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";
  }
 }

Polymerous

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

Answer 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";
  }
}

Mcafee

This answer would be more complete if you explained why – Olives

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

Answer 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'));

Sacerdotal

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 – Chrystalchryste

Answer 3

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

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

good

Linkage

Answer 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.

Pufahl

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. – Pufahl

Answer 5

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

Hoelscher

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. – Seyler

Answer 6

That's worked for me

 http.Response respobse= await 
      http.get(Uri.parse("https://jsonplaceholder.typicode.com/photos"));
    
    Uri.parse(json Url);

use this.

Charlot

Answer 7

This one will work

String url = '$api?lat=$latitude&lon=$longitude&APPID=$appId';
 http.Response response = await http.get(Uri.parse(url));

Mendelssohn

Answer 8

if you will simply add .toSting() to your lists like below it will remove the error.

new Card(
     child: new Container(
     child: new Text(data[index]['name'].toString()), //This line
     padding: EdgeInsets.all(20),
),

Usance

Such answer already exists – Sacker

Answer 9

That's worked for me

void getData() async {
  Response response = await 
  http.get(Uri.parse("https://jsonplaceholder.typicode.com/todos/1"));
  print(response.body);
}

Triazine

Answer 10

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

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

So:

new Card(
     child: new Container(
     child: new Text(data[index]['name'].toString()), //you'll no longer get an error
     padding: EdgeInsets.all(20),
     ),

Lm

Answer 11

u can use this way

Future<http.Response> fetchAlbum() {return http.get(Uri.https('jsonplaceholder.typicode.com', 'albums/1'));}

Baldwin

Answer 12

if you are using pdf package your want to delete import 'dart:html'; and use import 'dart:io';
It's worked for me, Have a good day :-)

Fusain

Answer 13

Future<String> getSWData() async 
{

   // String res = await http.get(Uri.encodeFull(url), headers: {"Accept": "application/json"});
    http.Response res = await http.get(url);

     // var res =   await http.get(Uri.https('http://3.255.7.222:8084/sipService/supplerMaster/v1/getSupplierMasterList', 'api/people'));

    var resBody = json.decode(res.body);
    setState(() {
      data = resBody;
    });
    print(resBody);
    return "Sucess";
  }

Denaedenarius