i have two future methods
Future<List> getTrns(String token,int page,) async {
final response = await
http.get(Uri.parse("api1/?params" ),
headers:{
....
});
final String t = response.body;
List list =jsonDecode(t)['data'];
return list;
}
Future<String> getstate(String code,String token,DateTime now) async {
DateTime start_date = new DateTime(now.year, now.month, now.day);
String stat='';
final response = await
http.get(Uri.parse("api2/?params" ),
headers:{
...
});
final String t = response.body;
List l = jsonDecode(t)['data'];
if(l.length == 0){
stat = "absent";
}else {
stat = "present";
}
return stat;
}
this first methode will get the list of employee while the second one will use each employee code to find their state from another api.. the two functions are working fine but displaying them in an Datatable gave me an error of
Instance of future<string>
Only in the stat cell while other cells are working fine
here's how i built the table
body: Column( children: <Widget>[
FutureBuilder<List>(
future: getTrns(widget.token,widget.page),
builder: (ctx,ss){
if(ss.hasError){
print("error");
}
if(ss.hasData){
datalist=ss.data!;
return SingleChildScrollView(
scrollDirection: Axis.horizontal,
child: SingleChildScrollView(
scrollDirection: Axis.vertical,
child: _createDataTable(),
)
);
}else {
return Center(child: CircularProgressIndicator());
}
}
),
MaterialButton(onPressed: () {
widget.page = widget.page+1;
print(widget.page);
},
child: Text("Next"),
color: Colors.blue,)
]
)
)
);
}
DataTable _createDataTable() {
return DataTable(columns: _createColumns(), rows: _createRows());
}
List<DataColumn> _createColumns() {
return [
DataColumn(label: Text('ID')),
DataColumn(label: Text('Full Name')),
DataColumn(label: Text('State'))
];
}
List<DataRow> _createRows() {
return datalist
.map((list) => DataRow(cells: [
DataCell(
Text(list['emp_code'].toString()),
onTap: (){
Navigator.of(context).push(
MaterialPageRoute(builder: (BuildContext context)=>Details(token: w idget.token, emp:list['emp_code'].toString())
));
}
),
DataCell(
Text(list['first_name'].toString()+" "+list['last_name'].toString()),
onTap: (){
Navigator.of(context).push(
MaterialPageRoute(builder: (BuildContext context)=>Details(token: widget.token, emp:list['emp_code'].toString())
));
}
),
DataCell(Text( getstate(list['emp_code'], widget.token, widget.now).toString() ),
onTap: (){
Navigator.of(context).push(
MaterialPageRoute(builder: (BuildContext context)=>Details(token: widget.token, emp:list['emp_code'].toString())
));
}
)
]))
.toList();
}
}
this is the result
table screenshot
Edit1: new cell code cell code
the error is random, sometimes in first celland sometimes in a different one
first result
another result
You will need another FutureBuilder around getstate just as you did with getTrns.
Your code already demonstrates that you know how to use one, so I will not bore you with it.
If you need a refresher: What is a Future and how do I use it?
You may want to put your Future, into a variable instead of directly refering to them in your FutureBuilders though, because you want to keep the same Future (or rather it's probably already existing result) when the user trigger a rebuild that has nothing to do with your data, for example by tilting the screen of their device or changing the size of their browser or desktop window.
Try this
final Map<String, dynamic> t = response.body;
list =jsonDecode(t)['data'] as Map<String, dynamic>;
return list;
Related
guys
I'm trying to Create a list to add and delete items which are already stored in my database(MongoDB). I already created an Animated list that once its clicked on it deletes the item but as soon as i add the function to remove the item from the database it begins to show a loader as I used a ListView.builder
FutureBuilder(
builder: (context, projectSnap) {
if (projectSnap.connectionState == ConnectionState.none &&
projectSnap.hasData == null) {
//print('project snapshot data is: ${projectSnap.data}');
return Text('Nothing To show Here');
}else if(
projectSnap.connectionState == ConnectionState.waiting
) {
return Center(child: CircularProgressIndicator());
} else if(
projectSnap.connectionState == ConnectionState.active
) {
return AnimatedList(
padding: EdgeInsets.zero,
key: _listKey,
physics: NeverScrollableScrollPhysics(),
shrinkWrap: true,
initialItemCount: pairlenght,
itemBuilder: (BuildContext context, int index, animation) {
pair1 = pair[index].split(" ")[1];
pair0 = pair[index].split(" ")[0];
return _buildItem(pair, index, animation);
}
);
}
else{
return AnimatedList(
padding: EdgeInsets.zero,
key: _listKey,
physics: NeverScrollableScrollPhysics(),
shrinkWrap: true,
initialItemCount: pairlenght,
itemBuilder: (BuildContext context, int index, animation) {
pair1 = pair[index].split(" ")[1];
pair0 = pair[index].split(" ")[0];
return _buildItem(pair, index, animation);
}
);
}
},
future: fetchlist(),
),
This is the code for the list
void _removeSingleItems(int index) {
int removeIndex = index;
String removedItem = pair.removeAt(removeIndex);
// This builder is just so that the animation has something
// to work with before it disappears from view since the original
// has already been deleted.
