How can I implement search in this Flutter app - search

Question

I'm trying to add a search feature to this flutter app since the json file it pulls data from has 7000 results.
Mainly I'm trying to do search for "ctry" and "peopnameincountry". This was ripped from https://www.youtube.com/watch?v=EwHMSxSWIvQ
As is .. it works fine in fetching the json list and the tap to show detail page works as well.
I just need to implement the search on the main page so I don't have to scroll through the thousands of results.
Appreciate any help .. thank you all.
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'dart:async';
import 'package:http/http.dart' as http;
import 'dart:convert';
void main() => runApp(new UnReached());
class UnReached extends StatelessWidget {
#override
Widget build(BuildContext context) {
return new MaterialApp(
title: 'Flutter Demo',
theme: new ThemeData(
primarySwatch: Colors.blue,
),
home: new MyHomePage(title: 'Unreached'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => new _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
Future<List<User>> _getUsers() async {
var data = await http.get("https://cmfiflutterapp.s3-ap-southeast-2.amazonaws.com/UnreachedPeoplesGroup.json");
var jsonData = json.decode(data.body);
List<User> users = [];
for(var u in jsonData){
User user = User(u["ctry"], u["peopnameincountry"], u["population"], u["primarylanguagename"], u["biblestatus"], u["primaryreligion"], u["continent"]);
users.add(user);
}
print(users.length);
return users;
}
#override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: Text(widget.title),
),
body: Container(
child: FutureBuilder(
future: _getUsers(),
builder: (BuildContext context, AsyncSnapshot snapshot){
print(snapshot.data);
if(snapshot.data == null){
return Container(
child: Center(
child: Text("Loading...")
)
);
} else {
return ListView.builder(
itemCount: snapshot.data.length,
itemBuilder: (BuildContext context, int index) {
return ListTile(
leading: Icon(Icons.arrow_forward_ios),
// leading: CircleAvatar(
// backgroundImage: NetworkImage(
// snapshot.data[index].picture
// ),
// ),
title: Text(snapshot.data[index].peopnameincountry),
subtitle: Text(snapshot.data[index].ctry),
onTap: (){
Navigator.push(context,
new MaterialPageRoute(builder: (context) => DetailPage(snapshot.data[index]))
);
},
);
},
);
}
},
),
),
);
}
}

Answer 1

Try adding these function in your code:
import 'package:flutter/material.dart';
import 'dart:core';
class HomeScreen1 extends StatefulWidget {
#override
HomeScreenState createState() => HomeScreenState();
}
class HomeScreenState extends State<HomeScreen1> {
var searchController = new TextEditingController();
String search;
List<String> _filterList;
String _query = "";
bool _firstSearch = true;
#override
void initState() {
super.initState();
}
HomeScreenState() {
searchController.addListener(() {
if (searchController.text.isEmpty) {
setState(() {
_firstSearch = true;
_query = "";
});
} else {
setState(() {
_firstSearch = false;
_query = searchController.text;
});
}
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: new Container(
margin: EdgeInsets.only(left: 10.0, right: 10.0, top: 10.0),
child: new Column(
children: <Widget>[
_createSearchView(),
new Expanded(
child: _firstSearch ? _createListView() : _performSearch(),
),
],
),
),
);
}
Widget _createSearchView() {
return new Container(
decoration: BoxDecoration(border: Border.all(width: 1.0)),
child: new TextField(
controller: searchController,
decoration: InputDecoration(
icon: Icon(Icons.search),
hintText: "Search",
hintStyle: new TextStyle(color: Colors.grey[300]),
),
//textAlign: TextAlign.center,
),
);
}
Widget _createListView() {
return FutureBuilder(
future: _getUsers(),
builder: (BuildContext context, AsyncSnapshot snapshot){
print(snapshot.data);
if(snapshot.data == null){
return Container(
child: Center(
child: Text("Loading...")
)
);
} else {
return ListView.builder(
itemCount: snapshot.data.length,
itemBuilder: (BuildContext context, int index) {
return ListTile(
leading: Icon(Icons.arrow_forward_ios),
// leading: CircleAvatar(
// backgroundImage: NetworkImage(
// snapshot.data[index].picture
// ),
// ),
title: Text(snapshot.data[index].peopnameincountry),
subtitle: Text(snapshot.data[index].ctry),
onTap: (){
Navigator.push(context,
new MaterialPageRoute(builder: (context) => DetailPage(snapshot.data[index]))
);
},
);
},
);
}
},
),
}
Widget _performSearch() {
return FutureBuilder<List>(builder: (context, snapshot) {
_filterList = new List<String>();
for (int i = 0; i < snapshot.data.length; i++) {
var item = snapshot.data[i];
if ((item.toString().toLowerCase()).contains(_query.toLowerCase())) {
_filterList.add(item.toString());
}
}
return _createFilteredListView();
});
}
Widget _createFilteredListView() {
return ListView.builder(
itemCount: _filterList.length,
itemBuilder: (BuildContext context, int index) {
return new Card(
color: Colors.white,
elevation: 5.0,
child: new Container(
margin: EdgeInsets.all(15.0),
child: new Text("${_filterList[index]}"),
),
);
});
}
}

