,
itemBuilder: (context, index) => NewsFrame(
title: snapshot.data['news'][index]['title'],
excerpt: snapshot.data['news'][index]['excerpt'],
webUrl: snapshot.data['news'][index]['webUrl'],
imageUrl: snapshot.data['news'][index]['images'][0]['url'],
publishedDateTime: snapshot.data['news'][index]['publishedDateTime'],
sourceName: snapshot.data['news'][index]['provider']['name'],
),
),
),
],
);
} else if (snapshot.hasError) {
return Column(
mainAxisSize: MainAxisSize.min,
children: [
Text('Oops! something went wrong.',
style: TextStyle(
fontSize: 20,
fontWeight: FontWeight.bold,
)),
Text('(Check out your: Signal, Internet, WiFi...)',
style: TextStyle(
fontSize: 15,
fontWeight: FontWeight.w500,
letterSpacing: -0.5)),
],
);
}
return LoadingRing();
},
),
),
Positioned(
top: 0,
child: UpperBar(titleTxt: "News"),
),
],
),
);
}
}
PLEASE HELP!
It looks like not every article has an images array, try checking if its null before getting the first image, if it is provide some sort of default image instead. Something like this:
imageUrl: getImage(snapshot.data['news'][index])
...
String getImage(data){
if (data['images'] == null || data['images'].isEmpty)
return 'default_image_url'
return data['images'][0]['url']
}

How to reformat the data from Blogger API in Flutter

I'm creating an app for my new blog, which is hosted on blogger.com. I've got the posts to get displayed in the app along with the images, but for some reason I can't get the text in the post to be formatted. It has just bunched it all together.
Here's how it looks in the blog & in the app:
How can I format this in my code so that it looks like it does in the blog?
Here's the code I'm using in the main.dart file:
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';
import 'package:html/parser.dart';
import 'pages/post_view.dart';
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return new MaterialApp(
title: 'Flutter Demo',
theme: new ThemeData(
primarySwatch: Colors.blue,
),
home: new MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
var _isLoading = true; //For progress bar
var posts;
var imgUrl;
//initialization
void initState() {
super.initState();
_fetchData();
}
//Function to fetch data from JSON
#override
_fetchData() async {
print("attempting");
final url =
"https://www.googleapis.com/blogger/v3/blogs/8902712678213444829/posts/?key=AIzaSyDpwI-kMZ_IxqAJVBKAVtWLOlaGQ5YLEuw";
final response = await http.get(url);
print(response.body);
if (response.statusCode == 200) {
//HTTP OK is 200
final Map items = json.decode(response.body);
var post = items['items'];
setState(() {
_isLoading = false;
this.posts = post;
});
}
}
#override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: new Text("Blogger"),
actions: <Widget>[
new IconButton(
icon: new Icon(Icons.refresh),
onPressed: () {
setState(() {
_isLoading = true;
});
_fetchData();
})
],
),
body: new Center(
child: _isLoading
? new CircularProgressIndicator()
: new ListView.builder(
itemCount: this.posts != null ? this.posts.length : 0,
itemBuilder: (context, i) {
final post = this.posts[i];
final postDesc = post["content"];
//All the below code is to fetch the image
var document = parse(postDesc);
//Regular expression
RegExp regExp = new RegExp(
r"(https?:\/\/.*\.(?:png|jpg|gif))",
