i cannot solve this error. Flutter - rest api

Question

/* The method '[]' can't be unconditionally invoked because the receiver can be 'null'. Try making the call conditional (using '?.') or adding a null check to the target ('!').*/

import 'dart:core';

import 'package:flutter/material.dart';

import 'package:rest_api/data/fetch_data.dart';

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

  @override
  State<MyWidget> createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  int index =0;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: FutureBuilder(
        future: getPost(),
        builder: (context, snapshot) {
          
          return ListView.builder(
            
            itemBuilder: (context,index){
              return Text(snapshot.**data[index]**); 
            });
        })
        
        );
  
  }
}

See: https://stackoverflow.com/questions/64278595/null-check-operator-used-on-a-null-value/67990442#67990442 — Richard Heap, Jul 29 '22 at 21:45
What is your model class , Can you include that as well, Also paste as code-snippet instead of code-image — Md. Yeasin Sheikh, Jul 29 '22 at 21:54

Jacob Miller · Answer 1 · 2022-07-29T21:40:49.887

0

The API might not give the proper response so the part of it you are trying to read might be null or non existent and Flutter has no way of knowing that the API will return a string. Try a default value if it's null like this Text(res.body.text ?? "Default")

edited Jul 29 '22 at 21:40

answered Jul 29 '22 at 21:37

Jacob Miller

562
4
16

i uploaded photo – Unudulmayan melodiyalar Jul 29 '22 at 21:39
That's not allowed. – Jacob Miller Jul 29 '22 at 21:40
You must paste formatted code. – Jacob Miller Jul 29 '22 at 21:53

score 0 · Answer 2 · answered Jul 29 '22 at 21:43

0

Try adding an exclamation mark (!):

return Text(snapshot.data![index]);

or:

return Text(snapshot.data[index] ?? "Data is null");

answered Jul 29 '22 at 21:43

Hama Sabah

342
4
9

i checked.dont work – Unudulmayan melodiyalar Jul 29 '22 at 21:50
Ok but what data you want to retreive? could you show your firestore data. – Hama Sabah Jul 29 '22 at 21:53
its not firebase. i want to get information from rest api – Unudulmayan melodiyalar Jul 29 '22 at 21:57

score 0 · Answer 3 · answered Jul 29 '22 at 22:06

You can have error from API or getting null/empty data. Check this Demo widget and configure your case. Also, the current is object is not detecting and possible to get null from. You can do.

I gues the for your case it will be

Text(snapshot.data?[index]?? "default");

Follow the snippet and make changes

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

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  late final Future<List<int>?> myFuture;
  @override
  void initState() {
    super.initState();
    myFuture = getCatData();
  }

  Future<List<int>?> getCatData() async {
    await Future.delayed(Duration(seconds: 2));
    //your operations
    return [1, 2, 5];
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButton: FloatingActionButton(onPressed: () {
        setState(() {});
      }),
      body: FutureBuilder<List<int>?>(
        future: myFuture,
        builder: (context, AsyncSnapshot snapshot) {
          if (snapshot.connectionState == ConnectionState.waiting) {
            return const CircularProgressIndicator();
          }
          if (snapshot.hasError) {
            return Text("Error ${snapshot.error}");
          }
          if (!snapshot.hasData) {
            return Text("no Data found");
          }
          if (snapshot.data!.isEmpty) {
            return Text("Empty found");
          }

          if (snapshot.hasData) {
            return ListView.builder(
              itemCount: snapshot.data.length,
              itemBuilder: (context, index) {
                return Container(child: Text(snapshot.data[index].toString()));
              },
            );
          }

          return Text("NA");
        },
      ),
    );
  }
}

i cannot solve this error. Flutter - rest api

3 Answers3