CODEWITHSUNDEEP
flutterconstructorroutes
RAJA SAHAB
RAJA SAHAB

Reputation: 3

Routing error shows missing one argument?

This is how i am routing to next page , 

   '/ot1': (context) => CustomListView(),

and it was working fine onTAP

onTap: (){
                  Navigator.pushNamed(context, '/ot1');
                },

but when i created constructor in class CustomListView and passed field i got this error that one argument is missing in this line '/ot1': (context) => CustomListView(),

this is the code of my class CustomListView share below

class CustomListView extends StatelessWidget {
  final List<Spacecraft> spacecrafts;
  CustomListView(this.spacecrafts);

  Widget build(context) {
    return ListView.builder(
      itemCount: spacecrafts.length,
      itemBuilder: (context, int currentIndex) {
        return createViewItem(spacecrafts[currentIndex], context);
      },
    );
  }

I have searched for it for so much and didn't find a solution new to programming and FLUTTER language please HELP

Upvotes: 0

Views: 430

Answers (3)

Ravinder Kumar
Ravinder Kumar

Reputation: 8010

If you want to pass data between screen using pushedName do it like,

 Navigator.pushNamed(
              context, '/ot1', arguments: mFeedData);

and fetch data like,

  @override
  Widget build(BuildContext context) {
    mFeedData = ModalRoute.of(context).settings.arguments;
    ....
  }

if you do not wish to pass any data then remove below portion from your code

CustomListView(this.spacecrafts)

or make it as an optional positional argument,

CustomListView([this.spacecrafts])

What is Positional parameter?

Wrapping a set of function parameters in [] marks them as optional positional parameters:

What is Named parameters?

When calling a function, you can specify named parameters using paramName: value. For example:

enableFlags(bold: true, hidden: false);

When defining a function, use {param1, param2, …} to specify named parameters:

/// Sets the [bold] and [hidden] flags ...
void enableFlags({bool bold, bool hidden}) {...}

Upvotes: 2

Thapelo Radebe
Thapelo Radebe

Reputation: 627

Try adding square brackets [this.spacecrafts] so that the spacecraft argument becomes an optional argument.

class CustomListView extends StatelessWidget {
final List<Spacecraft> spacecrafts;
CustomListView([this.spacecrafts]); # <- this is where you use the brackets
...

Upvotes: 0

Pyth0nGh057
Pyth0nGh057

Reputation: 686

I am using this solution for navigation in my Flutter apps:

class RouteGenerator {
  static Route<dynamic> generateRoute(RouteSettings settings) {
    // Getting arguments passed in while calling Navigator.pushNamed
    final args = settings.arguments;

    switch (settings.name) {
      case '/':
        return MaterialPageRoute(builder: (_) => Home());

      case '/routeWithoutArguments':
        return MaterialPageRoute(
          builder: (_) => PageWithoutArguments(),
        );

      case '/routeWithArguments':
        if (args is String) { // I check if the arguments provided are valids
          return MaterialPageRoute(
            builder: (_) => PageWithArguments(myString: args),
          );
        }
        return _errorRoute();

      default:
        return _errorRoute();
    }
  }

  static Route<dynamic> _errorRoute() {
    return MaterialPageRoute(builder: (_) {
      return Scaffold(
        appBar: AppBar(
          title: Text('Error'),
        ),
        body: Center(
          child: Text('ERROR'),
        ),
      );
    });
  }
}

Then in my widget App:

MaterialApp(
    initialRoute: '/',
    onGenerateRoute: RouteGenerator.generateRoute,
    ...
)

Then to call my routes without arguments:

Navigator.pushNamed(
    context,
    '/routeWithoutArguments',
);

and to call with arguments:

Navigator.pushNamed(
    context,
    '/routeWithArguments',
    arguments: "my argument",
);

I have learn this solution from ResoCoder

Upvotes: 0

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