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List<Model> prints Instance of 'Model' flutter

i want to a list of string to show in a dropdown, but i am not able to do that. i have a list named categories, i am initializing it with some data, i want to access it something like "categories.CategoryName" or "categories.SubCategories[0]"

i am declaring a list as

List<categoryListModel> categories = [
  categoryListModel(
    CategoryName: 'Print Design',
    SubCategories: [
      'Brochers',
      'Flyers',
      'Posters',
      'Business Cards',
      'Packaging',
      'Stationery'
    ],
  ),
  categoryListModel(
    CategoryName: 'Digital Design',
    SubCategories: [
      'Web Design',
      'App Design',
      'Social Media Graphics',
      'Email Templates',
      'Banner Ads',
      'Infographics'
    ],
  ),];

and my model is

class categoryListModel {
  String CategoryName;
  List<String> SubCategories;

  categoryListModel({
    required this.CategoryName,
    required this.SubCategories,
  });
}

when i print category
it prints

I/flutter (10525): [Instance of 'categoryListModel', Instance of 'categoryListModel', Instance of 'categoryListModel', Instance of 'categoryListModel', Instance of 'categoryListModel', Instance of 'categoryListModel', Instance of 'categoryListModel', Instance of 'categoryListModel', Instance of 'categoryListModel', Instance of 'categoryListModel']
Tags:

3

Answers


  1. 0

    Instead of

    print(categories);

    try:

    print(categories.map((e) => e.CategoryName).toList());
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  2. 0

    What happened…

    Looks like you tried to call print like this:

    print(categories);

    In this case categories is a list.
    All classes in dart has default toString implementation. Same with List implementations.

    Which means, that it will print a list of items it contains, calling toString for each item.

    How to fix

    In order to customize how categoryListModel instances are printed you got to override toString, e.g.:

    class categoryListModel {
// ...
  @override
  String toString() => CategoryName;
}

    In this case print(categories) will emit smth like this:

    [Print Design, Digital Design]

    Then if you want to make list to print something different from just list of inner items, then looks like you should either implement your own version of List or create a wrapper:

    class CategoriesList {
  List<categoryListModel> list;
  CategoriesList(this.list);
  @override
  String toString() {
    // do whatever you want it to print
    return "Categories list is:" + list.toString();
  }
}

// ...
void main() { print(categories); }
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  3. 0

    In Dart newly created class will be print as Instance of ClassName. If you want to modify the value which is printing, then you have to override the toString() method in the categoryListModel class.

    class Person
{
  final String name;

  Person({required this.name});

  @override
  String toString() {
    return 'Person name is: $name';
  }
}

    Then if we call

    void main() {
  Person person = Person(name: 'Flutter');
  print(person);
}

    Output:

    Person name is: Flutter
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