RangeError (index): Invalid value: Valid value range is empty: 0

Question

Widget build(context) {
    try{
      if (isFirst == true) {
        fetchImage();
        fetchCategories(context);
        isFirst = false;
      }
    }catch(Excepti         


        

Answer 1

Make sure specifying the length of the list of data. For example, if you're using ListView.builder give proper value to the attribute itemCount.

ListView.builder(
            itemCount: snapshot.data.length,
            itemBuilder: (ctx, index) {
              return WidgetItem();
            });

Answer 2

The problem can be that you are trying to access a variable/array that is not ready yet (maybe because the future/api call is not finished)

A quick workaround could be to check the length of the array or check for null, example:

Text( (myArray?.length > 0 ? myArray[0] : '') );

Answer 3

I assume you getting data from fetch ApI method, If you are getting data in fetchApI metod. then you should follow this

fetchApI and is asynchronous method so it takes time to get data from json and in the begging fetchApI is empty, so it gives error of range. you can make fetchApI method asynchronous using await and async* and while calling that method use .then method and then access values.

fetchApI().then((){ // access fetchApI over here });

Answer 4

There are quick-and-dirty answer, and proper answer

Quick-and-dirty

Use list?.elementAt(<index>) ?? "" for safe access to element of a list

Widget build(context) {
    try{
      if (isFirst == true) {
        fetchImage();
        fetchCategories(context);
        isFirst = false;
      }
    }catch(Exception){

    }

    return MaterialApp(
      home: Scaffold(
        backgroundColor: Colors.black,
        appBar: AppBar(
          title: Text('Lets see images!'),
        ),
        body: new Column(
          children: <Widget>[
            new Row(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                new InkResponse(
                    child: new Column(
                      children: <Widget>[
                        Padding(
                          padding: EdgeInsets.all(10.0),
                          child: new Image.asset(
                            catimages?.elementAt(0) ?? "",
                            width: 60.0,
                            height: 60.0,
                          ),
                        ),
                        new Text(
                          categoriesText?.elementAt(0) ?? "",
                          style: TextStyle(color: Colors.white),
                        ),
                      ],
                    ),
                    onTap: () {
                      debugPrint("on tv clikced");
                      widget.fetchApI.fetchSubCategories(context, 6);
                    }),
                new InkResponse(
                  child: new Column(
                    children: <Widget>[
                      Padding(
                        padding: EdgeInsets.all(10.0),
                        child: new Image.asset(
                          catimages?.elementAt(1) ?? "",
                          width: 60.0,
                          height: 60.0,
                        ),
                      ),
                      new Text(
                        categoriesText?.elementAt(1) ?? "",
                        style: TextStyle(color: Colors.white),
                      ),
                    ],
                  ),
                  onTap: () {
                    debugPrint("on moview clicked");
                    widget. fetchApI.fetchSubCategories(context, 7);
                  },
                ),
                new InkResponse(
                  child: new Column(
                    children: <Widget>[
                      Padding(
                        padding: EdgeInsets.all(10.0),
                        child: new Image.asset(
                          catimages?.elementAt(2) ?? "",
                          width: 60.0,
                          height: 60.0,
                        ),
                      ),
                      new Text(
                       categoriesText?.elementAt(2) ?? "",
                        style: TextStyle(color: Colors.white),
                      ),
                    ],
                  ),
                  onTap: () {
                    debugPrint("on news clicked");
                    widget.fetchApI.fetchSubCategories(context, 10);
                  },
                ),
                new InkResponse(
                  child: new Column(
                    children: <Widget>[
                      Padding(
                        padding: EdgeInsets.all(10.0),
                        child: new Image.asset(catimages?.elementAt(3) ?? "",
                            width: 60.0, height: 60.0),
                      ),
                      new Text(
                        categoriesText?.elementAt(3) ?? "",
                        style: TextStyle(color: Colors.white),
                      ),
                    ],
                  ),
                  onTap: () {
                    debugPrint('on shows clicked');
                    widget.fetchApI.fetchSubCategories(context, 8);
                  },
                ),
                new InkResponse(
                  child: new Column(
                    children: <Widget>[
                      Padding(
                        padding: EdgeInsets.all(10.0),
                        child: new Image.asset('assets/live_icon.png',
                            width: 60.0, height: 60.0),
                      ),
                      new Text(
                        'Live',
                        style: TextStyle(color: Colors.white),
                      ),
                    ],
                  ),
                  onTap: () {
                    debugPrint('on live clicked');
                  },
                ),
              ],
            ),
            ImageList(images,widget.fetchApI),
          ],
        ),
      ),
    );
  }
}

Proper answer

Frankly, if I were to review this code, even if it works seamlessly, I would reject this change, because of the structure/pattern this code is using is quite bad.

Please use FutureBuilder, StreamBuilder or ValueListenableBuilder instead, but you need to provide more code (especially fetchImage and fetchCategories) for us to help.

Answer 5

In case the other methods don't work, check if your database contains any conflicting data entries. If so, fix them.

Answer 6

To me, going to the project directory and running the command flutter clean fixed the error