Expandable ListView / dynamic TreeView in Flutter - flutter

Question

I need a nested TreeView where going through a list and build nodes based on parent child realationship. When tapping on a node it expands and shows its children with indentation. Also changing textstyle color of selectedt node..and 2d scrollable if the list is very long and has many nodes with children themselves having many children. How? please help.

Answer 1

You can copy paste run full code below
You can use package https://pub.dev/packages/flutter_treeview
It has some features you can customize, you can see working demo below
For parent child relation, you can see initState() in full code
#override
void initState() {
_nodes = [
Node(
label: 'documents',
key: 'docs',
expanded: docsOpen,
icon: NodeIcon(
codePoint:
docsOpen ? Icons.folder_open.codePoint : Icons.folder.codePoint,
color: "blue",
),
children: [
Node(
label: 'personal',
key: 'd3',
code snippet
TreeView(
controller: _treeViewController,
allowParentSelect: _allowParentSelect,
supportParentDoubleTap: _supportParentDoubleTap,
onExpansionChanged: (key, expanded) =>
_expandNode(key, expanded),
onNodeTap: (key) {
debugPrint('Selected: $key');
setState(() {
_selectedNode = key;
_treeViewController =
_treeViewController.copyWith(selectedKey: key);
});
},
theme: _treeViewTheme,
)
working demo
full code
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_treeview/tree_view.dart';
import 'dart:convert';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'TreeView Example',
home: MyHomePage(title: 'TreeView Example'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
String _selectedNode;
List<Node> _nodes;
TreeViewController _treeViewController;
bool docsOpen = true;
final Map<ExpanderPosition, Widget> expansionPositionOptions = const {
ExpanderPosition.start: Text('Start'),
ExpanderPosition.end: Text('End'),
};
final Map<ExpanderType, Widget> expansionTypeOptions = const {
ExpanderType.caret: Icon(
Icons.arrow_drop_down,
size: 28,
),
ExpanderType.arrow: Icon(Icons.arrow_downward),
ExpanderType.chevron: Icon(Icons.expand_more),
ExpanderType.plusMinus: Icon(Icons.add),
};
final Map<ExpanderModifier, Widget> expansionModifierOptions = const {
ExpanderModifier.none: ModContainer(ExpanderModifier.none),
ExpanderModifier.circleFilled: ModContainer(ExpanderModifier.circleFilled),
ExpanderModifier.circleOutlined:
ModContainer(ExpanderModifier.circleOutlined),
ExpanderModifier.squareFilled: ModContainer(ExpanderModifier.squareFilled),
ExpanderModifier.squareOutlined:
ModContainer(ExpanderModifier.squareOutlined),
};
ExpanderPosition _expanderPosition = ExpanderPosition.start;
ExpanderType _expanderType = ExpanderType.caret;
ExpanderModifier _expanderModifier = ExpanderModifier.none;
bool _allowParentSelect = false;
bool _supportParentDoubleTap = false;
#override
void initState() {
_nodes = [
Node(
label: 'documents',
key: 'docs',
expanded: docsOpen,
icon: NodeIcon(
codePoint:
docsOpen ? Icons.folder_open.codePoint : Icons.folder.codePoint,
color: "blue",
),
children: [
Node(
label: 'personal',
key: 'd3',
icon: NodeIcon.fromIconData(Icons.input),
children: [
Node(
label: 'Resume.docx',
key: 'pd1',
icon: NodeIcon.fromIconData(Icons.insert_drive_file)),
Node(
label: 'Cover Letter.docx',
key: 'pd2',
icon: NodeIcon.fromIconData(Icons.insert_drive_file)),
]),
Node(
label: 'Inspection.docx',
key: 'd1',
// icon: NodeIcon.fromIconData(Icons.insert_drive_file),
),
Node(
label: 'Invoice.docx',
