Click Here for Image! Click here to see error when i input 'itemCount' I want to ask, I am having trouble using the List.builder () feature. where I can't limit the data contained in the list so that it will display an error message about the error range. Here is the source code that I gave.
_sort = <Sort>[
Sort(
category: 'By Games',
item: new Container(
height: 200,
child: new Container(
child: ListView.builder(
scrollDirection: Axis.vertical,
//itemCount: allGames['games'].length,
itemBuilder: (context, index) {
return Container(
child: Padding(
padding: const EdgeInsets.all(15),
child: Text(allGames['games'][index]['game_title'].toString(), style: new TextStyle(color: Colors.white)),
),
);
},
)))),
and here i call the 'Category' and 'Item'. I wrap it in a wrap widget. then for categories, I did divide it into 3 parts. then every part in the category I named 'items' and the problem is the items here have excess capacity so that the data displayed is leftover and not on target.
child: Wrap(
children: <Widget>[
ListView.builder(
shrinkWrap: true,
itemCount: 3,
itemBuilder: (context, index) {
context = context;
if (index < 2) {
final sort = _sort[index];
return ExpansionTile(
title: ListTile(
title: Text(
sort.category,
style: TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
),
),
children: <Widget>[
ListTile(
title: sort.item,
)
],
);
} else {
),
You're accessing allGames["games"] and it says that you're trying to use [] on null.
Seems like allGames is null, so put an eye on that.
Other than that, your use of itemCount is fine!
You can add some null awareness by doing something like this:
itemCount = allGames != null ? (allGames["games"]?.length ?? 0) : 0
I think when the build method runs at the first time, your allGames is null. So, try to add a default value, for example:
itemCount: allGames['games'].length ?? 0
Related
I don't know if stretching is the correct word to describe it.
But it looks like this.
"last message 👋👋" is the last message in this convo and the empty space below is the 'stretching'. Once I release the touch from my screen it goes back to normal. I want to disable that 'stretching' so that nothing happens when the user overscrolls.
ListView code:
ListView.builder(
controller: _controller1,
physics: BouncingScrollPhysics(),
itemCount: snapshot.data!.docs.length, //snapshot from parent StreamBuilder
itemBuilder: (context, index) {
final allowedOrNot = index == 0
? true
: compareDate( // Userdefined function to check if the dates above messages should be displayed or not
currentSnap: snapshot.data!.docs[index]
.data()['serverTimeStamp'],
previousSnap: snapshot.data!.docs[index - 1]
.data()['serverTimeStamp']);
return Column(
children: [
allowedOrNot
? chatDater( // the date widget (above some messages to indicate the date of conversation)
data: dataForChatDater( // Userdefined function which returns Strings like 'Yesterday', 'Today' for the widget to display
snap: snapshot.data!.docs[index]
.data()['serverTimeStamp']),
)
: const SizedBox(
width: 0,
height: 0,
),
Align(
alignment:
snapshot.data!.docs[index].data()['sender'] ==
widget.usernameOfFriend
? Alignment.centerLeft
: Alignment.centerRight,
child: MessageBubble( // The ChatBubble widget used to display the messages
timestamp: snapshot.data!.docs[index]
.data()['serverTimeStamp'],
message: snapshot.data!.docs[index].data()['message'],
IsYou: snapshot.data!.docs[index].data()['sender'] ==
widget.usernameOfFriend
? false
: true,
),
),
],
);
},
),
It is natural behavior of BouncingScrollPhysics.
If you don't want to overscroll, you can change it to NeverScrollableScrollPhysics.
Try shrinkWrap:true in your ListView.builder and mainAxisSize:MainAxisSize.min in Column as follows:
ListView.builder(
//other
shrinkWrap: true,
itemBuilder: (context, index) {
return Column(
mainAxisSize: MainAxisSize.min, //use this
children: [
//your children
],
);
})
I am new to the flutter and trying to fill the empty space in the listtile. I tried to use dense and visualDensity but with that, I am not getting the required result. Any support and suggestions will be appreciated.