caseSensitive: false,
multiLine: false,
);
final match = regExp
.stringMatch(document.outerHtml.toString())
.toString();
//print(document.outerHtml);
//print("firstMatch : " + match);
//Converting the regex output to image (Slashing) , since the output from regex was not perfect for me
if (match.length > 5) {
if (match.contains(".jpg")) {
imgUrl = match.substring(0, match.indexOf(".jpg"));
print(imgUrl);
} else {
imgUrl =
"https://www.googleapis.com/blogger/v3/blogs/8902712678213444829/posts/?key=AIzaSyDpwI-kMZ_IxqAJVBKAVtWLOlaGQ5YLEuw";
}
}
String description = document.body.text.trim();
//print(description);
return new Container(
padding:
const EdgeInsets.fromLTRB(16.0, 16.0, 16.0, 8.0),
child: new Column(
mainAxisAlignment: MainAxisAlignment.spaceAround,
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
new Container(
width: 500.0,
height: 180.0,
decoration: new BoxDecoration(
shape: BoxShape.rectangle,
image: new DecorationImage(
fit: BoxFit.fitHeight,
//check if the image is not null (length > 5) only then check imgUrl else display default img
image: new NetworkImage(imgUrl
.toString()
.length >
10
? imgUrl.toString()
: "https://www.googleapis.com/blogger/v3/blogs/8902712678213444829/posts/?key=AIzaSyDpwI-kMZ_IxqAJVBKAVtWLOlaGQ5YLEuw")),
),
),
new Padding(
padding:
const EdgeInsets.symmetric(vertical: 10.0),
child: new Text(
post["title"],
maxLines: 3,
style: new TextStyle(
fontSize: 18.0,
fontWeight: FontWeight.bold,
),
),
),
new Text(
description.replaceAll("\n", ", "),
maxLines: 2,
overflow: TextOverflow.ellipsis,
style: new TextStyle(fontSize: 15.0),
),
new Padding(
padding:
const EdgeInsets.symmetric(vertical: 16.0),
child: new RaisedButton(
child: new Text("READ MORE",style: new TextStyle(color: Colors.white),),
color: Colors.blue,
onPressed: () {
//We will pass description to postview through an argument
Navigator
.of(context)
.push(new MaterialPageRoute<Null>(
builder: (BuildContext context) {
return PostView(post['title'],description,imgUrl);
},
));
},
),
),
Divider(),
],
),
);
},
)));
}
}
And here's the code I'm using in the post_view.dart file:
import 'package:flutter/material.dart';
class PostView extends StatelessWidget {
var desc, title, image;
PostView(String title, String desc, String image) {
this.desc = desc;
this.title = title;
this.image = image;
}
#override
Widget build(BuildContext context) {
if (desc.toString().contains("\n\n\n\n")) {
desc = desc.toString().replaceAll("\n\n\n\n", "\n\n");
}
if (desc.toString().contains("\n\n\n")) {
desc = desc.toString().replaceAll("\n\n\n", "\n");
}
return new Scaffold(
appBar: new AppBar(
title: new Text("Blogger"),
),
body: new Container(
child: new SingleChildScrollView(
child: new Column(
children: <Widget>[
new Padding(
padding:
const EdgeInsets.symmetric(vertical: 16.0, horizontal: 16.0),
child: new Text(
title,
style: new TextStyle(
fontSize: 22.0,
fontWeight: FontWeight.bold,
),
),
),
new Padding(
padding:
const EdgeInsets.symmetric(vertical: 16.0, horizontal: 16.0),
child: new Container(
width: 500.0,
height: 180.0,
decoration: new BoxDecoration(
shape: BoxShape.rectangle,
image: new DecorationImage(
fit: BoxFit.fill,
//check if the image is not null (length > 5) only then check imgUrl else display default img
image: new NetworkImage(image.toString().length > 10