key: 'd2',
icon: NodeIcon.fromIconData(Icons.insert_drive_file)),
],
),
Node(
label: 'MeetingReport.xls',
key: 'mrxls',
icon: NodeIcon.fromIconData(Icons.insert_drive_file)),
Node(
label: 'MeetingReport.pdf',
key: 'mrpdf',
icon: NodeIcon.fromIconData(Icons.insert_drive_file)),
Node(
label: 'Demo.zip',
key: 'demo',
icon: NodeIcon.fromIconData(Icons.archive)),
];
_treeViewController = TreeViewController(
children: _nodes,
selectedKey: _selectedNode,
);
super.initState();
}
ListTile _makeExpanderPosition() {
return ListTile(
title: Text('Expander Position'),
dense: true,
trailing: CupertinoSlidingSegmentedControl(
children: expansionPositionOptions,
groupValue: _expanderPosition,
onValueChanged: (ExpanderPosition newValue) {
setState(() {
_expanderPosition = newValue;
});
},
),
);
}
SwitchListTile _makeAllowParentSelect() {
return SwitchListTile.adaptive(
title: Text('Allow Parent Select'),
dense: true,
value: _allowParentSelect,
onChanged: (v) {
setState(() {
_allowParentSelect = v;
});
},
);
}
SwitchListTile _makeSupportParentDoubleTap() {
return SwitchListTile.adaptive(
title: Text('Support Parent Double Tap'),
dense: true,
value: _supportParentDoubleTap,
onChanged: (v) {
setState(() {
_supportParentDoubleTap = v;
});
},
);
}
ListTile _makeExpanderType() {
return ListTile(
title: Text('Expander Style'),
dense: true,
trailing: CupertinoSlidingSegmentedControl(
children: expansionTypeOptions,
groupValue: _expanderType,
onValueChanged: (ExpanderType newValue) {
setState(() {
_expanderType = newValue;
});
},
),
);
}
ListTile _makeExpanderModifier() {
return ListTile(
title: Text('Expander Modifier'),
dense: true,
trailing: CupertinoSlidingSegmentedControl(
children: expansionModifierOptions,
groupValue: _expanderModifier,
onValueChanged: (ExpanderModifier newValue) {
setState(() {
_expanderModifier = newValue;
});
},
),
);
}
#override
Widget build(BuildContext context) {
TreeViewTheme _treeViewTheme = TreeViewTheme(
expanderTheme: ExpanderThemeData(
type: _expanderType,
modifier: _expanderModifier,
position: _expanderPosition,
color: Colors.grey.shade800,
size: 20,
),
labelStyle: TextStyle(
fontSize: 16,
letterSpacing: 0.3,
),
parentLabelStyle: TextStyle(
fontSize: 16,
letterSpacing: 0.1,
fontWeight: FontWeight.w800,
color: Colors.blue.shade700,
),
iconTheme: IconThemeData(
size: 18,
color: Colors.grey.shade800,
),
colorScheme: Theme.of(context).brightness == Brightness.light
? ColorScheme.light(
primary: Colors.blue.shade50,
onPrimary: Colors.grey.shade900,
background: Colors.transparent,
onBackground: Colors.black,
)
: ColorScheme.dark(
primary: Colors.black26,
onPrimary: Colors.white,
background: Colors.transparent,
onBackground: Colors.white70,
),
);
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
elevation: 0,
),
body: GestureDetector(
onTap: () {
FocusScope.of(context).requestFocus(FocusNode());
},
child: Container(
color: Colors.grey.shade200,
padding: EdgeInsets.all(20),
height: double.infinity,
child: Column(
children: <Widget>[
Container(
height: 300,
child: Column(
children: <Widget>[
_makeExpanderPosition(),
_makeExpanderType(),
_makeExpanderModifier(),
_makeAllowParentSelect(),
_makeSupportParentDoubleTap(),
],
),
),
Expanded(
child: Container(
decoration: BoxDecoration(
color: Colors.white,
borderRadius: BorderRadius.circular(10),
),
padding: EdgeInsets.all(10),
child: TreeView(
controller: _treeViewController,
allowParentSelect: _allowParentSelect,