AnimatedListRemovedItemBuilder builder = (context, animation) {
// A method to build the Card widget.
return _buildItem(removedItem, index, animation);
};
_listKey.currentState?.removeItem(removeIndex, builder);
}
This is the code to delete the item using Animated list
This is the how it works
So what I actually need is just a better alternative if listview.builder won't do the job.
Cause whenever I delete it loads again which I don't want
so, I am using a search Delegate to allow user search, however, when user is inputting data, it's really slow, it lags and skips frames as they type, because my search delegate loops through a list that contains about 2000 objects and checks user query against each object's title and main text, making about 4000 search criteria in total, this was causing the lag, so to solve this, I simply spawned a new isolate to handle the suggestions building, as such
Future<List<Data>> allData(String query) async {
List<Data> suggestions;
List<Data> myData(String message) {
return allData.where((data) {
final result = data.dataText.replaceAll(RegExp('[^A-Za-z0-9 ]'), '').toLowerCase();
final result1 = data.dataText.replaceAll(RegExp('[^A-Za-z0-9]'), '').toLowerCase();
final result2 = data.dataText.toLowerCase();
final result3 = data.dataText.replaceAll("th'incarnate", "the incarnate").toLowerCase();
final input = query.toLowerCase();
final result4 = data.dataTitle.toLowerCase();
final result5 = data.dataTitle.replaceAll(RegExp('[^A-Za-z0-9 ]'), '').toLowerCase();
final result6 =data.dataTitle.replaceAll(RegExp('[^A-Za-z0-9]'), '').toLowerCase();
return result.contains(input) ||
result1.contains(input) ||
result2.contains(input) ||
result3.contains(input) ||
result4.contains(input) ||
result5.contains(input) ||
result6.contains(input);
}).toList();
}
query.isEmpty
? suggestions = []
: suggestions = await compute<String, List<Data>>(
myData,
"",
);
if (query.isNotEmpty && suggestions.isEmpty) {
return [
Data(
DataTitle: "No Results",
DataText: "No Results",
),
];
} else {
return suggestions;
}
}
then in buildSuggestions I did this
#override
Widget buildSuggestions(BuildContext context) {
return FutureBuilder<List<Data>>(
future: DataBrain().allData(query),
builder: (context, snapshot) {
List<Data> suggestions;
query.isEmpty ? suggestions = [] : suggestions = snapshot.data!;
return ListView.builder(
itemCount: suggestions.length,
itemBuilder: (context, suggestIndex) {
final suggestion = suggestions[suggestIndex];
if (snapshot.connectionState == ConnectionState.done) {
if (suggestion.dataText.toLowerCase() == "no results") {
return const ListTile(
title: Text("No results"),
subtitle: Text("Please check for spelling mistakes"),
);
} else {
return ListTile(
title: Text(suggestion.dataTitle),
trailing: Text(
'${suggestion.dataBookName} ${suggestion.dataBookNumber == 0 ? '30a' : suggestion.dataBookNumber}',
style: const TextStyle(
fontStyle: FontStyle.italic,
fontWeight: FontWeight.w300,
),
),
onTap: () {
close(context, suggestion);
},
);
}
} else {
return const ListTile(
title: Text('Loading...'),
);
}
});
});
}
it works fine without lags, however now, the suggestions don't build as user types, it waits till user is no longer typing, for like 2 seconds, then it builds suggestions, I think this is because it's a future and in a future builder, I'm not sure why. I'm thinking of turning it into a stream rather and listen to query change and build immediately instead of awaiting for two seconds after user stops querying, is there any workaround, what's a good way to eliminate the delay, i need it to filter the list and build suggestions with each keystroke, as it used to do before i moved it to a new isolate and made it a future
i've been working with wallpaper app.
i manage to call the path list for wallpaper,
i can make this work on image card list but i can't manage to do it work with assetPath for WallpaperManager
Please help, is there any way to do it?
