The operator '[]' isn't defined for the type 'Iterable<Meal>'. Try defining the operator '[]'.dartundefined_operator

Question

im trying return constractor of the class MealItem inside another widget in another class i did the import correctly and i got this

Error : The operator '[]' isn't defined for the type 'Iterable'. Try defining the operator '[]'.dartundefined_operator

Here the MealItem class

import 'package:flutter/material.dart';
import '../models/meal.dart';

class MealItem extends StatelessWidget {
  final String title;
  final String imageUrl;
  final int duration;
  final Complexity complexity;
  final Affordability affordability;

  MealItem(
      this.title,
      this.imageUrl,
      this.duration,
      this.complexity,
      this.affordability
    );
  }
}

Here is the Error in the CategoryMealsScreen class

import 'package:flutter/material.dart';
import '../widgets/meal_item.dart';
import '../models/dummy_data.dart';

class CategoryMealsScreen extends StatelessWidget {
  static const routeName = '/CategoriesScreen';

  //final String categoryId;
  //final String categoryTitle;

  //CategoryMealsScreen(this.categoryId,this.categoryTitle);

  @override
  Widget build(BuildContext context) {
    final routeArgs =
        ModalRoute.of(context).settings.arguments as Map<String, String>;
    final categoryTitle = routeArgs['title'];
    final categoryId = routeArgs['id'];
    final categoryMeals = DUMMY_MEALS.where((meal) {
      return meal.categories.contains(categoryId);
    });
    return Scaffold(
      appBar: AppBar(title: Text(categoryTitle)),
      body: ListView.builder(
        itemBuilder: (ctx, index) {
          return MealItem(
              title : categoryMeals[index].title,
              imageUrl: categoryMeals[index].imageUrl,
              duration: categoryMeals[index].duration,
              complexity: categoryMeals[index].complexity,
              affordability: categoryMeals[index].affordability
           );
        },
        itemCount: categoryMeals.length,
      ),
    );
  }
}

here is the IDE errors using vsCode :

The operator '[]' isn't defined for the type 'Iterable<Meal>'.
Try defining the operator '[]'.

any Help will be appreciated

Answer 1

You are passing named arguments to a constructor that takes positional arguments instead.

Change:

import 'package:flutter/material.dart';
import '../models/meal.dart';

class MealItem extends StatelessWidget {
  final String title;
  final String imageUrl;
  final int duration;
  final Complexity complexity;
  final Affordability affordability;

  // use parenthesis '{}' to wrap the constructor arguments to make them named arguments
  MealItem({
      this.title,
      this.imageUrl,
      this.duration,
      this.complexity,
      this.affordability
    });
  }
}

or simply remove the names and pass positional arguments when creating the MealItem

Also: Positional arguments are required by default, but named arguments are not. After changing them to named arguments, don't forget to mark them as @required if you need

Also use toList() here:

final categoryMeals = DUMMY_MEALS.where((meal) {
  return meal.categories.contains(categoryId);
}).toList();