? image.toString()
: "https://www.googleapis.com/blogger/v3/blogs/8902712678213444829/posts/?key=AIzaSyDpwI-kMZ_IxqAJVBKAVtWLOlaGQ5YLEuw")),
),
),
),
new Padding(
padding:
const EdgeInsets.symmetric(vertical: 16.0, horizontal: 16.0),
child: new Text(
desc,
style: new TextStyle(
fontSize: 18.0,
),
),
),
],
))),
);
}
}
EDITED:
Here's what get's printed in the console when I hot reload the app:
I/flutter ( 9778): attempting
I/flutter ( 9778): {
I/flutter ( 9778): "kind": "blogger#postList",
I/flutter ( 9778): "items": [
I/flutter ( 9778): {
I/flutter ( 9778): "kind": "blogger#post",
I/flutter ( 9778): "id": "3086822326789809431",
I/flutter ( 9778): "blog": {
I/flutter ( 9778): "id": "8902712678213444829"
I/flutter ( 9778): },
I/flutter ( 9778): "published": "2020-06-15T00:22:00-07:00",
I/flutter ( 9778): "updated": "2020-06-15T22:19:56-07:00",
I/flutter ( 9778): "url": "http://lessmeatapp.blogspot.com/2020/06/mushroom-tagine.html",
I/flutter ( 9778): "selfLink": "https://www.googleapis.com/blogger/v3/blogs/8902712678213444829/posts/3086822326789809431",
I/flutter ( 9778): "title": "Dummy Post 3",
I/flutter ( 9778): "content": "\u003cbr /\u003e\u003cdiv class=\"separator\" style=\"clear: both; text-align: center;\"\u003e\u003ca href=\"https://1.bp.blogspot.com/-Vv9KcxNHxhU/XuhVnskHvCI/AAAAAAAAAGw/z7tH271PrIEvkQam74G497Gw4A-eFondACK4BGAsYHg/s1400/DD-Grunge-United-Kingdom-Flag-88837-Preview.jpg\" imageanchor=\"1\" style=\"margin-left: 1em; margin-right: 1em;\"\u003e\u003cimg border=\"0\" data-original-height=\"980\" data-original-width=\"1400\" src=\"https://1.bp.blogspot.com/-Vv9KcxNHxhU/XuhVnskHvCI/AAAAAAAAAGw/z7tH271PrIEvkQam74G497G
I/flutter ( 9778): https://1.bp.blogspot.com/-Vv9KcxNHxhU/XuhVnskHvCI/AAAAAAAAAGw/z7tH271PrIEvkQam74G497Gw4A-eFondACK4BGAsYHg/s1400/DD-Grunge-United-Kingdom-Flag-88837-Preview
I/flutter ( 9778): https://1.bp.blogspot.com/-hvzDDsO44FI/XuhWvqDjRwI/AAAAAAAAAHI/mBjWane0s5wtdJnkLDrNrmyprVoNeWDagCK4BGAsYHg/s1400/DD-Patriotic-Retro-Background-33092-Preview
I/flutter ( 9778): https://1.bp.blogspot.com/-efv2-Ikiyr8/XuhX-YLtDDI/AAAAAAAAAH0/JJE2mrOU-HMsq6Adu1whv5b3W10yqkRlQCK4BGAsYHg/s1400/20
in response, content section is HTML
and for render HTML in the flutter, you should use fultter_html package
you can find it in this link
and with this, you don't need export images from your content
if you have any question ask me in comments
in your PostView build method pass description variable to HTML widget:
Html(
data: description,
//Optional parameters:
backgroundColor: Colors.white70,

Flutter: Multiple Instances of Shared Preferences?

I am having a problem with SharedPreferences and multiple Modules I am generating on a Form using ListView.builder
The form is basically asking for some parents details and their childs details - by default the form assumes the parent has one child, but more can be added by clicking a button. The ChildModule has the ability to "close" but when "re-opened" the data doesn't persist, hence using SharedPreferences, it works fine with one Child, but once a second child is added it seems to be creating multiple Instances of SharedPreferences.
I have cut out everything to show what I am trying to achieve. NOTE this is being used as a Web App if it matters.