here is my code and output:
Column(
crossAxisAlignment: CrossAxisAlignment.end,
children: [
SizedBox(
height: isLargeScreen ? 300 : 200,
child: ListView.builder(
physics: const ScrollPhysics(),
shrinkWrap: true,
itemCount: tags.length,
itemBuilder: (context, index) {
return CheckboxListTile(
value: tempSelectedTags.contains(tags[index].id),
onChanged: (e) {
setState(() {
if (tempSelectedTags.contains(tags[index].id)) {
tempSelectedTags.remove(tags[index].id);
} else {
tempSelectedTags.add(tags[index].id);
}
});
},
title: Text(
tags[index].name,
style: !tempSelectedTags.contains(tags[index].id)
? theme.textTheme.labelMedium?.copyWith(
color: ThemeConfig.colorTertiary)
: theme.textTheme.titleSmall?.copyWith(
color: ThemeConfig.colorTertiary),
),
);
}),
),
const Spacer(),
Padding(
padding: const EdgeInsets.only(bottom:sdPaddingMedium),
child: SdPrimaryButton(
title: appLocalizations.btnApply,
onPressed: () {
viewModel.setTags(tempSelectedTags);
Navigator.pop(context);
},
),
),
],
)
Output can be seen here
There are two important things that determine the vertical layout in your column.
The whole box has a fixed size
SizedBox(
height: isLargeScreen ? 300 : 200,
There is a flexible space between the checkbox options and the bottom-right button
const Spacer(),
So if you want to remove the space, you can either
reduce the overall box size or
replace the const Spacer with a constant spacing like
SizedBox(height: 50) and also remove the SizedBox, so that the whole box will be content-sized
I am getting an error while trying to compile my code could anyone help me fix it? I am trying to create a list of buttons that will navigate to another screen. It was previously a expansion tile and I am trying to switch it to a list tile.
return ListTile(
title: Text(StudyViewModel.studies[index].name,
style: TextStyle(fontSize: 18.0)),
children: <Widget>[
ListView.builder(
shrinkWrap: true,
physics: ClampingScrollPhysics(),
itemCount: StudyViewModel.studies[index].tasks.length,
itemBuilder: (context, int taskIndex) {
return ListTile(
title: Text(StudyViewModel.studies[index].tasks[taskIndex].name),
contentPadding: EdgeInsets.symmetric(horizontal: 32.0),
subtitle: Text(
StudyViewModel.studies[index].tasks[taskIndex].elapsedTime),
);
},
),
Based off of responses, the goal of this code is to create a list of buttons that have previously been defined in a template. These buttons will be used in a time study app. I would like to be able to upload the activities into a new page. Originally, the code was written as an expansiontile, but I am trying to change it to a listtile. The error we are encountering is:
lib/pages/home_page.dart:107:7: Error: No named parameter with the name 'children'.
children: [
^^^^^^^^
../../lib/flutter/packages/flutter/lib/src/material/list_tile.dart:762:9: Context: Found this candidate, but the arguments don't match.
const ListTile({
^^^^^^^^
Failed to compile application
Error code for ListView
The ListTile widget doesn't contain a parameter named children. In your code you're setting a parameter 'children' which is invalid.
This might help:
return ListView(
children: <Widget>[
Text(StudyViewModel.studies[index].name,
style: TextStyle(fontSize: 18.0),
),
ListView.builder(
shrinkWrap: true,
primary: false,
itemCount: StudyViewModel.studies[index].tasks.length,
itemBuilder: (context, int taskIndex) {
return ListTile(
title: Text(StudyViewModel.studies[index].tasks[taskIndex].name),
contentPadding: EdgeInsets.symmetric(horizontal: 32.0),
subtitle: Text(StudyViewModel.studies[index].tasks[taskIndex].elapsedTime),
);
},
),
I am trying to display a row of buttons. Since the number of buttons depends on the number of elements in a List, I have to use GridView.builder to dynamically create the right amount of buttons. Unfortunately it seems that GridView.builder is taking up alot of unnecessary space. Anyone know what is wrong here?
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
// Dice buttons
Flexible(
child: GridView.builder(
itemCount: dices.length,
gridDelegate: new SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: dices.length,
),
itemBuilder: (BuildContext context, int index) {
return new Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
ButtonTheme(
minWidth: 50.0,
height: 50.0,
child: RaisedButton(
child: Text(
dices[index].toString(),
style: TextStyle(
fontSize: 20,
color: Colors.white,
),
),
color: usedDices[index] || !expectNum
? Colors.grey
: Colors.black,
onPressed: () {
if (!usedDices[index] && expectNum) {
setState(() {
numUsed[turn] = dices[index].toString();
numUsedIndex[turn] = index;
});
expectNum = false;
usedDices[index] = true;
}
},
),
),
]);
})),
Link to Pic: https://drive.google.com/file/d/1_Jr4rz9GJ-D8-Xjxs2w8Sn8lOdnBBqTc/view?usp=sharing
As you can see are lots of unnecessary space here and it seems to be the reuslt of GridView.builder
That space is the result of Flexible, which fills the available space. You will see that if you replace it with a Container and give it a height, it won't produce that much space below.
