How can I add circular progress indicator by the time I press the Elevated Button while I am waiting for my data to show? It would be possible without the need of implementing Future Builder?
ElevatedButton(
onPressed: (() async {
await postML(
_mySelectionFeat1,
_mySelectionFeat2,
_mySelectionFeat3,
_mySelectionValue1,
_mySelectionValue2,
_mySelectionValue3);
}),
child: Text('Post')),
ShowDogCard == false
? const Center(
child: Text('Please select features and values'),
)
: Container(
child: ListCard(
screen: 'ML',
doglist: BreedList,
index: idxBreedListPredicted,
),
),
A way is to have a boolean variable what you set true when you wanna start showing the CircularProgressIndicator, and then set false when you don't want to show it anymore:
bool _loading = true;
build() {
return _loading ? CircularProgressIndicator() : mainWidget();
}
But the best way is to use FutureBuilder. That's what it is for.
Related
I'm trying to create a "favorites" function using shared_preferences in flutter.
Use this method to store locally without a database.
The page to use is globals.dart with bool variable, button.dart which is the page selection window (change button color when bookmarked),
And there is a file home0_01.dart with a "favorite icon button (click to add that button to favorites)".
Here I would like to implement it to be stored locally using shared_prefer
But even looking at a lot of example code, it's hard to implement.
There are hundreds of favoriteButton_0_01 in my code because there are so many home0_01.dart files. How should I code in this case?
globals.dart
library prj.com.globals;
bool favoriteButton_0_01 = true;
bool favoriteButton_0_02 = false;
...
button.dart
...
LearnLevelButton(
color: favoriteButton_0_01 ? Colors.orange : Color(0xff7ba6f9),
text: '',
onTap: () async {
await Navigator.pushReplacement(context, MaterialPageRoute(builder: (context){
return home0_01();
}));
},
),
...
home0_01.dart
void delete() async {
setState(() {
favoriteButton_0_01 = false;
print(favoriteButton_0_01);
});
}
void saved() async {
setState(() {
favoriteButton_0_01 = true;
print(favoriteButton_0_01);
});
}
...
actions: <Widget>[
IconButton(
onPressed: favoriteButton_0_01 ? delete : saved,
icon: favoriteButton_0_01
? Icon(Icons.bookmark_rounded, color: Colors.yellow[800], size: 30)
: Icon(Icons.bookmark_add_outlined, color: Colors.yellow[800],size: 30),
),
],
...
You can watch this tutorial in order to accomplish something like that: https://www.youtube.com/watch?v=TRB0qZ2XaO4. It's basically the same idea. Press a button and add it somewhere else. Hope this might help.
I work on flutter project . when i click to modify icon to edit name for example ==> the screen is roaleded automatically . How i can stop refresh screen after click on edit button ?
this piece of my Form code :
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
Text('Adresse email :',
style: TextStyle(
color: Color(0xFF4053FCF),
fontSize: 16,
fontWeight: FontWeight.w600
),
),
IconButton(
icon: Icon(CommunityMaterialIcons.pencil,
color: Colors.grey,
),
onPressed: () {
emailNode.requestFocus();
setState(() {
enableemail = true;
});
})
],
),
void editUserProfile() async {
setState(() {});
// if (_formKey.currentState.validate()) {
String name = _nameController.text;
String email = _emailController.text;
String adress = _adressController.text;
userApi.editUserProfile(name, email, adress).then((data) {
print(data);
if (data != null) {
// Navigator.pop(context);
/* Navigator.push(
context, MaterialPageRoute(builder: (context) => Profile()));*/
}
// setState(() {});
/* Navigator.push(
context, MaterialPageRoute(builder: (context) => BoxSettings()));*/
setState(() {
enableup = false;
enableadress = false;
enableemail = false;
});
ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text(data)));
// ScaffoldMessenger.of(context).showSnackBar(snackBar3);
}).catchError((error) {
ScaffoldMessenger.of(context)
.showSnackBar(SnackBar(content: Text(error.toString())));
});
setState(() {});
}
and this my screen for more information :
How i can press on edit button without reload screen ?
There some workarounds to achieve this (i.e. update the state of one widget after tapping a completely different widget) like passing the callback function as a parameter etc.
But The best and neat solution here which will solve the above problem and keep your code neat is using Provider pattern.
If you are not aware of how a Provider pattern works, you can easily google search for articles regarding it. Here is one of them :
https://www.raywenderlich.com/6373413-state-management-with-provider
Read the above article before moving below.
Basically what we do is :
Create a ChangeNotifier class.
Wrap the parent of both widgets by a ChangeNotifierProvider widget.
Wrap the widget you want to update with Consumer widget.
Then in your onTap/onPressed function of Edit button you can call a function which will call the notifyListener() function. What this will do is it will notify the above ChangeNotifierProvider widget that some change has neen occured in it's widget tree. Then it will traverse the child whole widget tree below and will update the widget wrapped with Consumer widget.
So this way, you wont need to refresh your whole screen and you can easily update one widget by doing some action on a competely different widget.