Oh and ChildModule needs to have its own state because it has a widget which requires it (not shown)
ENQUIRY FORM
final GlobalKey<FormBuilderState> _enquiryFormKey = GlobalKey<FormBuilderState>();
class EnquiryForm extends StatefulWidget {
static List<int> numberOfChildren = [1];
#override
_EnquiryFormState createState() => _EnquiryFormState();
}
class _EnquiryFormState extends State<EnquiryForm> {
int defaultNumberOfChildren = 1;
removeModule(){
setState(() {});
}
#override
Widget build(BuildContext context) {
return FormBuilder(
key: _enquiryFormKey,
child: Column(
children: <Widget>[
Row(
children: <Widget>[
Expanded(
child: CustomTextField(
label: 'Parent First Name',
isRequired: true,
),
),
),
//ChildModuleList
ListView.builder(
shrinkWrap: true,
itemCount: EnquiryForm.numberOfChildren.length,
itemBuilder: (context,int index){
return ChildModule(EnquiryForm.numberOfChildren[index], removeModule);
}
),
SizedBox(height: 20,),
Row(
mainAxisAlignment: MainAxisAlignment.end,
children: <Widget>[
ThemedButton(
onPressed: (){
setState(() {
defaultNumberOfChildren++;
EnquiryForm.numberOfChildren.add(defaultNumberOfChildren);
});
},
child: Text(
'Add Additional Child',
style: TextStyle(color: Colors.white),)
),
SizedBox(width: 10,),
ThemedButton(
onPressed: (){},
child: Text('Enquire Now', style: TextStyle(color: Colors.white),))
],
)
],
));
}
}
CHILD MODULE
class ChildModule extends StatefulWidget {
final int number;
final Function() callback;
ChildModule(this.number,this.callback);
#override
_ChildModule createState() => _ChildModule();
}
class _ChildModule extends State<ChildModule> {
SharedPreferences childModuleData;
String firstName;
bool loading = true;
bool isOpen;
#override
void initState() {
print('this module number is ${widget.number}');
_spInstance();
isOpen = true;
super.initState();
}
Future<void> _spInstance() async {
if(childModuleData == null && widget.number == 1) {
childModuleData = await SharedPreferences.getInstance();
print('got instance');
} else {
print('broken');
print(childModuleData);
};
String _testValue = childModuleData.getString('Child First Name');
if(_testValue == null){
childModuleData.setString('Child First Name', '');
loading = false;
} else {
childModuleData.clear();
_spInstance();
}
}
#override
Widget build(BuildContext context) {
return loading ? Loading() : Column(
children: <Widget>[
GestureDetector(
onTap: () {
setState(() {
if (isOpen == false) {
isOpen = true;
} else {
isOpen = false;
}
});
},
child: Container(
height: 40,
padding: EdgeInsets.only(left: 10, right: 10),
decoration: BoxDecoration(
borderRadius: BorderRadius.all(Radius.circular(4.0)),
color: Colors.blue[50],
),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
Text(
'Child Details',
style: TextStyle(color: Colors.blue[300], fontSize: 16),
),
Row(
children: <Widget>[
isOpen
? Icon(
Icons.arrow_drop_down,
size: 30,
)
: Transform.rotate(
angle: math.pi / 2,
child: Icon(
Icons.arrow_drop_down,
size: 30,
),
),
widget.number > 1
? IconButton(icon: Icon(Icons.clear), onPressed: () async {
await FormFunctions().removeModule(widget.number, EnquiryForm.numberOfChildren);
widget.callback();
})
: Container(),
],
),
],
),
),
),
AnimatedContainer(
duration: Duration(seconds: 2),
curve: Curves.fastOutSlowIn,
padding: EdgeInsets.fromLTRB(10, 5, 10, 5),
height: isOpen ? null : 0,
decoration: BoxDecoration(
border: Border.all(color: Colors.grey[300]),
borderRadius: BorderRadius.all(Radius.circular(4.0)),
),
child: Column(
children: <Widget>[
Row(
children: <Widget>[
CustomTextField(
label: fieldFirstName,
isRequired: true,
initalValue: childModuleData.getString(fieldFirstName) ?? '',
onChanged: (value){
childModuleData.setString(fieldFirstName, value);
},
),
],
),
],
),
),
],
);
}
}
CONSOLE ERROR AFTER SECOND MODULE IS CREATED
Launching lib/main.dart on Chrome in debug mode...
