How can I resolve "The argument type 'String' can't be assigned to the parameter type 'int' " - Flutter

Question

I'm trying to fetch data Online Using HTTP GET with Flutter SDK. I'm trying with this code https://github.com/RaglandCodes/Flutter-basic-API/blob/master/lib/main.dart but it is showing an error about data type that's

The argument type 'String' can't be assigned to the parameter type 'int'

Here's Error part

new Card(
     child: new Container(
     child: new Text(data[index]['name']), //error red underlying with 'name'
     padding: EdgeInsets.all(20),
     ),

Here's my main.dart

import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:flutter/foundation.dart';
import 'package:http/http.dart' as http;
import 'dart:async';

void main() {
  runApp(new MaterialApp(home: new HomePage(),));
}

 class HomePage extends StatefulWidget {
   @override
   _HomePageState createState() => _HomePageState();
 }

 class _HomePageState extends State<HomePage> {

  String url="https://swapi.co/api/people/";
  List<String> data;

  /*onCreate*/
  @override
  void initState() {
    // TODO: implement initState
    super.initState();

    getJSONData(); //method
  }

   @override
   Widget build(BuildContext context) {
     return new Scaffold(
       appBar: AppBar(
           title: Text("my JSON app")
       ),
       body: new ListView.builder(
        // itemCount: 1,
         //itemCount: data==null ? 0 :data.length ,
         itemCount: data == null ? 0 : data.length,

         itemBuilder: (BuildContext context, int index){
           return new Container(
             child: new Center(
               child: new Column(
                 crossAxisAlignment: CrossAxisAlignment.stretch, 
                 children: <Widget>[
                   new Card(
                     child: new Container(
                       child: new Text(data[index]['name']),
                       padding: EdgeInsets.all(20),
                     ),
                   )
                 ],
               ),
             ),
           );
         },
       ),
     );
   }

   /*method*/ //RT is Future<String>
  Future<String> getJSONData() async{
    var response =await http.get(
      Uri.encodeFull(url),
      headers: {"Accept": "application/json"}
    );
   print(response.body);
   debugPrint(response.body);

    setState(() {
      var convertDataToJson= json.decode(response.body);
      data=convertDataToJson['results'];
    });

    return "Success";
  }
 }

Solution 1

You have to set data variable to List type.

That's should work:

import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:flutter/foundation.dart';
import 'package:http/http.dart' as http;
import 'dart:async';

void main() {
  runApp(new MaterialApp(
    home: new HomePage(),
  ));
}

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  String url = "https://swapi.co/api/people/";
  List data;

  /*onCreate*/
  @override
  void initState() {
    // TODO: implement initState
    super.initState();

    getJSONData(); //method
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: AppBar(title: Text("my JSON app")),
      body: new ListView.builder(
        // itemCount: 1,
        //itemCount: data==null ? 0 :data.length ,
        itemCount: data == null ? 0 : data.length,

        itemBuilder: (BuildContext context, int index) {
          return new Container(
            child: new Center(
              child: new Column(
                crossAxisAlignment: CrossAxisAlignment.stretch,
                children: <Widget>[
                  new Card(
                    child: new Container(
                      child: new Text(data[index]['name'] ?? ''),
                      padding: EdgeInsets.all(20),
                    ),
                  )
                ],
              ),
            ),
          );
        },
      ),
    );
  }

  /*method*/ //RT is Future<String>
  Future<String> getJSONData() async {
    var response = await http
        .get(Uri.encodeFull(url), headers: {"Accept": "application/json"});
    print(response.body);
    debugPrint(response.body);

    setState(() {
      var convertDataToJson = json.decode(response.body);
      data = convertDataToJson['results'];
    });

    return "Success";
  }
}

Solution 2

That's worked for me

http.get(Uri.https('https://swapi.co', 'api/people'));

or

http.get(Uri.parse('https://swapi.co/api/people'));

Solution 3

If you add .toString() the error will disappear:

Text(data[index]['name'].toString())

good

Solution 4

The reason is that http.get can't work with strings anymore. You need to use Uri to parse the HTTP address.

I had the same issue which I fixed it with this approach:

var url = Uri.parse("https://your_api_link");

then call it like this (attaching the http):

http.Response response = await http.get(url);

This should work.

Solution 5

var response = await http.get(Uri.parse(url));

View more solutions

Comments

[jamesdlin]

data is of type List<String>. What is data[index]['name'] supposed to be?

[jamesdlin]

int.parse('name') is not going to help here.

[Michel Feinstein]

This answer would be more complete if you explained why

[Michael Hathi]

This is a valid answer for those using http: 0.13.0 and above. Here is the changelog which mentions this as a breaking change: pub.dev/packages/http/changelog#0130-nullsafety0

[PuNeet Pal]

The argument type 'String' can't be assigned to the parameter type 'Uri'.

[Syscall]

Thank you for this code snippet, which might provide some limited, immediate help. A proper explanation would greatly improve its long-term value by showing why this is a good solution to the problem and would make it more useful to future readers with other, similar questions. Please edit your answer to add some explanation, including the assumptions you’ve made.

[umekalu]

Well, I don't really know the reason, maybe String could no longer handle URL values due to the async pattern in retrieving the url data. But I think someone else could have a better reason here.

[ZygD]

Such answer already exists

[Chris]

Welcome to Stack Overflow. Code is a lot more helpful when it is accompanied by an explanation. Stack Overflow is about learning, not providing snippets to blindly copy and paste. Please edit your question and explain how it answers the specific question being asked. See How to Answer.

[Chris]

Also, this question is nearly 3 years old and already has 13 answers, including an accepted answer and an answer with a score of over 60. Are you certain this answer brings something new and improved? If so, please edit it to explain how it improves upon what's already here.