This is the case for List in my StatefulWidget

Question

Flutter

import 'package:country_house/pages/Country.dart';
import 'package:dio/dio.dart';
import 'package:flutter/material.dart';

class AllCountries extends StatefulWidget {
  const AllCountries({Key? key}) : super(key: key);

  @override
  State<AllCountries> createState() => _AllCountriesState();
}

class _AllCountriesState extends State<AllCountries> {
  Future<List> countries=[];
  Future<List> getCountries() async {
    var response = await Dio().get('https://restcountries.com/v3.1/all');
    return response.data.length;
  }

  @override
  void initState() {
    countries = getCountries();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    getCountries();
    return Scaffold(
      appBar: AppBar(
        title: Text('All Countries'),
        centerTitle: true,
      ),
      body: Container(
        child: Padding(
          padding: const EdgeInsets.all(10.0),
          child: FutureBuilder<List>(
              future: countries,
              builder: (BuildContext context, AsyncSnapshot<List> snapshot) {
                if (snapshot.hasData) {
                  return Text('hello');
                }
                return null;
              }),
          
        ),
      ),
    );
  }
}

I get the following error: A value of type 'List' can't be assigned to a variable of type 'Future<List>'.

• 'List' is from 'dart:core'.
• 'Future' is from 'dart:async'. Future countries=[];

How can I resolve this issue?

Answer 1

You have to declare countries as a late Future:

late Future<List> countries;

then, the initState() will work. Note that you are requesting the length of the response and not the data. In order to populate the list you should also parse the jSon data. You can read an example of networking in flutter using Dio at the following link: Networking in Flutter using Dio

Answer 2

You have to declare countries in this form:
Future<List> countries = Future.value([]);

class _AllCountriesState extends State<AllCountries> {
  Future<List> countries = Future.value([]);
  Future<List> getCountries() async {
    var response = await Dio().get('https://restcountries.com/v2/all');
    return response.data;
  }

  @override
  void initState() {
    countries = getCountries();
    super.initState();
  }