ios – Res is coming again as a null worth, undecided why (Null verify operator used on a null worth)

at any time when I run my program, an exeption happens the place res comes again as null. This system profitable uploads to firebase, and the enter worth is not empty, so I am undecided why the worth does not come again as something.

Right here is the code concerned.

The road occus on this line of the _onPublish Perform, “builder: (context) => NewsPostPage(newsPostId: res!)));”, and it reads, “_CastError (Null verify operator used on a null worth)”

When a button is pressed, it calls operate _onPublish

_onPublish() async {
    if (_formKey.currentState!.validate()) {
      setState(() {
        _isLoading = true;
      });

      await DatabaseService()
          .saveNewsPost(
              _titleEditingController.textual content, _contentEditingController.textual content)
          .then((res) async {
        Navigator.of(context).pushReplacement(MaterialPageRoute(
            builder: (context) => NewsPostPage(newsPostId: res!)));
        _isLoading = true;
        print("Submit Uploaded to Firebase");
      });
    }
  }

Right here is operate Database Service.saveNewsPost()

Future saveNewsPost(
    String title,
    String content material,
  ) async {
    DocumentReference newsPostsRef =
        await FirebaseFirestore.occasion.assortment('newsPosts').add({
      'newsPostId': '',
      'newsPostTitle': title,
      'newsPostTitleArray': title.toLowerCase().break up(" "),
      //'newsPostAuthor': creator,
      'newsPostContent': content material,
      'createdAt': new DateTime.now(),
      'date': DateFormat.yMMMd('en_US').format(DateTime.now())
    });

    await newsPostsRef.replace({'newsPostId': newsPostsRef.id});
//return
    newsPostsRef.id;
  }

Lastly, right here is NewsPostPage

class NewsPostPage extends StatefulWidget {
  last String newsPostId;
  //last String authorName;
  NewsPostPage({
    required this.newsPostId,
    /*required this.authorName*/
  });

  @override
  _NewsPostPageState createState() => _NewsPostPageState();
}

class _NewsPostPageState extends State<NewsPostPage> {
  newsPostDetails NewsPostDetails = newsPostDetails();
  bool _isLoading = true;
  String _error="";
  TextEditingController _fullNameEditingController =
      new TextEditingController();
  TextEditingController _emailEditingController = new TextEditingController();

  late DocumentReference newsPostRef;
  late DocumentSnapshot newsPostSnap;
  

  @override
  void initState() {
    tremendous.initState();
    _getNewsPostDetails;
  }

  _getNewsPostDetails() async {
    await DatabaseService().getNewsPostDetails(widget.newsPostId).then((res) {
      setState(() {
        NewsPostDetails = res;
        _isLoading = false;
      });
    });

    newsPostRef = FirebaseFirestore.occasion
        .assortment('blogPosts')
        .doc(widget.newsPostId);
    newsPostSnap = await newsPostRef.get();

    print(newsPostSnap.information);
  }

  @override
  Widget construct(BuildContext context) {
    return _isLoading
        ? Loading()
        : Scaffold(
            appBar: AppBar(
              elevation: 0.0,
              title: Textual content(NewsPostDetails.newsPostTitle! as String),
            ),
            physique: Heart(
              baby: ListView(
                  padding:
                      EdgeInsets.symmetric(horizontal: 20.0, vertical: 50.0),
                  kids: <Widget>[
                    Text(NewsPostDetails.newsPostTitle as String,
                        style: TextStyle(
                            fontSize: 40.0,
                            color: Colors.black,
                            fontWeight: FontWeight.bold)),
                    SizedBox(height: 5.0),
                    Row(
                      mainAxisAlignment: MainAxisAlignment.spaceBetween,
                      children: <Widget>[
                        Text('Published on - ${NewsPostDetails.date as String}',
                            style:
                                TextStyle(fontSize: 14.0, color: Colors.grey)),
                      ],
                    ),
                    SizedBox(top: 40.0),
                    Textual content(NewsPostDetails.newsPostContent as String,
                        type: TextStyle(fontSize: 16.0)),
                    SizedBox(top: 110.0),
                  ]),
            ));
  }
}

Assist is extremely appreciated!