Wrap the widgets you want to refresh inside stateful builder and make the whole screen a stateless widget and then call stateful builder
I am writing a flutter application and in it, I have join/leave event buttons when the stream comes in it sets the button to either true or false, eg: if a user is in the event it is set to true so the leave button shows up but when I click the leave button I have to click it twice to change before it changes back to the join button when I print the value i can see it change back to true the first click but the UI doesn't change the button back until the second click does anyone know why this is
child: eventStatus
? FlatButton(
child: Text('Leave Event'),
color: Colors.redAccent,
onPressed: () async {
int st = int.parse(eventData.votes);
int newVotes = --st;
await DatabaseService.instance.removeVote(
AuthService.instance.user.uid,
newVotes.toString(),
this.widget.event);
_snackbar.showSnackBarSuccess('OK LEAVE THEN !');
setState(() {
eventStatus = !eventStatus;
print(eventStatus);
});
})
: FlatButton(
child: Text('Join event'),
color: Colors.greenAccent,
onPressed: () async {
int st = int.parse(eventData.votes);
int newVotes = ++st;
await DatabaseService.instance
.vote(newVotes.toString(), this.widget.event);
_snackbar.showSnackBarSuccess('Hey you have friends !');
setState(() {
eventStatus = !eventStatus;
print(eventStatus);
});
}),
Use async/await in other function with Future, and call it in onPressed
So I have a login button that would initiate an async function logMeIn() for logging in, which returns a Future<bool> indicating if logging in was successful.
What I want to achieve is after pressing the button, the text within the button would change into a CircularProgressIndicator, and become plain text when logMeIn() has finished.
I know that I could use a FutureBuilder for one-time async tasks, but I simply can't think of a way to use it here.
How am I supposed to achieve this?
Thanks in advance.
Edit
I didn't provide more information because I'm pretty sure it wasn't how it's supposed to be done. But I'd share what I tried whatsoever.
My original button looks somewhat like this:
RaisedButton(
child: Text("Login")
)
I have a async login function that returns a Future<bool> which indicates if the login is successful or not.
Future<bool> logMeIn() async {
// login tasks here
}
What I want to do is to change the button to the following and run logMeIn() when I press the button, and change it back to the plain text version after it's finished:
RaisedButton(
child: CircularProgressIndicator()
onPressed: () {}
)
What I tried
I tried adding a logging_in boolean as a flag to control it, here I call the button with plain text StaticButton(), the other named ActiveButton:
Then I wrapped the ActiveButton with a FutureBuilder:
logging_in ? FutureBuilder(
future: logMeIn(),
builder: (_, snapshot) {
if(snapshot.hasData)
setState(() {
logging_in = false;
});
else
return ActiveButton();
}
) : StaticButton();
and when I pressed the button it would setState and set logging_in = true.
StaticButton:
RaisedButton(
child: Text("Login"),
onPressed: () {
setState(() {
logging_in = true;
});
}
)
The above is what I tried. Should accomplish the effect, but is definitely not elegant. Is there a better way to achieve this?
What you have isn't that far off. You have a logging_in variable that tells you when to show the CircularProgressIndicator already, which is a good start. The only thing is that FutureBuilder has no use here. It's meant for retrieving data from Futures that need to be displayed in the UI.
What you need to do is call logMeIn in the onPressed of your "Static button" as shown here:
StaticButton:
RaisedButton(
child: Text("Login"),
onPressed: () async {
setState(() {
logging_in = true;
});
await logMeIn();
setState(() {
logging_in = false;
});
}
)
You don't need to switch out the whole button when logging_in changes, just the child of the button.
StaticButton(with child switching):
RaisedButton(
child: logging_in ? CircularProgressIndicator() : Text("Login"),
onPressed: () async {
setState(() {
logging_in = true;
});
await logMeIn();
setState(() {
logging_in = false;
});
}
)
You also probably want to add another bool to prevent multiple clicks of the button while its loading. As a note in using FutureBuilder and essentially any other builder in flutter, you always need to return a widget from the builder function, which your current implementation does not do.
How does setState actually work?
It seems to not do what I expect it to do when the Widget which should have been rebuilt is built in a builder function. The current issue I have is with a ListView.builder and buttons inside an AlertDialog.
One of the buttons here is an "AutoClean" which will automatically remove certain items from the list show in the dialog.
Note: The objective here is to show a confirmation with a list of "Jobs" which will be submitted. The jobs are marked to show which ones appear to be invalid. The user can go Back to update the parameters, or press "Auto Clean" to remove the ones that are invalid.
