Type 'String' is not a subtype of type 'Null' in get method flutter

Question

I got this error:

type 'String' is not a subtype of type 'Null' in get method flutter

This is the get API function that I use:

 Future<Stream<ServiceTypes>> getServiceTypesa() async {
 final String url = 'https://test.com';

 final client = new http.Client();
 final streamedRest = await client.send(
   http.Request('get', Uri.parse(url))
 );

 return streamedRest.stream 
     .transform(utf8.decoder)
     .transform(json.decoder)
     .expand((data) => (data as List))
     .map((data) => ServiceTypes.fromJson(data));
}

You can see here the function detect the data:

I saw also this error:

StateError (Bad state: Stream has already been listened to.)

and this error:

This is my listen function:

  @override
  void initState() {
    _serviceTypes = new List<ServiceTypes>();
    listenForServiceTypes();
    super.initState();
  }

  void listenForServiceTypes() async {
    setState(() {
      this._show_serviceTypesProgress = true;
    });
    final Stream<ServiceTypes> stream = await getServiceTypesa();

    stream.listen((ServiceTypes serviceTypes) =>
        setState(() => _serviceTypes.add(serviceTypes)));

    setState(() {
      this._show_serviceTypesProgress = false;
    });

    print(_serviceTypes);
  }

This is the model that T made:

I don't know what is the problem because the print function return : []

Are you sure the 'deleted_at' is inside the json from your api server? — Daniel Oliveira
– Daniel Oliveira, Commented Jan 28, 2020 at 18:52
@securisec it was long time i forget what was install in my VS code — Abdullah
– Abdullah, Commented Oct 8, 2023 at 11:06

Avinash · Accepted Answer · 2020-01-29 11:04:26Z

18

When you create model, the image type value is null so, the model is create with Null type of image but when images are not null type from server then it gives you an error

     type 'String' is not a subtype of type 'Null' in get method flutter

because your image type is String from server and you get value by Null Object, So use String type object for getting string value or images.

Use this

  Class ServiceTypes{
  String image;

instead of

   Class ServiceTypes{
   Null image;

answered Jan 29, 2020 at 11:04

Avinash

8974 silver badges11 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Abdelkhalek Haddany · Accepted Answer · 2022-03-27 15:53:06Z

10

As extra information, you can check the keys name. I faced the same problem just because I tried to fetch a key not found.

In the first time I wrote content instead of details and in my API I have details not content.

have a good day :)

edited Mar 27, 2022 at 15:53

user12035742

answered Mar 22, 2022 at 12:28

Abdelkhalek Haddany

4831 gold badge5 silver badges15 bronze badges

Comments

Mohamed Sayed · Accepted Answer · 2020-01-29 10:26:15Z

5

The issue is clear, you define image type as Null then trying to pass string to it, try to change definition.. like so:

Class ServiceTypes{
  int id;
  String name;
  String image;
...

answered Jan 29, 2020 at 10:26

Mohamed Sayed

8515 silver badges15 bronze badges

Comments

Gurjeet Singh · Accepted Answer · 2022-03-22 18:49:27Z

2

use ? this for nullable key. For example :

final String? title; final String? category;

here is the complete solution : Is it possible to parse json in Flutter/Dart with missing attributes (keys of json data)?

answered Mar 22, 2022 at 18:49

Gurjeet Singh

411 silver badge10 bronze badges

Comments

Parviz Hashimi · Accepted Answer · 2023-05-09 16:47:22Z

1

Step 1: late String? urlToImage; You add '?'

Step 2: urlToImage: json['urlToImage'].toString(),

answered May 9, 2023 at 16:47

Parviz Hashimi

213 bronze badges

Comments

user23090323 · Accepted Answer · 2023-12-12 21:59:44Z

0

This kind of error occurs when you create model with pure datatype. In model you give the type to any property such as string,int or any other data-type but assigning it a nullable value. The program through exception that you are assigning a nullable value to non-nullable variable. I have gone through these kind of error in flutter when mapping the firebase data to my model.

answered Dec 12, 2023 at 21:59

user23090323

1

1 Comment

Ilya Khrustalev Over a year ago

Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.

Anoopkumar · Accepted Answer · 2023-05-27 07:01:05Z

-1

To Convert type toString Eg: Text(jsonList['name].toString());

answered May 27, 2023 at 7:01

Anoopkumar

11 bronze badge

1 Comment

Community Over a year ago

As it’s currently written, your answer is unclear. Please edit to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers in the help center.

Collectives™ on Stack Overflow

Type 'String' is not a subtype of type 'Null' in get method flutter

7 Answers 7

Comments

Comments

Comments

Comments

Comments

1 Comment

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

7 Answers 7

Comments

Comments

Comments

Comments

Comments

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related