Just had this problem, top SliverPadding is set to 20.0 by default. Looking at docs I see:
/// By default, [ListView] will automatically pad the list's scrollable
/// extremities to avoid partial obstructions indicated by [MediaQuery]'s
/// padding. To avoid this behavior, override with a zero [padding] property.
So,
GridView.builder(
// shrinkWrap: true,
padding: EdgeInsets.zero,
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisSpacing: 1,
mainAxisSpacing: 1,
crossAxisCount: 3,
),
itemBuilder: (context, index) {
return Container(
color: Colors.black,
);
},
itemCount: 10,
),
or
If you put a widget before the ListView, you should wrap the ListView with a
MediaQuery.removePadding widget (with removeTop: true)
AlertCardWidget is a widget that i wrote. I return it in itemBuilder but nothing shown. Here is my code:
Flexible(
child: Padding(
child: SingleChildScrollView(
child: ListView.builder(
itemCount: state.data.length,
itemBuilder: (BuildContext context, int index) {
state.data["datas"].map<Widget>((f) {
return AlertCardWidget(
positionId: "${f["8020074"]}",
shipowner: "${f["8020076"]}",
customer: "${f["8020170"]}",
salesRepresenter: "${f["8020176"]}",
operationRepresenter: "${f["8020177"]}",
textContentFontColor:
AppTheme(Theme.of(context).brightness)
.cardFontBackgroundColor,
textfont: Colors.redAccent,
);
}).toList();
},
),
),
),
),
No error to show.
I have items that why I use ListView. The problom of using Listview instead ListView.builder is taking "Vertical viewport was given unbounded height error". The problem has solved when writing Listview like child of Expanded widget. Here is my code:
Expanded(
child: Padding(
padding: const EdgeInsets.all(4.0),
child: ListView(
children: state.data["datas"].map<Widget>((f) => AlertCardWidget(positionId: "${f["8020074"]}",
shipowner: "${f["8020076"]}",
customer: "${f["8020170"]}",
salesRepresenter: "${f["8020176"]}",
operationRepresenter: "${f["8020177"]}",
textContentFontColor: AppTheme(Theme.of(context).brightness).cardFontBackgroundColor,
textfont: Colors.redAccent,)).toList(),
),
),
),
Maybe a silly question, but why are you mapping a list into a ListView.builder?
Have you tried using the index for each iteration instead?
Because what I understand from that code is that every ["datas"] item you've got will generate the whole list for as many times as state.data.length has.
Maybe try this out:
Flexible(
child: Padding(
child: SingleChildScrollView(
child: ListView.builder(
itemCount: state.data.length,
itemBuilder: (BuildContext context, int index) {
return AlertCardWidget(
positionId: state.data[index]["datas"]["8020074"],
shipowner: state.data[index]["datas"]["8020076"],
customer: state.data[index]["datas"]["8020170"],
salesRepresenter: state.data[index]["datas"]["8020176"],
operationRepresenter: state.data[index]["datas"]["8020177"],
textContentFontColor:
AppTheme(Theme.of(context).brightness)
.cardFontBackgroundColor,
textfont: Colors.redAccent,
);
},
),
),
),
),
If that doesn't work, would you mind showing us which data are you trying to retrieve?
Your itemBuilder function does not return a value.
Edit: It should return a single Widget for every entry in your list.
Something like this should work.
Also, Padding Widget is missing the padding property.
Flexible(
child: Padding(
child: SingleChildScrollView(
child: ListView.builder(
itemCount: state.data.length,
itemBuilder: (BuildContext context, int index) {
final f = state.data[index];
return AlertCardWidget(
positionId: "${f["8020074"]}",
shipowner: "${f["8020076"]}",
customer: "${f["8020170"]}",
salesRepresenter: "${f["8020176"]}",
operationRepresenter: "${f["8020177"]}",
textContentFontColor:
AppTheme(Theme.of(context).brightness)
.cardFontBackgroundColor,
textfont: Colors.redAccent,
);
},
),
),
),
),