The button onTap looks like this:
GeneralButton(
color: Colors.yellow,
label: 'Clear Overdue',
onTap: () {
print('Nr of jobs BEFORE: ${jobQueue.length}');
for (int i = jobQueue.length - 1; i >= 0; i--) {
print('Checking item at $i');
Map task = jobQueue[i];
if (cuttoffTime.isAfter(task['dt'])) {
print('Removing item $i');
setState(() { // NOT WORKING
jobQueue = List<Map<String, dynamic>>.from(jobQueue)
..removeAt(i); // THIS WORKS
});
}
}
print('Nr of jobs AFTER: ${jobQueue.length}');
updateTaskListState(); // NOT WORKING
print('New Task-list state: $taskListState');
},
),
Where jobQueue is used as the source for building the ListView.
updateTaskListState looks like this:
void updateTaskListState() {
DateTime cuttoffTime = DateTime.now().add(Duration(minutes: 10));
if (jobQueue.length == 0) {
setState(() {
taskListState = TaskListState.empty;
});
return;
}
bool allDone = true;
bool foundOverdue = false;
for (Map task in jobQueue) {
if (task['result'] == null) allDone = false;
if (cuttoffTime.isAfter(task['dt'])) foundOverdue = true;
}
if (allDone) {
setState(() {
taskListState = TaskListState.done;
});
return;
}
if (foundOverdue) {
setState(() {
taskListState = TaskListState.needsCleaning;
});
return;
}
setState(() {
taskListState = TaskListState.ready;
});
}
TaskListState is simply an enum used to decide whether the job queue is ready to be submitted.
The "Submit" button should become active once the taskListState is set to TaskListState.ready. The AlertDialog button row uses the taskListState for that like this:
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
mainAxisSize: MainAxisSize.max,
children: <Widget>[
if (taskListState == TaskListState.ready)
ConfirmButton(
onTap: (isValid && isOnlineNow)
? () {
postAllInstructions().then((_) {
updateTaskListState();
// navigateBack();
});
: null),
From the console output I can see that that is happening but it isn't working. It would appear to be related to the same issue.
I don't seem to have this kind of problem when I have all the widgets built using a simple widget tree inside of build. But in this case I'm not able to update the display of the dialog to show the new list without the removed items.
This post is getting long but the ListView builder, inside the AleryDialog, looks like this:
Flexible(
child: ListView.builder(
itemBuilder: (BuildContext context, int itemIndex) {
DateTime itemTime = jobQueue[itemIndex]['dt'];
bool isPastCutoff = itemTime.isBefore(cuttoffTime);
return Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
mainAxisSize: MainAxisSize.max,
children: <Widget>[
Text(
userDateFormat.format(itemTime),
style: TextStyle(
color:
isPastCutoff ? Colors.deepOrangeAccent : Colors.blue,
),
),
Icon(
isPastCutoff ? Icons.warning : Icons.cached,
color: isPastCutoff ? Colors.red : Colors.green,
)
],
);
},
itemCount: jobQueue.length,
),
),
But since the Row() with buttons also doesn't react to setState I doubt that the problem lies within the builder function itself.
FWIW all the code, except for a few items like "GeneralButton" which is just a boilerplate widget, resides in the State class for the Screen.
My gut-feeling is that this is related to the fact that jobQueue is not passed to any of the widgets. The builder function refers to jobQueue[itemIndex], where it accesses the jobQueue attribute directly.
I might try to extract the AlertDialog into an external Widget. Doing so will mean that it can only access jobQueue if it is passed to the Widget's constructor....
Since you are writing that this is happening while using a dialog, this might be the cause of your problem:
https://api.flutter.dev/flutter/material/showDialog.html
The setState call inside your dialog therefore won't trigger the desired UI rebuild of the dialog content. As stated in the API a short and easy way to achieve a rebuild in another context would be to use the StatefulBuilder widget:
showDialog(
context: context,
builder: (dialogContext) {
return StatefulBuilder(
builder: (stateContext, setInnerState) {
// return your dialog widget - Rows in ListView in Container
...
// call it directly as part of onTap of a widget of yours or
// pass the setInnerState down to another widgets
setInnerState((){
...
})
}
);
EDIT
There are, as in almost every case in the programming world, various approaches to handle the setInnerState call to update the dialog UI. It highly depends on the general way of how you decided to manage data flow / management and logic separation. As an example I use your GeneralButton widget (assuming it is a StatefulWidget):
class GeneralButton extends StatefulWidget {
// all your parameters
...
// your custom onTap you provide as instantiated
final VoidCallback onTap;
GeneralButton({..., this.onTap});
#override
State<StatefulWidget> createState() => _GeneralButtonState();
}
class _GeneralButtonState extends State<GeneralButton> {
...
#override
Widget build(BuildContext context) {
// can be any widget acting as a button - Container, GestureRecognizer...
return MaterialButton(
...
onTap: {
// your button logic which has either been provided fully
// by the onTap parameter or has some fixed code which is
// being called every time
...
// finally calling the provided onTap function which has the
// setInnerState call!
widget.onTap();
},
);
}
If you have no fixed logic in your GeneralButton widget, you can write: onTap: widget.onTap
This would result in using your GeneralButton as follows:
...
GeneralButton(
...
onTap: {
// the desired actions like provided in your first post
...
// calling setInnerState to trigger the dialog UI rebuild
setInnerState((){});
},
)