CODEWITHSUNDEEP
dartflutter
Zuhair Ali
Zuhair Ali

Reputation: 627

Flutter - Iterate through object keys and values

I have and object and I wondering if there is a simple way to iterate through it keys and values?

class Post {
  String id;
  String title;
  String article;

  Post(
      {
        this.id,
        this.title,
        this.article
      }
      );
}

Upvotes: 26

Views: 40477

Answers (5)

Rajat Upadhyay
Rajat Upadhyay

Reputation: 168

It's incredibly weird that there are no simple answers to this easy question.

for (var key in yourObject.keys)
  Text("${key}: ${yourObject[key]}"),

Upvotes: 4

8zeros
8zeros

Reputation: 31

You could also use a getter? It will require you to set up all of the fields once, but after that, you can call the complete list of fields and iterate through that.

class Person{
  final String _firstName;
  final String _secondName;
  Person(this._firstName,this._secondName);

  String get hisName{
    return _firstName;
  }
}


class Player extends Person{

  final int _shirtNumber;

  Player(String _firstName,String _secondName,this._shirtNumber) : super(_firstName, _secondName);

  List get everything{
    final stuff=[_firstName,_secondName,_shirtNumber];

    return stuff;
  }
}


void main(List<String> arguments) {

  final foo = Player('David','Beckham',7);

  print(foo.everything);
  
  for (final blah in foo.everything){
    print(blah);
  }
}

Upvotes: 3

Mike Mitterer
Mike Mitterer

Reputation: 7180

This bugs me almost every day. It's also a problem on the web-side of Dart. In my opinion this is one of the major shortcomings of Dart...

However - here is my solution. I'm using a interface class for these "serializable" classes. 

abstract class JsonTO {
    Map<String, dynamic> toJson();
}

class Device implements JsonTO {
    Map<String, dynamic> toJson() {
        return ... Your serialization thing
    }  
}

main() {
    final device = Device();
    final json = device.toJson();

    json.forEach((final String key, final value) {
        _logger.info("Key: {{$key}} -> value: ${value}");
        // do with this info whatever you want
    }); 
}

Upvotes: 15

lrn
lrn

Reputation: 71683

There is not.

What you are asking for is reflection. You can use the dart:mirrors API for that, if the library is available on your platform (it's not in Flutter). You might be able to generate code for it by using package:reflectable. Or you can use package:json_serializable to generate a Map from an object.

If you are just trying to do something for one particular class, I'd just manually write: dart Map<String, dynamic> toJson() => {"id": id, "title": title, "article": article}; and then use that when you want to iterate.

Upvotes: 19

Touqeer Aslam
Touqeer Aslam

Reputation: 220

All you have to do the name the object in which you have all properties e.g

var object = { this.id,
        this.title,
        this.article   }
for (var property in object) {
    if (object.hasOwnProperty(property)) {
        // do stuff
    }
}

Upvotes: -3

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