Syncing files to device Chrome...
Debug service listening on ws://127.0.0.1:58490/EkMAy9CGY74=
Debug service listening on ws://127.0.0.1:58490/EkMAy9CGY74=
this module number is 1
got instance
Instance of 'SharedPreferences'
null
this module number is 2 //Number 2 Module is created
broken
null
null
TypeError: Cannot read property 'getString' of null
at child_module._ChildModule.new._spInstance$ (http://localhost:58433/packages/webenrol/shared/widgets/day_button.dart.lib.js:3704:47)
at _spInstance$.next (<anonymous>)
at runBody (http://localhost:58433/dart_sdk.js:43121:34)
at Object._async [as async] (http://localhost:58433/dart_sdk.js:43149:7)
at child_module._ChildModule.new.[_spInstance] (http://localhost:58433/packages/webenrol/shared/widgets/day_button.dart.lib.js:3694:20)
at child_module._ChildModule.new.initState (http://localhost:58433/packages/webenrol/shared/widgets/day_button.dart.lib.js:3689:24)
at framework.StatefulElement.new.[_firstBuild] (http://localhost:58433/packages/flutter/src/widgets/widget_span.dart.lib.js:41219:58)
at framework.StatefulElement.new.mount (http://localhost:58433/packages/flutter/src/widgets/widget_span.dart.lib.js:12605:24)
at framework.SingleChildRenderObjectElement.new.inflateWidget (http://localhost:58433/packages/flutter/src/widgets/widget_span.dart.lib.js:11420:16)
in your case the concern is at the level of recording data in shared preferences. one solution would be to add the widget number in the key to save like this (await SharedPreferences.getInstance()).setString("Your Key${widgetNumber}");
and edit your function _spInstance
class ChildModule extends StatefulWidget {
final int number;
final Function() callback;
ChildModule(this.number,this.callback);
#override
_ChildModule createState() => _ChildModule();
}
class _ChildModule extends State<ChildModule> {
SharedPreferences childModuleData;
...
Future<void> _spInstance() async {
if(childModuleData == null) {
childModuleData = await SharedPreferences.getInstance();
print('got instance');
}
String _testValue = childModuleData.getString('Child First Name${widget.number}');
//NB: do not clear data on chlidModuleData any more.
...
}
...
}

Flutter : The onRefresh callback returned null

Sorry I'm new to flutter and trying to learn it. I have an issue with RefreshIndicator.
When I try pulling it I got an error like below :
════════ Exception caught by material library ══════════════════════════════════════════════════════
The following assertion was thrown when calling onRefresh:
The onRefresh callback returned null.
The RefreshIndicator onRefresh callback must return a Future.