Future<void> setWallpaperFromAsset() async {
setState(() {
_wallpaperAsset = "Loading";
});
String result;
String assetPath = ('Load List here');
You can add a parameter assetPath to setWallpaperFromAsset
Future<void> setWallpaperFromAsset(String assetPath) async {
setState(() {
_wallpaperAsset = "Loading";
});
String result;
// Platform messages may fail, so we use a try/catch PlatformException.
try {
result = await WallpaperManager.setWallpaperFromAsset(
assetPath, WallpaperManager.HOME_SCREEN);
} on PlatformException {
result = 'Failed to get wallpaper.';
}
}
And you register the onPressed callback with:
RaisedButton.icon(
onPressed: () => setWallpaperFromAsset(item),
icon: Icon (Icons.wallpaper, size: 20),
label: Text('homescreen')),
)
I know how to get the device unique id in flutter, but when I add it as a parameter to url and call it with webview, I can't get the result I want. When I call the following function, webview is loaded with empty device id parameter because it is working ASYNC and not yet completed and not returning any value.
Future<String> _getId() async {
DeviceInfoPlugin deviceInfo = DeviceInfoPlugin();
if (Theme.of(context).platform == TargetPlatform.iOS) {
IosDeviceInfo iosDeviceInfo = await deviceInfo.iosInfo;
return iosDeviceInfo.identifierForVendor; // unique ID on iOS
} else {
AndroidDeviceInfo androidDeviceInfo = await deviceInfo.androidInfo;
return androidDeviceInfo.androidId; // unique ID on Android
}
}
The webview loading function is below;
String webViewUrl;
_getId().then((id) {
webViewUrl = "http://websiteblabla.com/?deviceid="+id;
return WebviewScaffold(
url: webViewUrl,
withJavascript: true,
withZoom: false
);
}
How can I get URL with unique Android or iOS device id in webview when it is ready?
You can create Future function or method which will return WebviewScaffold widget when everything is ready. And the use it with FutureBuilder. It would look something like this.
FutureBuilder(
future: _buildWebview(),
builder: (context, snapshot) {
if(!snapshot.hasData) return Center(
child: CircularProgressIndicator(),
);
return snapshot.data;
},
),
Future<Widget> _buildWebview() async {
await _getId().then((id) {
webViewUrl = "http://websiteblabla.com/?deviceid="+id;
return WebviewScaffold(
url: webViewUrl,
withJavascript: true,
withZoom: false
);
}
}
I write an app in flutter. I want to change the state of a string variable. After I set the state of the string variable, the ModalRoute PopUpMenu does not show the changed variable. If I close the ModalRoute PopUpMenu and open it again, I can see the changed variable.
I tried to pop the context, but I want the change on the PopUpMenu. I've got my own Overlay widget.
class MyOverlay extends ModalRoute {
...
}
// this is my main.dart:
List<String> categories = ['please', 'help', 'me'];
String _selectedCategory = 'category';
// this is where the PopUpMenu starts
floatingActionButton: FloatingActionButton(
child: ...,
onPressed: () {
_showPopup(context, _popupBody(), 'Add');
},
),
_showPopup(BuildContext context, Widget widget, String title, {BuildContext popupContext}) {
Navigator.push(
context,
MyOverlay(
...
onPressed: () {
try {
Navigator.pop(context); //close the popup
} catch (e) {
print(e);
}
},
...
body: widget,
) ...
);
}
Widget _popupBody() {
...
PopupMenuButton<String>(
// HERE IS THE PROBLEM THIS SHOULD CHANGE WHEN I SELECT
child: Text('$_selectedCategory'),
itemBuilder: (BuildContext context) {
return categories.map((String choice) {
return PopupMenuItem<String>(
value: choice,
child: Text(choice),
);
}).toList();
},
onSelected: _selectCategory,
),
...
}
void _selectCategory(String category) {
setState(() => this._selectedCategory = category);
}
The text widget does not change if I select the PopupMenuItem.
I have the same problem, I fixed for the moment using changedExternalState (); to force a rebuild, but i think maybe this isn't optimal.
Example:
CheckboxListTile(
value: _checkboxValue,
title: Text(phone),
onChanged: (value){
_checkboxValue = value;
//Fix
changedExternalState();
},
)