Answer 2

The concept of a FutureBuilder widget is to be build as soon as it is received, but meanwhile, the snapshot contains no data at all. So when you're calling :
for (int i = 0; i < snapshot.data.length; i++) {
you're, at least at first, calling length on null since the data is not yet received.
The solution is to create a switch and call `snapshot.data when the status is completed:
switch (snapshot.connectionState) {
case ConnectionState.none:
return DefaultWidget(); // For instance a CircularProgress
case ConnectionState.active:
return DefaultWidget(); // For instance a CircularProgress
case ConnectionState.waiting:
return DefaultWidget(); // For instance a CircularProgress
case ConnectionState.done:
if (snapshot.hasError)
return ErrorWidget('Error: ${snapshot.error}'); //For example a Text Widget
// Your code here:
_filterList = new List<String>();
for (int i = 0; i < snapshot.data.length; i++) {
var item = snapshot.data[i];
if ((item.toString().toLowerCase()).contains(_query.toLowerCase())) {
_filterList.add(item.toString());
}
}
return _createFilteredListView();
}
return null; // unreachable
More on this here

Answer 3

My apologies guys...I ended up taking a slightly different approach which I thought was slightly faster in response than the FutureBuilder approach. Maybe it's just my internet. Not sure.
import 'package:flutter/material.dart';
import 'dart:core';
import 'package:http/http.dart' as http;
import 'dart:convert';
import 'dart:async';
import 'package:progress_indicators/progress_indicators.dart';
class IslandWaves extends StatefulWidget {
#override
HomeScreenState createState() => HomeScreenState();
}
class HomeScreenState extends State<IslandWaves> {
List<User> _list = [];
List<User> _search = [];
var loading = false;
Future<Null> fetchData() async {
setState(() {
loading = true;
});
_list.clear();
final response = await http.get(
"https://cmfiflutterapp.s3-ap-southeast-2.amazonaws.com/UnreachedPeoplesGroup.json");
if (response.statusCode == 200) {
final data = jsonDecode(response.body);
setState(() {
for (Map i in data) {
_list.add(User.formJson(i));
loading = false;
}
});
}
}
TextEditingController controller = new TextEditingController();
onSearch(String text) async {
_search.clear();
if (text.isEmpty) {
setState(() {});
return;
}
_list.forEach((f) {
if (f.ctry.contains(text) ||
f.peopnameincountry.toString().contains(text)) _search.add(f);
});
setState(() {});
}
#override
void initState() {
// TODO: implement initState
super.initState();
fetchData();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(),
body: Container(
child: Column(
children: <Widget>[
Container(
padding: EdgeInsets.all(10.0),
color: Colors.blue,
child: Card(
child: ListTile(
leading: Icon(Icons.search),
title: TextField(
controller: controller,
onChanged: onSearch,
decoration: InputDecoration(
hintText: "Search", border: InputBorder.none),
),
trailing: IconButton(
onPressed: () {
controller.clear();
onSearch('');
},
icon: Icon(Icons.cancel),
),
),
),
),
loading
? Center(
heightFactor: 20.0,
child: FadingText('Loading...'),
)
: Expanded(
child: _search.length != 0 || controller.text.isNotEmpty
? ListView.builder(
itemCount: _search.length,
itemBuilder: (context, i) {
final b = _search[i];
return GestureDetector(
onTap: () {
Navigator.push(
context,
new MaterialPageRoute(
builder: (context) =>
DetailPage(_search[i])));
debugPrint('TopNav');
},
child: Container(
padding: EdgeInsets.all(10.0),
child: Column(
crossAxisAlignment:
CrossAxisAlignment.start,
children: <Widget>[
Text(
b.ctry,
style: TextStyle(
fontWeight: FontWeight.bold,
fontSize: 18.0),
),
SizedBox(
height: 4.0,
),
Text(b.peopnameincountry),
],
)),
);
},
)
: ListView.builder(
itemCount: _list.length,
itemBuilder: (context, i) {
final a = _list[i];
return GestureDetector(
onTap: () {
Navigator.push(
context,
new MaterialPageRoute(
builder: (context) =>
DetailPage(_list[i])));
debugPrint('BottomNav');
},
child: Container(
padding: EdgeInsets.all(10.0),
child: Column(
crossAxisAlignment:
CrossAxisAlignment.start,
children: <Widget>[
Text(
a.ctry,
style: TextStyle(
fontWeight: FontWeight.bold,
fontSize: 18.0),
),
SizedBox(
height: 4.0,
),
Text(a.peopnameincountry),
],
)
),
);
},
),
),
],
),
),
);
}
}
class DetailPage extends StatelessWidget{....etc.}