Creating a variable with an onTap navigator flutter - dart

Question

This will be a lot of explaining but i hope someone will be able to help.
Currently i have search button on my appbar that, when pressed, covers over my appbar title with a textfield
The normal appbar title is an image and i am adding functionality that when pressed, it brings you to the home screen. This is were it gets tricky, because i need to use this line of code to accomplish just that
new InkWell (
child: Image.asset(
'images/logoGrey.png',
fit: BoxFit.fill,
),
onTap: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) =>
LandingPage(),
),
);
},
);
so i set that to a variable like so
class _ControlsPageState extends State<ControlsPage> {
Widget appBarTitle = new InkWell (
child: Image.asset(
'images/logoGrey.png',
fit: BoxFit.fill,
),
onTap: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) =>
LandingPage(),
),
);
},
);
The reason i have this variable is so that i can change the state of the appbar(title) to a textfield when i click on the search button and back to the image when i close out.
but this wont work (error on "context") seeing as though this line of code below can only be used under "Widget build(BuildContext context)" and not in my class....
onTap: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) =>
LandingPage(),
),
);
},
The bottom line is i need my appbar title to be a callback to the variable "appBarTitle", and the variable gets an error on "context", is there anyway i can make this work?
here is the appbar code in case it helps
appBar: AppBar(
iconTheme: new IconThemeData(color: Theme.CompanyColors.coolGrey),
backgroundColor: Colors.white,
centerTitle: true,
title: appBarTitle ,
actions: <Widget>[
new IconButton(
icon: actionIcon,
onPressed: () {
setState(() {
if (this.actionIcon.icon == Icons.search) {
this.actionIcon =
new Icon(Icons.close, color: Theme.CompanyColors.coolGrey);
this.appBarTitle = new TextField(
onSubmitted: (String str) {
setState(() {
result = str;
});
controller.text = "";
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => ControlSearchPage(
search: result, title: "${widget.title}"),
),
);
},
style: new TextStyle(
color: Colors.black,
),
decoration: new InputDecoration(
prefixIcon:
new Icon(Icons.search, color: Theme.CompanyColors.coolGrey),
hintText: "Search...",
hintStyle: new TextStyle(color: Theme.CompanyColors.coolGrey)),
);
} else {
this.actionIcon =
new Icon(Icons.search, color: Theme.CompanyColors.coolGrey);
this.appBarTitle = new InkWell (
child: Image.asset(
'images/logoGrey.png',
fit: BoxFit.fill,
),
onTap: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) =>
LandingPage(),
),
);
},
);
}
});
},
),
],
),
any comments will be appreciated

Answer 1

You should change appBarTitle to be a method that can generate the widget on state change rather than saving it to a variable. This way, you can ensure that it will only be generated when context is available.
// Define a bool to hold the current search state
bool _isSearching = false;
...
// In your build method
appBar: AppBar(
iconTheme: new IconThemeData(color: Theme.CompanyColors.coolGrey),
backgroundColor: Colors.white,
centerTitle: true,
title: _buildAppBarTitle(),
actions: <Widget>[
new IconButton(
icon: _isSearching
? new Icon(Icons.close, color: Theme.CompanyColors.coolGrey)
: new Icon(Icons.search, color: Theme.CompanyColors.coolGrey),
onPressed: () {
setState(() => _isSearching = !_isSearching);
},
),
],
),
...
// Define a separate method to build the appBarTitle
Widget _buildAppBarTitle() {
if (_isSearching) {
return new TextField(
onSubmitted: (String str) {
setState(() {
result = str;
});
controller.text = "";
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => ControlSearchPage(
search: result, title: "${widget.title}"),
),
);
},
style: new TextStyle(
color: Colors.black,
),
decoration: new InputDecoration(
prefixIcon:
new Icon(Icons.search, color: Theme.CompanyColors.coolGrey),
hintText: "Search...",
hintStyle: new TextStyle(color: Theme.CompanyColors.coolGrey)),
);
} else {
return new InkWell (
child: Image.asset(
'images/logoGrey.png',
fit: BoxFit.fill,
),
onTap: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) =>
LandingPage(),
),
);
},
);
}