supportParentDoubleTap: _supportParentDoubleTap,
onExpansionChanged: (key, expanded) =>
_expandNode(key, expanded),
onNodeTap: (key) {
debugPrint('Selected: $key');
setState(() {
_selectedNode = key;
_treeViewController =
_treeViewController.copyWith(selectedKey: key);
});
},
theme: _treeViewTheme,
),
),
),
GestureDetector(
onTap: () {
debugPrint('Close Keyboard');
FocusScope.of(context).unfocus();
},
child: Container(
padding: EdgeInsets.only(top: 20),
alignment: Alignment.center,
child: Text(_treeViewController.getNode(_selectedNode) == null
? ''
: _treeViewController.getNode(_selectedNode).label),
),
)
],
),
),
),
bottomNavigationBar: SafeArea(
top: false,
child: ButtonBar(
alignment: MainAxisAlignment.spaceEvenly,
children: <Widget>[
CupertinoButton(
child: Text('Node'),
onPressed: () {
setState(() {
_treeViewController = _treeViewController.copyWith(
children: _nodes,
);
});
},
),
CupertinoButton(
child: Text('JSON'),
onPressed: () {
setState(() {
_treeViewController =
_treeViewController.loadJSON(json: US_STATES_JSON);
});
},
),
CupertinoButton(
child: Text('Toggle'),
onPressed: _treeViewController.selectedNode != null &&
_treeViewController.selectedNode.isParent
? () {
setState(() {
_treeViewController = _treeViewController
.withToggleNode(_treeViewController.selectedKey);
});
}
: null,
),
CupertinoButton(
child: Text('Edit'),
onPressed: () {
TextEditingController editingController = TextEditingController(
text: _treeViewController.selectedNode.label);
showCupertinoDialog(
context: context,
builder: (context) {
return CupertinoAlertDialog(
title: Text('Edit Label'),
content: Container(
height: 80,
alignment: Alignment.center,
padding: EdgeInsets.all(10),
child: CupertinoTextField(
controller: editingController,
autofocus: true,
),
),
actions: <Widget>[
CupertinoDialogAction(
child: Text('Cancel'),
isDestructiveAction: true,
onPressed: () => Navigator.of(context).pop(),
),
CupertinoDialogAction(
child: Text('Update'),
isDefaultAction: true,
onPressed: () {
if (editingController.text.isNotEmpty) {
setState(() {
Node _node = _treeViewController.selectedNode;
_treeViewController =
_treeViewController.withUpdateNode(
_treeViewController.selectedKey,
_node.copyWith(
label: editingController.text));
});
debugPrint(editingController.text);
}
Navigator.of(context).pop();
},
),
],
);
});
},
),
],
),
),
);
}
_expandNode(String key, bool expanded) {
String msg = '${expanded ? "Expanded" : "Collapsed"}: $key';
debugPrint(msg);
Node node = _treeViewController.getNode(key);
if (node != null) {
List<Node> updated;
if (key == 'docs') {
updated = _treeViewController.updateNode(
key,
node.copyWith(
expanded: expanded,
icon: NodeIcon(
codePoint: expanded
? Icons.folder_open.codePoint
: Icons.folder.codePoint,
color: expanded ? "blue600" : "grey700",
)),
);
} else {
updated = _treeViewController.updateNode(
key, node.copyWith(expanded: expanded));
}
setState(() {
if (key == 'docs') docsOpen = expanded;
_treeViewController = _treeViewController.copyWith(children: updated);
});
}
}
}
class ModContainer extends StatelessWidget {
final ExpanderModifier modifier;
const ModContainer(this.modifier, {Key key}) : super(key: key);
#override
Widget build(BuildContext context) {
double _borderWidth = 0;
BoxShape _shapeBorder = BoxShape.rectangle;
Color _backColor = Colors.transparent;
Color _backAltColor = Colors.grey.shade700;
switch (modifier) {
case ExpanderModifier.none:
break;
case ExpanderModifier.circleFilled:
_shapeBorder = BoxShape.circle;