════════════════════════════════════════════════════════════════════════════════════════════════════
Currently I am using flutter_bloc. Here is my sample code
TableList_bloc.dart
import 'dart:async';
import 'package:bloc/bloc.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';
import 'package:pos_project_bloc/modal/api.dart';
class ModalTableList {
final String Table_Number;
final String Name_Table;
ModalTableList(
this.Table_Number,
this.Name_Table,
);
}
class tablelistbloc extends Bloc<bool, List<ModalTableList>>{
#override
// TODO: implement initialState
List<ModalTableList> get initialState => [];
#override
Stream<List<ModalTableList>> mapEventToState(bool event) async* {
// TODO: implement mapEventToState
List<ModalTableList> tablelist =[];
try {
final response = await http.get(BaseUrl.GetTableList);
final data = jsonDecode(response.body);
if (data.length != 0) {
data.forEach((api) {
tablelist.add(
ModalTableList(
api['Table_Number'],
api['Name_Table'],
)
);
print("test"+api['Table_Number'].toString());
});
print("Get Table List : sukses");
} else {
print('data kosong');
}
} catch (e) {
print("Error GetTableList :");
print(e);
}
yield tablelist;
}
}
TabeList.dart
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:pos_project_bloc/bloc/TableList_bloc.dart';
import 'package:pos_project_bloc/modal/SharedPreferences.dart';
class TableList extends StatefulWidget {
#override
_TableListState createState() => _TableListState();
}
class _TableListState extends State<TableList> {
#override
void initState() {
super.initState();
BlocProvider.of<tablelistbloc>(context).add(true);
}
Widget build(BuildContext context) {
final GlobalKey<RefreshIndicatorState> refresh = GlobalKey<RefreshIndicatorState>();
Future<Null> _refresh() async{
BlocProvider.of<tablelistbloc>(context).add(true);
}
return Scaffold(
appBar: AppBar(
backgroundColor: Colors.lightBlueAccent,
title: new Center(
child: new Text('Available Table',
style: new TextStyle(color: Colors.white, fontSize: 15.0)),
)
),
floatingActionButton: Container(
child: Column(
mainAxisAlignment: MainAxisAlignment.end,
children: <Widget>[
Padding(
padding: EdgeInsets.all(5.0),
child: FloatingActionButton.extended(
heroTag: 1,
icon: Icon(Icons.refresh),
label: Text('Refresh Table List'),
onPressed: () {
BlocProvider.of<tablelistbloc>(context).add(true);
},
),
)
],
),
),
body: RefreshIndicator(
onRefresh: (){
_refresh();
},
key: refresh,
child: BlocBuilder<tablelistbloc,List<ModalTableList>>(
builder: (context,tablelist)=> ListView.builder(
itemCount: tablelist.length,
itemBuilder: (context,index){
final x = tablelist[index];
return GestureDetector(
onTap: (){
print("Selected Available Table On Tap : " + x.Table_Number);
Shared_Preferences().SaveTableNumber(
x.Table_Number
);
Navigator.pushReplacementNamed(context, '/POS');
},
child: Container(
decoration: BoxDecoration(
border: Border(
bottom: BorderSide(
width: 2.0,
color: Colors.grey.withOpacity(0.4),
))),
padding: EdgeInsets.all(10.0),
child: Row(
children: <Widget>[
Icon(
Icons.table_chart,
size: 100.0,
color: Colors.lightBlueAccent,
),
Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Text(
'Table Number : ' + x.Table_Number,
style: TextStyle(
fontSize: 20.0,
fontWeight: FontWeight.bold,
color: Colors.lightBlueAccent),
),
Text(
'Name : ' + x.Name_Table,
style: TextStyle(
fontSize: 20.0,
fontWeight: FontWeight.bold,
color: Colors.lightBlueAccent),
),
],
)
],
),
),
);
},
),
),
)
);
}
}
Just add async.
onRefresh: () async {
GetTableList.add(true);
},
onRefresh is a RefreshCallback, and RefreshCallback is a Future Function().
So if GetTableList.add(true) not return Future, must to add async.
it is says onRefresh callback must return a Future.
and it is seems like your are not returning Future from onRefresh
onRefresh: _refresh
Future<Null> _refresh() async{
GetTableList.add(true);
}
hope it helps..
You can problably use the following:
Future<bool> refresh() async {
//your refresh code
return true;
}

How to pass data back from a widget?

