CODEWITHSUNDEEP
listflutterdartcasting
frax
frax

Reputation: 153

How to access instance method from inside of a list?

So, I'm trying to group sort a list by a particular method of an class. My code currently stores "meals" with Hive by this class format:

https://pub.dev/packages/hive

import 'package:hive/hive.dart';

part 'meal.g.dart';

@HiveType(typeId: 1, adapterName: "MealAdapter")
class MealModel{
  @HiveField(0)
  int id;
  @HiveField(1)
  String mealName;
  @HiveField(2)
  int calories;
  @HiveField(3)
  int carbohydrates;
  @HiveField(4)
  int protein;
  @HiveField(5)
  int fats;
  @HiveField(6)
  String day;

  MealModel(this.id, this.mealName, this.calories, this.day, [this.carbohydrates, this.protein, this.fats]);
}

The problem is when I have no idea I would pass values to each of the parameters for a GroupedListView (https://pub.dev/packages/grouped_list) to display the stored meals:

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:hive/hive.dart';
import 'package:jaetrack/colors.dart';
import 'package:jaetrack/dbmodel/meal.dart';
import 'package:hive_flutter/hive_flutter.dart';
import 'package:grouped_list/grouped_list.dart';

class Meals extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return MealsState();
  }
}

class MealsState extends State<Meals> {
  Box<MealModel> mealBox = Hive.box<MealModel>('meals');
  MealModel previousMeal;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: mainPurp,
      body: SingleChildScrollView(
        child: Column(
          children: [
            ValueListenableBuilder(
                valueListenable: Hive.box<MealModel>('meals').listenable(),
                builder: (context, Box<MealModel> box, _) {
                  final mealList = box.values.toList().cast<MealModel>();
                  print(mealList);
                  return GroupedListView<dynamic, String>(
                    elements: mealList,
                    groupBy: (meal) => meal, // no idea how to sort by calories, name etc. of my MealModel class,
                    groupSeparatorBuilder: (String groupByValue) =>
                        Text(groupByValue), // date value
                    itemBuilder: (context, dynamic element) =>
                        Text(element['name']), // this is where I would put the meal names/calories etc.
                    itemComparator: (item1, item2) =>
                        item1['name'].compareTo(item2['name']), // sort by date is what I'm looking for but again I don't know how to access
                    useStickyGroupSeparators: true,
                    floatingHeader: true,
                    order: GroupedListOrder.ASC,
                  );
                })
          ],
        ),
      ),
    );
  }
}

So if I still don't make sense, I cast the values of my hive box of meals as instances of the MealModel above. So the list would be like [Instance of MealModel, Instance of MealModel, ...] I just need to know how to access the values inside of the instance of the MealModel to pass to the GroupedList.

Upvotes: 0

Views: 153

Answers (1)

Benoit Jadinon
Benoit Jadinon

Reputation: 1161

package:grouped_list library are using dynamic in all of their examples to simplify usage for people who don't get generics. but it's misleading in your case, you're losing the strong typing.

cast to

return GroupedListView<MealModel, String>(

instead of

return GroupedListView<dynamic, String>(

then all of your element, meal and item2 vars will be of MealModel and you can do element.mealName, and meal.calories to group by calories

for the sorting question, simply sort mealList before passing it to the GroupedListView

Upvotes: 1

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