CODEWITHSUNDEEP
flutterdart
Nz Mumbere
Nz Mumbere

Reputation: 19

_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'List<dynamic>

How do I go about fixing this issue cause I have tried all the solutions:

[ERROR:flutter/runtime/dart_vm_initializer.cc(39)] Unhandled Exception: type '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'List'

late String selectedDestination = '';
late List destinationsList = [];
var isLoaded = false;

Future getAllDestinations() async {
  String urlDestinations = "http://localhost/api/destinations/";
  var response = await http.get(Uri.parse(urlDestinations));
  if(response.statusCode == 200){
    var jsonData = json.decode(response.body);
    setState((){
      destinationsList = jsonData;
    });
  }
  print(destinationsList);
}

An the DropDown code is this type here

DropdownButtonFormField(
  decoration: InputDecoration(
    prefixIcon: const Icon(
      Icons.location_pin,
      color: primary,
    ),
    border: OutlineInputBorder(
      borderRadius: BorderRadius.circular(10),
    ),
    label: const Text(
      "Destination to *",
      style: TextStyle(
        fontSize: 16,
        color: primary,
      ),
    ),
  ),
  validator: (value) => value == null
      ? 'Field must not be empty'
      : null,
  isExpanded: true,
  value: selectedDestination,
  items: destinationsList.map((item) {
    return DropdownMenuItem(
      value: item['id'].toString(),
      child:
          Text(Text(item['name']).toString()),
    );
  }).toList(),
  onChanged: (String? value) {
    setState(() {
      selectedDestination = value!;
    });
  },
)`

Sample API

{
    "destinations": [
        {
            "id": 1,
            "name": "Nairobi",
            "city": "Nairobi",
            "location": null,
            "mobile": "0741761232",
            "status": 1,
            "created_at": "2022-10-24T11:57:51.000000Z",
            "updated_at": "2022-10-24T11:57:51.000000Z"
        },
        {
            "id": 2,
            "name": "Voi",
            "city": "Voi",
            "location": null,
            "mobile": "0741761235",
            "status": 1,
            "created_at": "2022-10-24T11:58:05.000000Z",
            "updated_at": "2022-10-24T11:58:05.000000Z"
        },
}

I just need to fetch the name. I am expecting to fetch a list of items in the dropdown.

Upvotes: 0

Views: 79

Answers (1)

Krish Bhanushali
Krish Bhanushali

Reputation: 2007

The reason is you are directly assigning a map to a list when you are decoding the json. Idle way to do a json deserialization should be done using Model Classes. Example: https://docs.flutter.dev/cookbook/networking/fetch-data

To solve your problem you can do:

if(response.statusCode == 200){
    var jsonData = json.decode(response.body);
    setState((){
      destinationsList = jsonData["destinations"];
    });

You need to access the key which has list to assign it to the list of destinations. Like this jsonData["destinations"];

Upvotes: 3

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