I have a screen where users can add a location. Here, I have separated all my widgets into there own files as illustrated below;
import 'package:cached_network_image/cached_network_image.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
import 'package:fluttershare/pages/location/location_help_screen.dart';
import 'package:fluttershare/widgets/common_widgets/customDivider.dart';
import 'package:uuid/uuid.dart';
import '../../widgets/camp_type_select.dart';
import '../../widgets/extra_location_notes.dart';
import '../../widgets/location_input.dart';
import '../../widgets/opening_times.dart';
import '../../widgets/post_media.dart';
import '../../widgets/space_avalibility.dart';
import '../../widgets/utility_type_select.dart';
import '../../widgets/width_restriction.dart';
import '../../widgets/height_restriction.dart';
import '../../models/locations.dart';
import '../../models/user.dart';
import '../home.dart';
class AddNewLocation extends StatefulWidget {
static const routeName = '/add-new-location';
final User currentUser;
AddNewLocation({this.currentUser});
_AddNewLocationState createState() => _AddNewLocationState();
}
class _AddNewLocationState extends State<AddNewLocation> {
String postId = Uuid().v4();
final _scaffoldKey = GlobalKey<ScaffoldState>();
PlaceLocation _pickedLocation;
int storyPostCount = 0;
bool isLoading = false;
void _selectPlace(double lat, double lng) {
_pickedLocation = PlaceLocation(lattitude: lat, longitude: lng);
}
getLocationPostCount() async {
setState(() {
isLoading = true;
});
QuerySnapshot snapshot = await locationPostRef
.document(currentUser.id)
.collection('user_location_posts')
.getDocuments();
setState(() {
storyPostCount = snapshot.documents.length;
});
}
createLocationPostInFirestore(
{String mediaUrl,
String description,
double heightRestriction,
double widthRestriction}) {
locationPostRef
.document(currentUser.id)
.collection("user_location_posts")
.document(postId)
.setData({
"postId": postId,
"ownerId": currentUser.id,
"username": currentUser.username,
"description": description,
"timestamp": timestamp,
"lattitude": _pickedLocation.lattitude,
"longitude": _pickedLocation.longitude,
"max_height": heightRestrictionValue.toStringAsFixed(0),
"max_width": widthRestrictionValue.toStringAsFixed(0),
});
}
handlePostSubmit() {
createLocationPostInFirestore(
heightRestriction: heightRestrictionValue,
widthRestriction: widthRestrictionValue,
);
SnackBar snackbar = SnackBar(
content: Text("Profile Updated"),
);
_scaffoldKey.currentState.showSnackBar(snackbar);
setState(() {
postId = Uuid().v4();
});
}
buildUploadUserHeader() {
return Container(
margin: EdgeInsets.only(bottom: 10),
height: 200,
child: Row(
children: <Widget>[
Expanded(
flex: 2,
child: Container(
color: Colors.blue,
child: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
ListTile(
leading: CircleAvatar(
backgroundImage:
CachedNetworkImageProvider(currentUser.photoUrl)),
),
],
),
),
),
Expanded(
flex: 6,
child: Container(
color: Colors.pink,
child: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
mainAxisSize: MainAxisSize.max,
children: <Widget>[
Text(currentUser.displayName),
],
),
),
),
],
),
);
}
buildCampUploadForm() {
return Container(
child: SingleChildScrollView(
child: Column(
children: <Widget>[
//buildUploadUserHeader(), //TODO: This is the profile header that is dissabled for now. Work on possibly a header in the future.
Container(
padding: EdgeInsets.all(15),
child: Column(
children: <Widget>[
CampTypeSelect(),
CustomDivider(),
LocationInput(_selectPlace),
CustomDivider(),
HeightRestriction(),
WidthRestriction(),
SpaceAvalibility(),
OpeningTimes(),
CustomDivider(),
PostMedia(),
CustomDivider(),
UtilityServices(),
CustomDivider(),
ExtraLocationNotes(),
Container(
height: 80,
margin: EdgeInsets.only(top: 10, bottom: 10),
child: Row(
children: <Widget>[
Expanded(
child: FlatButton(
color: Colors.black,
onPressed: () => handlePostSubmit(),
child: Text(
"SUBMIT",
style: Theme.of(context).textTheme.display2,
),
padding: EdgeInsets.all(20),
),
)
],
),
),
],
),
),
],
),
));
}
#override
Widget build(BuildContext context) {
return Scaffold(
key: _scaffoldKey,
appBar: AppBar(
automaticallyImplyLeading: false,
title: const Text(
'Add New Location',
style: TextStyle(color: Colors.black),
),
actions: <Widget>[
// action button
IconButton(
icon: Icon(Icons.info_outline),
color: Colors.black,
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(
fullscreenDialog: true,
builder: (context) => LocationSubmitHelpScreen()),
);
},
),
// action button
IconButton(
icon: Icon(Icons.close),
color: Colors.black,
onPressed: () {
Navigator.of(context).pop();
},
),
],
),
body: buildCampUploadForm(),
backgroundColor: Colors.white,
);
}
}
What I am trying to do is pass the data back from the widget ExtraLocationNotes()
to the function createLocationPostInFirestore().
