Question 74742 in Flutter Question posted in
The official Flutter documentation can be found here.

Flutter error : Null check operator used on a null value

I am trying to call an post Api in flutter to store data in MongoDb but I am getting an exception. This is the code.

  Future<void> postData() async {
    final url = Uri.parse('http://10.0.2.2:3000/data');

    final data = {
      'username': user!.displayName,
      'email': user!.email,
      'uid': user!.uid,
    };
    final jsonData = jsonEncode(data);

    final response = await http.post(url, body: jsonData, headers: {
      'Content-Type': 'application/json',
    });

    if (response.statusCode == 200) {
      print('Post request successful');
      print(response.body);
    } else {
      print('Error: ${response.statusCode}');
    }
  }

This is the error I am getting.

E/flutter ( 9199): [ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: Null check operator used on a null value
Tags:

2

Answers


  1. 0

    Try this :

        Future<void> postData() async {
        final url = Uri.parse('http://10.0.2.2:3000/data');
    
        if(user != null){
         final data = {
           'username': user!.displayName,
           'email': user!.email,
           'uid': user!.uid,
         };
        }
        else{
         final data = {
           'username': "",
           'email': "",
           'uid': "",
         };
        } 
        final jsonData = jsonEncode(data);
    
        final response = await http.post(url, body: jsonData, headers: {
          'Content-Type': 'application/json',
        });
    
        if (response.statusCode == 200) {
          print('Post request successful');
          print(response.body);
        } else {
          print('Error: ${response.statusCode}');
        }
      }
    Login or Signup to reply.
  2. 0

    User may be null.To fix the issues, you can try this.Since the user name , email ,uuid is string

    Future<void> postData() async {
    final url = Uri.parse('http://10.0.2.2:3000/data');

    final data = {
      'username': user?.displayName ?? "",
      'email': user?.email?? "",
      'uid': user?.uid ?? "",
    };
    final jsonData = jsonEncode(data);

    final response = await http.post(url, body: jsonData, headers: {
      'Content-Type': 'application/json',
    });

    if (response.statusCode == 200) {
      print('Post request successful');
      print(response.body);
    } else {
      print('Error: ${response.statusCode}');
    }
  }
    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search