_backColor = _backAltColor;
break;
case ExpanderModifier.circleOutlined:
_borderWidth = 1;
_shapeBorder = BoxShape.circle;
break;
case ExpanderModifier.squareFilled:
_backColor = _backAltColor;
break;
case ExpanderModifier.squareOutlined:
_borderWidth = 1;
break;
}
return Container(
decoration: BoxDecoration(
shape: _shapeBorder,
border: _borderWidth == 0
? null
: Border.all(
width: _borderWidth,
color: _backAltColor,
),
color: _backColor,
),
width: 15,
height: 15,
);
}
}
const List<Map<String, dynamic>> US_STATES = [
{
"label": "A",
"children": [
{"label": "Alabama", "key": "AL"},
{"label": "Alaska", "key": "AK"},
{"label": "American Samoa", "key": "AS"},
{"label": "Arizona", "key": "AZ"},
{"label": "Arkansas", "key": "AR"}
]
},
{
"label": "C",
"children": [
{"label": "California", "key": "CA"},
{"label": "Colorado", "key": "CO"},
{"label": "Connecticut", "key": "CT"},
]
},
{
"label": "D",
"children": [
{"label": "Delaware", "key": "DE"},
{"label": "District Of Columbia", "key": "DC"},
]
},
{
"label": "F",
"children": [
{"label": "Federated States Of Micronesia", "key": "FM"},
{"label": "Florida", "key": "FL"},
]
},
{
"label": "G",
"children": [
{"label": "Georgia", "key": "GA"},
{"label": "Guam", "key": "GU"},
]
},
{
"label": "H",
"children": [
{"label": "Hawaii", "key": "HI"},
]
},
{
"label": "I",
"children": [
{"label": "Idaho", "key": "ID"},
{"label": "Illinois", "key": "IL"},
{"label": "Indiana", "key": "IN"},
{"label": "Iowa", "key": "IA"},
]
},
{
"label": "K",
"children": [
{"label": "Kansas", "key": "KS"},
{"label": "Kentucky", "key": "KY"},
]
},
{
"label": "L",
"children": [
{"label": "Louisiana", "key": "LA"},
]
},
{
"label": "M",
"children": [
{"label": "Maine", "key": "ME"},
{"label": "Marshall Islands", "key": "MH"},
{"label": "Maryland", "key": "MD"},
{"label": "Massachusetts", "key": "MA"},
{"label": "Michigan", "key": "MI"},
{"label": "Minnesota", "key": "MN"},
{"label": "Mississippi", "key": "MS"},
{"label": "Missouri", "key": "MO"},
{"label": "Montana", "key": "MT"},
]
},
{
"label": "N",
"children": [
{"label": "Nebraska", "key": "NE"},
{"label": "Nevada", "key": "NV"},
{"label": "New Hampshire", "key": "NH"},
{"label": "New Jersey", "key": "NJ"},
{"label": "New Mexico", "key": "NM"},
{"label": "New York", "key": "NY"},
{"label": "North Carolina", "key": "NC"},
{"label": "North Dakota", "key": "ND"},
{"label": "Northern Mariana Islands", "key": "MP"},
]
},
{
"label": "O",
"children": [
{"label": "Ohio", "key": "OH"},
{"label": "Oklahoma", "key": "OK"},
{"label": "Oregon", "key": "OR"},
]
},
{
"label": "P",
"children": [
{"label": "Palau", "key": "PW"},
{"label": "Pennsylvania", "key": "PA"},
{"label": "Puerto Rico", "key": "PR"},
]
},
{
"label": "R",
"children": [
{"label": "Rhode Island", "key": "RI"},
]
},
{
"label": "S",
"children": [
{"label": "South Carolina", "key": "SC"},
{"label": "South Dakota", "key": "SD"},
]
},
{
"label": "T",
"children": [
{"label": "Tennessee", "key": "TN"},
{"label": "Texas", "key": "TX"},
]
},
{
"label": "U",
"children": [
{"label": "Utah", "key": "UT"},
]
},
{
"label": "V",
"children": [
{"label": "Vermont", "key": "VT"},
{"label": "Virgin Islands", "key": "VI"},
{"label": "Virginia", "key": "VA"},
]
},
{
"label": "W",
"children": [
{"label": "Washington", "key": "WA"},
{"label": "West Virginia", "key": "WV"},
{"label": "Wisconsin", "key": "WI"},
{"label": "Wyoming", "key": "WY"}
]
},
];
String US_STATES_JSON = jsonEncode(US_STATES);