For context, this is what my widget looks like;
import 'package:flutter/material.dart';
import 'common_widgets/custom_form_card.dart';
class ExtraLocationNotes extends StatefulWidget {
_ExtraLocationNotesState createState() => _ExtraLocationNotesState();
}
class _ExtraLocationNotesState extends State<ExtraLocationNotes> {
TextEditingController descriptionController = TextEditingController();
#override
Widget build(BuildContext context) {
return CustomFormCard(
child: Column(
children: <Widget>[
Container(
child: Row(
children: <Widget>[
Text(
"EXTRA INFORMATION",
style: TextStyle(
fontSize: 18.0,
color: Colors.black,
fontWeight: FontWeight.w400,
letterSpacing: 2.0,
),
),
],
),
),
SizedBox(height: 20),
TextFormField(
controller: descriptionController,
maxLines: 6,
maxLength: 250,
maxLengthEnforced: true,
style:
new TextStyle(fontSize: 18.0, height: 1.3, color: Colors.black),
decoration: const InputDecoration(
hintText:
"Please write a description of this location for fellow travellers.",
alignLabelWithHint: true,
border: OutlineInputBorder(
borderRadius: BorderRadius.only(),
borderSide: BorderSide(color: Colors.black),
),
),
),
],
),
);
}
}
How do I pass the data back to the parent widget?
You need a callback, which will be triggered in the child widget then the value will be updated in the parent widget:
// 1- Define a pointers to executable code in memory, which is the callback.
typedef void MyCallback(String val);
class ExtraLocationNotes extends StatefulWidget {
// 2- You will pass it to this widget with the constructor.
final MyCallback cb;
// 3- ..pass it to this widget with the constructor
ExtraLocationNotes({this.cb});
_ExtraLocationNotesState createState() => _ExtraLocationNotesState();
}
class _ExtraLocationNotesState extends State<ExtraLocationNotes> {
//..
//...
RaisedButton(
//..
// 4- in any event inside the child you can call the callback with
// the data you want to send back to the parent widget:
onPressed: () {
widget.cb("Hello from the other side!");
}
),
}
Then inside the parent widget you need to catch the data which sent form the child:
class AddNewLocation extends StatefulWidget {
//...
_AddNewLocationState createState() => _AddNewLocationState();
}
class _AddNewLocationState extends State<AddNewLocation> {
// 1- Global var to store the data that we're waiting for.
String _dataFromMyChild = "";
buildCampUploadForm() {
return Container(
//...
//...
// 2- Pass the callback with the constructor of the child, this
// will update _dataFromMyChild's value:
ExtraLocationNotes(cb: (v) => setState(() => _dataFromMyChild = v)),
//..
}
// then
createLocationPostInFirestore() {
// Use _dataFromMyChild's value here
}
}
You can use the BuildContext object to get the context widget (might no be the parent!) couldn't read it all but as i understand that you need to pass the info from the child to the parent ,and you can do it with some like this :-
(context.widget as MyType).doStuff();
Note.
please check first with
print(context.widget.runtimeType);
but to make a better solution make a mutable data object that is passed from parent to the child so when changes happens it reflect's on the parent so you can separate business logic from ui logic.